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Arthur R Grossman

Publications and source records attributed to Arthur R Grossman.

At least 19 recordsLinked to original sources
PubMed2006

A novel analytical method for in vivo phosphate tracking.

Genetically-encoded fluorescence resonance energy transfer (FRET) sensors for phosphate (P(i)) (FLIPPi) were engineered by fusing a predicted Synechococcus phosphate-binding protein (PiBP) to eCFP and Venus. Purified fluorescent indicator protein for inorganic phosphate (FLIPPi), in which the fluorophores are attached to the same PiBP lobe, shows P(i)-dependent increases in FRET efficiency. FLIPPi affinity mutants cover P(i) changes over eight orders of magnitude. COS-7 cells co-expressing a low-affinity FLIPPi and a Na(+)/P(i) co-transporter exhibited FRET changes when perfused with 100 microM P(i), demonstrating concentrative P(i) uptake by PiT2. FLIPPi sensors are suitable for real-time monitoring of P(i) metabolism in living cells, providing a new tool for fluxomics, analysis of pathophysiology or changes of P(i) during cell migration.

Animals↗
PubMed2006

The role of the STAS domain in the function and biogenesis of a sulfate transporter as probed by random mutagenesis.

Sulfate transporters in plants represent a family of proteins containing transmembrane domains that constitute the catalytic part of the protein and a short linking region that joins this catalytic moiety with a C-terminal STAS domain. The STAS domain resembles an anti-sigma factor antagonist of Bacillus subtilis, which is one distinguishing feature of the SLC26 transporter family; this family includes transporters for sulfate and other anions such as iodide and carbonate. Recent work has demonstrated that this domain is critical for the activity of Arabidopsis thaliana sulfate transporters, and specific lesions in this domain, or the exchange of STAS domains between different sulfate transporters, can severely impair transport activity. In this work we generated a Saccharomyces cerevisiae expression library of the A. thaliana Sultr1;2 gene with random mutations in the linking region-STAS domain and identified STAS domain lesions that altered Sultr1;2 biogenesis and/or function. A number of mutations in the beta-sheet that forms the core of the STAS domain prevented intracellular accumulation of Sultr1;2. In contrast, the linking region and one surface of the STAS domain containing N termini of the first and second alpha-helices have a number of amino acids critical for the function of the protein; mutations in these regions still allow protein accumulation in the plasma membrane, but the protein is no longer capable of efficiently transporting sulfate into cells. These results suggest that the STAS domain is critical for both the activity and biosynthesis/stability of the transporter, and that STAS sub-domains correlate with these specific functions.

Alleles↗
PubMed2006

In situ analysis of nitrogen fixation and metabolic switching in unicellular thermophilic cyanobacteria inhabiting hot spring microbial mats.

Genome sequences of two Synechococcus ecotypes inhabiting the Octopus Spring microbial mat in Yellowstone National Park revealed the presence of all genes required for nitrogenase biosynthesis. We demonstrate that nif genes of the Synechococcus ecotypes are expressed in situ in a region of the mat that varies in temperature from 53.5 degrees C to 63.4 degrees C (average 60 degrees C); transcripts are only detected at the end of the day when the mat becomes anoxic. Nitrogenase activity in mat samples was also detected in the evening. Hitherto, N2 fixation in hot spring mats was attributed either to filamentous cyanobacteria (not present at >50 degrees C in these mats) or to heterotrophic bacteria. To explore how energy-generating processes of the Synechococcus ecotypes track natural light and O2 conditions, we evaluated accumulation of transcripts encoding proteins involved in photosynthesis, respiration, and fermentation. Transcripts from photosynthesis (cpcF, cpcE, psaB, and psbB) and respiration (coxA and cydA) genes declined in the evening. In contrast, transcripts encoding enzymes that may participate in fermentation fell into two categories; some (ldh, pdhB, ald, and ackA) decreased in the evening, whereas others (pflB, pflA, adhE, and acs) increased at the end of the day and remained high into the night. Energy required for N2 fixation during the night may be derived from fermentation pathways that become prominent as the mat becomes anoxic. In a broader context, our data suggest that there are critical regulatory switches in situ that are linked to the diel cycle and that these switches alter many metabolic processes within the microbial mat.

Energy Metabolism↗
PubMed2006

Phototropin involvement in the expression of genes encoding chlorophyll and carotenoid biosynthesis enzymes and LHC apoproteins in Chlamydomonas reinhardtii.

Phototropin (PHOT) is a photoreceptor involved in a variety of blue-light-elicited physiological processes including phototropism, chloroplast movement and stomatal opening in plants. The work presented here tests whether PHOT is involved in expression of light-regulated genes in Chlamydomonas reinhardtii. When C. reinhardtii was transferred from the dark to very low-fluence rate white light, there was a substantial increase in the level of transcripts encoding glutamate-1-semialdehyde aminotransferase (GSAT), phytoene desaturase (PDS) and light-harvesting polypeptides (e.g. LHCBM6). Increased levels of these transcripts were also elicited by low-intensity blue light, and this blue-light stimulation was suppressed in three different RNAi strains that synthesize low levels of PHOT. The levels of GSAT and LHCBM6 transcripts also increased following exposure of algal cells to low-intensity red light (RL). The red-light-dependent increase in transcript abundance was not affected by the electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea, implying that the influence of RL on transcript accumulation was not controlled by cytoplasmic redox conditions, and that a red-light photoreceptor(s) may be involved in regulating the levels of transcripts from specific photosynthesis-related genes in C. reinhardtii. Interestingly, elevated GSAT and LHCBM6 transcript levels in RL were significantly reduced in the PHOT RNAi strains, which raises the possibility of co-action between blue and RL signaling pathways. Microarray experiments indicated that the levels of several transcripts for photosystem (PS) I and II polypeptides were also modulated by PHOT. These data suggest that, in C. reinhardtii, (i) PHOT is involved in blue-light-mediated changes in transcript accumulation, (ii) synchronization of the synthesis of chlorophylls (Chl), carotenoids, Chl-binding proteins and other components of the photosynthetic apparatus is achieved, at least in part, through PHOT-mediated signaling, and (iii) a red-light photoreceptor can also influence levels of certain transcripts associated with photosynthetic function, although its action requires normal levels of PHOT.

Algal Proteins↗
PubMed2006

Genome-based approaches to understanding phosphorus deprivation responses and PSR1 control in Chlamydomonas reinhardtii.

The Chlamydomonas reinhardtii transcription factor PSR1 is required for the control of activities involved in scavenging phosphate from the environment during periods of phosphorus limitation. Increased scavenging activity reflects the development of high-affinity phosphate transport and the expression of extracellular phosphatases that can cleave phosphate from organic compounds in the environment. A comparison of gene expression patterns using microarray analyses and quantitative PCRs with wild-type and psr1 mutant cells deprived of phosphorus has revealed that PSR1 also controls genes encoding proteins with potential "electron valve" functions--these proteins can serve as alternative electron acceptors that help prevent photodamage caused by overexcitation of the photosynthetic electron transport system. In accordance with this finding, phosphorus-starved psr1 mutants die when subjected to elevated light intensities; at these intensities, the wild-type cells still exhibit rapid growth. Acclimation to phosphorus deprivation also involves a reduction in the levels of transcripts encoding proteins involved in photosynthesis and both cytoplasmic and chloroplast translation as well as an increase in the levels of transcripts encoding stress-associated chaperones and proteases. Surprisingly, phosphorus-deficient psr1 cells (but not wild-type cells) also display expression patterns associated with specific responses to sulfur deprivation, suggesting a hitherto unsuspected link between the signal transduction pathways involved in controlling phosphorus and sulfur starvation responses. Together, these results demonstrate that PSR1 is critical for the survival of cells under conditions of suboptimal phosphorus availability and that it plays a key role in controlling both scavenging responses and the ability of the cell to manage excess absorbed excitation energy.

Algal Proteins↗
PubMed2005

Generation of an oligonucleotide array for analysis of gene expression in Chlamydomonas reinhardtii.

The availability of genome sequences makes it possible to develop microarrays that can be used for profiling gene expression over developmental time, as organisms respond to environmental challenges, and for comparison between wild-type and mutant strains under various conditions. The desired characteristics of microarrays (intense signals, hybridization specificity and extensive coverage of the transcriptome) were not fully met by the previous Chlamydomonas reinhardtii microarray: probes derived from cDNA sequences (approximately 300 bp) were prone to some nonspecific cross-hybridization and coverage of the transcriptome was only approximately 20%. The near completion of the C. reinhardtii nuclear genome sequence and the availability of extensive cDNA information have made it feasible to improve upon these aspects. After developing a protocol for selecting a high-quality unigene set representing all known expressed sequences, oligonucleotides were designed and a microarray with approximately 10,000 unique array elements (approximately 70 bp) covering 87% of the known transcriptome was developed. This microarray will enable researchers to generate a global view of gene expression in C. reinhardtii. Furthermore, the detailed description of the protocol for selecting a unigene set and the design of oligonucleotides may be of interest for laboratories interested in developing microarrays for organisms whose genome sequences are not yet completed (but are nearing completion).

Animals↗
PubMed2005

Insights into the acclimation of Chlamydomonas reinhardtii to sulfur deprivation.

During sulfur deprivation, the photosynthetic green alga Chlamydomonas reinhardtii develops a high-affinity sulfate uptake system and increases the expression of genes encoding proteins involved in sulfur assimilation. Although two regulatory elements, SAC1 and SAC3, have been shown to be required for normal acclimation of C. reinhardtii to sulfur deprivation, a number of other regulatory elements appear to also be involved. The molecular mechanisms by which these regulatory elements function are largely unknown. This manuscript presents our current knowledge of sulfur deprivation responses and the regulation of these responses in C. reinhardtii. In addition, we present preliminary results of a sub-saturation screen for novel sulfur acclimation mutants of C. reinhardtii. A speculative model, incorporating the activities of established regulatory elements with putative novel components of the signal transduction pathway(s) is discussed.

Acclimatization↗
PubMed2005

Genome-based examination of chlorophyll and carotenoid biosynthesis in Chlamydomonas reinhardtii.

The unicellular green alga Chlamydomonas reinhardtii is a particularly important model organism for the study of photosynthesis since this alga can grow heterotrophically, and mutants in photosynthesis are therefore conditional rather than lethal. The recently developed tools for genomic analyses of this organism have allowed us to identify most of the genes required for chlorophyll and carotenoid biosynthesis and to examine their phylogenetic relationships with homologous genes from vascular plants, other algae, and cyanobacteria. Comparative genome analyses revealed some intriguing features associated with pigment biosynthesis in C. reinhardtii; in some cases, there are additional conserved domains in the algal and plant but not the cyanobacterial proteins that may directly influence their activity, assembly, or regulation. For some steps in the chlorophyll biosynthetic pathway, we found multiple gene copies encoding putative isozymes. Phylogenetic studies, theoretical evaluation of gene expression through analysis of expressed sequence tag data and codon bias of each gene, enabled us to generate hypotheses concerning the function and regulation of the individual genes, and to propose targets for future research. We have also used quantitative polymerase chain reaction to examine the effect of low fluence light on the level of mRNA accumulation encoding key proteins of the biosynthetic pathways and examined differential expression of those genes encoding isozymes that function in the pathways. This work is directing us toward the exploration of the role of specific photoreceptors in the biosynthesis of pigments and the coordination of pigment biosynthesis with the synthesis of proteins of the photosynthetic apparatus.

Amino Acid Sequence↗
PubMed2005

The LPB1 gene is important for acclimation of Chlamydomonas reinhardtii to phosphorus and sulfur deprivation.

Organisms exhibit a diverse set of responses when exposed to low-phosphate conditions. Some of these responses are specific for phosphorus limitation, including responses that enable cells to efficiently scavenge phosphate from internal and external stores via the production of high-affinity phosphate transporters and the synthesis of intracellular and extracellular phosphatases. Other responses are general and occur under a number of different environmental stresses, helping coordinate cellular metabolism and cell division with the growth potential of the cell. In this article, we describe the isolation and characterization of a mutant of Chlamydomonas reinhardtii, low-phosphate bleaching (lpb1), which dies more rapidly than wild-type cells during phosphorus limitation. The responses of this mutant to nitrogen limitation appear normal, although the strain is also somewhat more sensitive than wild-type cells to sulfur deprivation. Interestingly, depriving the cells of both nutrients simultaneously allows for sustained survival that is similar to that observed with wild-type cells. Furthermore, upon phosphorus deprivation, the lpb1 mutant, like wild-type cells, exhibits increased levels of mRNA encoding the PHOX alkaline phosphatase, the PTB2 phosphate transporter, and the regulatory element PSR1. The mutant strain is also able to synthesize the extracellular alkaline phosphatase activity upon phosphorus deprivation and the arylsulfatase upon sulfur deprivation, suggesting that the specific responses to phosphorus and sulfur deprivation are normal. The LPB1 gene was tagged by insertion of the ARG7 gene, which facilitated its isolation and characterization. This gene encodes a protein with strong similarity to expressed proteins in Arabidopsis (Arabidopsis thaliana) and predicted proteins in Oryza sativa and Parachlamydia. A domain in the protein contains some similarity to the superfamily of nucleotide-diphospho-sugar transferases, and it is likely to be localized to the chloroplast or mitochondrion based on programs that predict subcellular localization. While the precise catalytic role and physiological function of the putative protein is not known, it may function in some aspect of polysaccharide metabolism and/or influence phosphorus metabolism (either structural or regulatory) in a way that is critical for allowing the cells to acclimate to nutrient limitation conditions.

Acclimatization↗
PubMed2004

Probing the function of STAS domains of the Arabidopsis sulfate transporters.

Sulfate transporters in plants and animals are structurally conserved and have an amino-terminal domain that functions in transport and a carboxyl-terminal region that has been designated the STAS domain. The STAS domain in sulfate transporters has significant similarity to bacterial anti-sigma factor antagonists. To determine if the STAS domain has a role in controlling the activity of sulfate transporters, their stability, or their localization to the plasma membrane, we examined the effect of deleting or modifying the STAS domain of dominant sulfate transporters in roots of Arabidopsis thaliana. The A. thaliana Sultr1;2 and Sultr1;1 sulfate transporters rescue the methionine-dependent growth phenotype of the yeast sulfate transporter mutant strain CP154-7B. Constructs of Sultr1;2 in which the STAS domain was deleted (DeltaSTAS) resulted in synthesis of a truncated polypeptide that was unable to rescue the CP154-7B phenotype. The inability of these constructs to rescue the mutant phenotype probably reflected both low level cellular accumulation of the transporter and the inability of the truncated protein to localize to the plasma membrane. Fusing the STAS domain from other sulfate transporters to Sultr1;2 DeltaSTAS constructs restored elevated accumulation and plasma membrane localization, although the kinetics of sulfate uptake in the transformants were markedly altered with respect to transformants synthesizing wild-type Sultr1;2 protein. These results suggest that the STAS domain is essential, either directly or indirectly, for facilitating localization of the transporters to the plasma membrane, but it also appears to influence the kinetic properties of the catalytic domain of transporters.

Amino Acid Sequence↗
PubMed2004

RcaE is a complementary chromatic adaptation photoreceptor required for green and red light responsiveness.

The recent discovery of large numbers of phytochrome photoreceptor genes in both photosynthetic and non-photosynthetic prokaryotes has led to efforts to understand their physiological roles in environmental acclimation. One receptor in this class, RcaE, is involved in controlling complementary chromatic adaptation, a process that regulates the transcription of operons encoding light-harvesting proteins in cyanobacteria. Although all previously identified phytochrome responses are maximally sensitive to red and far red light, complementary chromatic adaptation is unique in that it is responsive to green and red light. Here, we present biochemical and genetic evidence demonstrating that RcaE is a photoreceptor and that it requires the cysteine at position 198 to ligate an open chain tetrapyrrole covalently in a manner analogous to chromophore attachment in plant phytochromes. Furthermore, although the wild-type rcaE gene can rescue red and green light photoresponses of an rcaE null mutant, a gene in which the codon for cysteine 198 is converted to an alanine codon rescues the red light but not the green light response. Thus, RcaE is a photoreceptor that is required for both green and red light responsiveness during complementary chromatic adaptation and is the first identified phytochrome class sensor that is involved in sensing and responding to green and red light rather than red and far red light.

Bacterial Proteins↗
PubMed2004

Insights into the survival of Chlamydomonas reinhardtii during sulfur starvation based on microarray analysis of gene expression.

Responses of photosynthetic organisms to sulfur starvation include (i) increasing the capacity of the cell for transporting and/or assimilating exogenous sulfate, (ii) restructuring cellular features to conserve sulfur resources, and (iii) modulating metabolic processes and rates of cell growth and division. We used microarray analyses to obtain a genome-level view of changes in mRNA abundances in the green alga Chlamydomonas reinhardtii during sulfur starvation. The work confirms and extends upon previous findings showing that sulfur deprivation elicits changes in levels of transcripts for proteins that help scavenge sulfate and economize on the use of sulfur resources. Changes in levels of transcripts encoding members of the light-harvesting polypeptide family, such as LhcSR2, suggest restructuring of the photosynthetic apparatus during sulfur deprivation. There are also significant changes in levels of transcripts encoding enzymes involved in metabolic processes (e.g., carbon metabolism), intracellular proteolysis, and the amelioration of oxidative damage; a marked and sustained increase in mRNAs for a putative vanadium chloroperoxidase and a peroxiredoxin may help prolong survival of C. reinhardtii during sulfur deprivation. Furthermore, many of the sulfur stress-regulated transcripts (encoding polypeptides associated with sulfate uptake and assimilation, oxidative stress, and photosynthetic function) are not properly regulated in the sac1 mutant of C. reinhardtii, a strain that dies much more rapidly than parental cells during sulfur deprivation. Interestingly, sulfur stress elicits dramatic changes in levels of transcripts encoding putative chloroplast-localized chaperones in the sac1 mutant but not in the parental strain. These results suggest various strategies used by photosynthetic organisms during acclimation to nutrient-limited growth.

Animals↗
PubMed2004

Control of photosynthetic and high-light-responsive genes by the histidine kinase DspA: negative and positive regulation and interactions between signal transduction pathways.

We have deleted a gene for a sensor histidine kinase, dspA (or hik33), in the cyanobacterium Synechocystis sp. strain PCC6803. In low and moderate light, the mutant grew slowly under photoautotrophic conditions, with a doubling time of approximately 40 h, and had severely reduced photosynthetic oxygen evolution. When the mutant was maintained in low or moderate light in the presence of glucose, its growth rate was only somewhat lower than that of wild-type cells. However, the mutant was light sensitive and rapidly died in high light. Furthermore, levels of many transcripts encoding genes associated with photosynthesis were altered in the mutant relative to wild-type Synechocystis sp. strain PCC6803 both in low light and following exposure to high light. There was constitutive expression of several high-light-inducible genes, including hli, psbAIII, and gpx2; there was little increased accumulation of sodB mRNA in high light; and the cells failed to accumulate cpcBA and psaAB mRNAs in low light in the presence of glucose, although a normal decline in the levels of these mRNAs was observed during exposure to high light. These results suggest that DspA is involved in controlling sets of photosynthetic and high-light-responsive genes, either directly or indirectly. These and other results, some of which are presented in a companion paper (C.-J. Tu, J. Shrager, R. Burnap, B. L. Postier, and A. R. Grossman, J. Bacteriol. 186:3889-3902, 2004), suggest that DspA acts as a global regulator that helps coordinate cellular metabolism with growth limitations imposed by environmental conditions.

Bacterial Proteins↗
PubMed2004

Consequences of a deletion in dspA on transcript accumulation in Synechocystis sp. strain PCC6803.

A sensor histidine kinase of Synechococcus sp. strain PCC7942, designated nblS, was previously identified and shown to be critical for the acclimation of cells to high-light and nutrient limitation conditions and to influence the expression of a number of light-responsive genes. The nblS orthologue in Synechocystis sp. strain PCC6803 is designated dspA (also called hik33). We have generated a dspA null mutant and analyzed global gene expression in both the mutant and wild-type strains under high- and low-light conditions. The mutant is aberrant for the expression of many genes encoding proteins critical for photosynthesis, phosphate and carbon acquisition, and the amelioration of stress conditions. Furthermore, transcripts from a number of genes normally detected only during exposure of wild-type cells to high-light conditions become partially constitutive in the low-light-grown dspA mutant. Other genes for which transcripts decline upon exposure of wild-type cells to high light are already lower in the mutant during growth in low light. These results suggest that DspA may influence gene expression in both a positive and a negative manner and that the dspA mutant behaves as if it were experiencing stress conditions (e.g., high-light exposure) even when maintained at near-optimal growth conditions for wild-type cells. This is discussed with respect to the importance of DspA for regulating the responses of the cell to environmental cues.

Bacterial Proteins↗
PubMed2004

AplA, a member of a new class of phycobiliproteins lacking a traditional role in photosynthetic light harvesting.

All known phycobiliproteins have light-harvesting roles during photosynthesis and are found in water-soluble phycobilisomes, the light-harvesting complexes of cyanobacteria, cyanelles, and red algae. Phycobiliproteins are chromophore-bearing proteins that exist as heterodimers of alpha and beta subunits, possess a number of highly conserved amino acid residues important for dimerization and chromophore binding, and are invariably 160 to 180 amino acids long. A new and unusual group of proteins that is most closely related to the allophycocyanin members of the phycobiliprotein superfamily has been identified. Each of these proteins, which have been named allophycocyanin-like (Apl) proteins, apparently contains a 28-amino-acid extension at its amino terminus relative to allophycocyanins. Apl family members possess the residues critical for chromophore interactions, but substitutions are present at positions implicated in maintaining the proper alpha-beta subunit interactions and tertiary structure of phycobiliproteins, suggesting that Apl proteins are able to bind chromophores but fail to adopt typical allophycocyanin conformations. AplA isolated from the cyanobacterium Fremyella diplosiphon contained a covalently attached chromophore and, although present in the cell under a number of conditions, was not detected in phycobilisomes. Thus, Apl proteins are a new class of photoreceptors with a different cellular location and structure than any previously described members of the phycobiliprotein superfamily.

Amino Acid Sequence↗
PubMed2004

Chlamydomonas reinhardtii in the landscape of pigments.

This review focuses on the biosynthesis of pigments in the unicellular alga Chlamydomonas reinhardtii and their physiological and regulatory functions in the context of information gathered from studies of other photosynthetic organisms. C. reinhardtii is serving as an important model organism for studies of photosynthesis and the pigments associated with the photosynthetic apparatus. Despite extensive information pertaining to the biosynthetic pathways critical for making chlorophylls and carotenoids, we are just beginning to understand the control of these pathways, the coordination between pigment and apoprotein synthesis, and the interactions between the activities of these pathways and those for other important cellular metabolites branching from these pathways. Other exciting areas relating to pigment function are also emerging: the role of intermediates of pigment biosynthesis as messengers that coordinate metabolism in the chloroplast with nuclear gene activity, and the identification of photoreceptors and their participation in critical cellular processes including phototaxis, gametogenesis, and the biogenesis of the photosynthetic machinery. These areas of research have become especially attractive for intensive development with the application of potent molecular and genomic tools currently being applied to studies of C. reinhardtii.

Animals↗
PubMed2003

Elimination of high-light-inducible polypeptides related to eukaryotic chlorophyll a/b-binding proteins results in aberrant photoacclimation in Synechocystis PCC6803.

The hli genes, present in cyanobacteria, algae and vascular plants, encode small proteins [high-light-inducible polypeptides (HLIPs)] with a single membrane-spanning alpha-helix related to the first and third helices of eukaryotic chlorophyll a/b-binding proteins. The HLIPs are present in low amounts in low light and they accumulate transiently at high light intensities. We are investigating the function of those polypeptides in a Synechocystis PCC6803 mutant lacking four of the five hli genes. Growth of the quadruple hli mutant was adversely affected by high light intensities. The most striking effect of the quadruple hli mutation was an alteration of cell pigmentation. Pigment changes associated with cell acclimation to increasing light intensity [i.e. decrease in light-harvesting pigments, accumulation of the carotenoid myxoxanthophyll and decrease in photosystem I (PSI)-associated chlorophylls] were strongly exacerbated in the quadruple hli mutant, resulting in yellowish cultures that bleached in high light and died as light intensities exceeded (>500 micromol photon m(-2) s(-1)). However, these pigment changes were not associated with an inhibition of photosynthesis, as probed by in vivo chlorophyll fluorescence, photoacoustic and O(2)-evolution measurements. On the contrary, the HLIP deficiency was accompanied by a stimulation of the photochemical activity, especially in high-light-grown cells. Western blot analyses revealed that the PSI reaction center level (PsaA/B) was noticeably reduced in the quadruple hli mutant relative to the wild type, whereas the abundance of the PSII reaction center protein D1 was comparatively little affected. The hli mutations did not enhance photoinhibition and photooxidation when cells were exposed over a short term to a very high light intensity. Together, the results of this study indicate that HLIPs are critical in the adaptation of the cyanobacterium to variations in light intensity. The data are consistent with the idea that HLIPs are involved, through a direct or indirect means, in nonphotochemical dissipation of absorbed light energy.

Acclimatization↗