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At least 19 recordsLinked to original sources
PubMed1996

High degree of similarity between Chromatium vinosum and Chromatium minutissimum as revealed by riboprinting.

The riboprinting technique (restriction fragment length polymorphism [RFLP] analysis of PCR-amplified ribosomal DNA) was used to study five strains representing three species of the genus Chromatium. An RFLP analysis following digestion of the amplified small-subunit ribosomal DNA with 25 restriction enzymes revealed that the patterns obtained for all strains of Chromatium vinosum were identical. Chromatium gracile was different from C. vinosum with seven enzymes. On the other hand, Chromatium minutissimum produced the same patterns as C. vinosum with all enzymes, indicating that these organisms have a high degree of similarity. An RFLP analysis of the PCR-amplified spacer sequence between the 16S and 23S ribosomal DNAs gave similar results except that there was a larger number of differences between C. gracile and the other organisms examined.

Chromatium↗
PubMed1997

Chromatium glycolicum sp. nov., a moderately halophilic purple sulfur bacterium that uses glycolate as substrate

From the microbial mats that develop in Solar Lake, a new purple sulfur bacterium was isolated. This strain (Chromatium strain SL 3201) was morphologically similar to Chromatium gracile and Chromatium minutissimum. Chromatium SL 3201 was found to be a moderate halophile with a growth range between 2 and 20% NaCl (optimum 4-5% NaCl) and was able to grow photo-organotrophically using glycolate and glycerol. It is the first described phototrophic sulfur bacterium able to use glycolate. According to NaCl requirements and utilization of organic compounds, the strain is not related to any known species of the genus Chromatium. On the basis of its 16S rRNA gene sequence, it clusters with other Chromatium species and is most similar to Chromatium salexigens and Chr. gracile, but it is sufficiently separated to be considered as a new species of the genus. It is, therefore, described as Chromatium glycolicum sp. nov.

Journal Article↗
PubMed1991

Redox potentials of flavocytochromes c from the phototrophic bacteria, Chromatium vinosum and Chlorobium thiosulfatophilum.

The redox potentials of flavocytochromes c (FC) from Chromatium vinosum and Chlorobium thiosulfatophilum have been studied as a function of pH. Chlorobium FC has a single heme which has a redox potential of +98 mV at pH 7 (N = 1) that is independent of pH between 6 and 8. The average two-electron redox potential of the flavin extrapolated to pH 7 is +28 mV and decreases 35 mV/pH between pH 6 and 7. The anionic form of the flavin semiquinone is stabilized above pH 6. The redox potential of Chromatium FC is markedly lower than for Chlorobium. The two hemes in Chromatium FC appear to have a redox potential of 15 mV at pH 7 (N = 1), although they reside in very different structural environments. The hemes of Chromatium FC have a pH-dependent redox potential, which can be fit in the simplest case by a single ionization with pK = 7.05. The flavin in Chromatium FC has an average two-electron redox potential of -26 mV at pH 7 and decreases 30 mV/pH between pH 6 and 8. As with Chlorobium, the anionic form of the flavin semiquinone of Chromatium FC is stabilized above pH 6. The unusually high redox potential of the flavin, a stabilized anion radical, and sulfite binding to the flavin in both Chlorobium and Chromatium FCs are characteristics shared by the flavoprotein oxidases. By analogy with glycolate oxidase and lactate dehydrogenase for which there are three-dimensional structures, the properties of the FCs are likely to be due to a positively charged amino acid side chain in the vicinity of the N1 nitrogen of the flavin.

Bacteria↗
PubMed1985

Regulation of nitrogenase activity by covalent modification in Chromatium vinosum.

Nitrogenase in Chromatium vinosum was rapidly, but reversibly inhibited by NH4+. Activity of the Fe protein component of nitrogenase required both Mn2+ and activating enzyme. Activating enzyme from Rhodospirillum rubrum could replace Chromatium chromatophores in activating the Chromatium Fe protein, and conversely, a protein fraction prepared from Chromatium chromatophores was effective in activating R. rubrum Fe protein. Inactive Chromatium Fe protein contained a peptide covalently modified by a phosphate-containing molecule, which migrated the same in SDS-polyacrylamide gels as the modified subunit of R. rubrum Fe protein. In sum, these observations suggest that Chromatium nitrogenase activity is regulated by a covalent modification of the Fe protein in a manner similar to that of R. rubrum.

Ammonia↗
PubMed1984

Resonance Raman characterization of a novel, oxygen-binding heme protein from Chromatium vinosum.

Resonance Raman spectroscopy was employed to characterize the local heme environment of a high-spin, ligand-binding heme protein from Chromatium vinosum (Chromatium high-spin hemoprotein). High-frequency spectra obtained with both B- and Q-band excitation were found to resemble qualitatively those of deoxyhemoglobin (HbA). Differences between HbA and Chromatium high-spin hemoprotein spectra can be assigned to either the effects of a covalent linkage of the heme vinyls to the protein matrix or alterations in the heme-proximal ligand bonding interaction. Both kinematic and electronic effects were evident. The behavior of heme core-size sensitive modes and low-frequency modes in Chromatium high-spin hemoprotein may be an indication of distortions in the heme geometry of Chromatium high-spin hemoprotein relative to HbA. The effects of covalent bonding of the heme peripheral vinyls upon the vibrational, electronic, and geometric characteristics of the heme active site in Chromatium high-spin hemoprotein are discussed.

Chromatium↗
PubMed1975

Further studies on the subunit structure of Chromatium ribulose-1,5-phosphate carboxylase.

Upon alkali exposure Chromatium ribulose-1,5-bisphosphate carboxylase dissociates into constituent subunits, a catalytic oligomer of the larger subunit, A8, and monomeric form of the small subunit B. By sedimentation equilibrium molecular weights of the native enzyme and the catalytic oligomer produced by an alkali treatment were estimated to be 5.11 x 10 5 and 4.29 x 10 5, respectively. To provide information on reversibility of the dissociation by determining whether the enzymically inactive small subunit B of the whole enzyme molecule did indeed exchange with exogenously added subunit B a radioisotopic method was used. After initial alkaline dialysis at pH 9.2 of a mixture of a nonlabeled native enzyme preparation and 14C-labeled subunit B, and the subsequent dialysis at pH 7.0, incorporation of 14C into the recovered native enzyme was determined. Without the alkaline treatment there was no detectable exchange, while after alkaline dialysis for 5 and 10 hr the subunit B exchange was 89 and 82%, respectively. Rabbit antiserum prepared against the catalytic oligomer of the spinach ribulose-1,5-bisphosphate carboxylase, anti-(A) (spinach), inhibited the Chromatium carboxylase and oxygenase activities. This result together with the identical immunoprecipitation lines on an agar plate formed between the antiserum and the Chromatium carboxylase and between the antiserum and the catalytic subunit of the Chromatium enzyme strongly indicated structural near identity of the catalytic subunits of the spinach and Chromatium carboxylase molecules. Results also show that the catalytic site of the Chromatium ribulose-1,5-bisphosphate carboxylase and oxygenase exists in the large polypeptide chain.

Animals↗
PubMed1988

Transcriptional regulation of genes for plant-type ribulose-1,5-bisphosphate carboxylase/oxygenase in the photosynthetic bacterium, Chromatium vinosum.

The content of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the photosynthetic purple sulfur bacterium, Chromatium vinosum, grown either heterotrophically or autotrophically, was highly correlated with the level of 2.0-kb mRNA encoding genes for both large (rbcL) and small (rbcS) subunits. This result indicates the transcriptional regulation of Rubisco biosynthesis in Chromatium cells. In the analysis of transcripts for rbcL and rbcS in Escherichia coli transformed by a plasmid bearing both genes downstream of E. coli tac promoter (pCKS1), the mRNAs were found to be the same sizes as those from Chromatium. However, we were unable to detect mRNA for Rubisco in E. coli harboring a plasmid containing the genes for Rubisco and its own promoter without any E. coli promoters (pCUB1). In the in vitro transcription experiment of pCKS1 and pCUB1 by E. coli RNA polymerase, it was observed that the enzyme could not recognize the Rubisco promoter. Therefore, we have purified RNA polymerase from Chromatium cells and developed a homologous in vitro transcription system. We have detected factor(s) for transcriptional regulation from either heterotrophically or autotrophically grown cells of Chromatium using the homologous in vitro transcription system.

Chromatium↗
PubMed1984

Thioredoxin system of the photosynthetic anaerobe Chromatium vinosum.

Chromatium vinosum, an anaerobic photosynthetic purple sulfur bacterium, resembles aerobic bacterial cells in that it has an NADP-thioredoxin system composed of a single thioredoxin which is reduced by NADPH via NADP-thioredoxin reductase. Both protein components were purified to homogeneity, and some of their properties were determined. Chromatium vinosum thioredoxin was slightly larger than other bacterial thioredoxins (13 versus 12 kilodaltons) but was similar in its specificity (ability to activate chloroplast NADP-malate dehydrogenase more effectively than chloroplast fructose-1,6-bisphosphatase) and immunological properties. As in other bacteria, Chromatium vinosum NADP-thioredoxin reductase was an arsenite-sensitive flavoprotein composed of two 33.5-kilodalton subunits, that required thioredoxin for the NADPH-linked reduction of 5,5'-dithiobis(2-nitrobenzoic acid). Chromatium vinosum NADP-thioredoxin reductase very effectively reduced several different bacterial-type thioredoxins (Escherichia coli, Chlorobium thiosulfatophilum (this name has not been approved by the International Committee of Systematic Bacteriology), Rhizobium meliloti) but not others (Clostridium pasteurianum, spinach chloroplast thioredoxin m). The results show that Chromatium vinosum contains an NADP-thioredoxin system typical of evolutionarily more advanced microorganisms.

Anaerobiosis↗
PubMed1991

Covalent structure of the diheme cytochrome subunit and amino-terminal sequence of the flavoprotein subunit of flavocytochrome c from Chromatium vinosum.

The complete sequence of the 21-kDa cytochrome subunit of the flavocytochrome c (FC) from the purple phototrophic bacterium Chromatium vinosum has been determined to be as follows: EPTAEMLTNNCAGCHG THGNSVGPASPSIAQMDPMVFVEVMEGFKSGEIAS TIMGRIAKGYSTADFEKMAGYFKQQTYQPAKQSF DTALADTGAKLHDKYCEKCHVEGGKPLADEEDY HILAGQWTPYLQYAMSDFREERRPMEKKMASKL RELLKAEGDAGLDALFAFYASQQ. The sequence is the first example of a diheme cytochrome in a flavocytochrome complex. Although the locations of the heme binding sites and the heme ligands suggest that the cytochrome subunit is the result of gene doubling of a type I cytochrome c, as found with Azotobacter cytochrome c4, the extremely low similarity of only 7% between the two halves of the Chromatium FC heme subunit rather suggests that gene fusion is at the evolutionary origin of this cytochrome. The two halves also require a single residue internal deletion for alignment. The first half of the Chromatium FC heme subunit is 39% similar to the monoheme subunit of the FC from the green phototrophic bacterium Chlorobium thiosulfatophilum, but the second half is only 9% similar to the Chlorobium subunit. The N-terminal sequence of the Chromatium FC flavin subunit was determined up to residue 41 as AGRKVVVVGGGTGGATAAKYIKLADPSIEVTLIEP NTKYYT. It shows more similarity to the Chlorobium FC flavin subunit (60%) than do the two heme subunits. The N terminus of the flavin subunit is homologous to a number of flavoproteins, including succinate dehydrogenase, glutathione reductase, and monamine oxidase. There is no obvious homology to the Pseudomonas putida FC flavin subunit, which suggests that the two types of flavocytochrome c arose by convergent evolution. This is consistent with the dissimilar enzyme activities of FC as sulfide dehydrogenase in the phototrophic bacteria and as p-cresol methylhydroxylase in Pseudomonas. We also present a sequence "fingerprint" pattern for the recognition of FAD-binding proteins which is an extended version of the consensus sequence previously presented (Wierenga, R. K., Terpstra, P., and Hol, W. G. J. (1986) J. Mol. Biol. 187, 101-107) for nucleotide binding sites.

Amino Acid Sequence↗
PubMed1994

Characterization of flavocytochrome C552 from the thermophilic photosynthetic bacterium Chromatium tepidum.

A M(r) 68 kDa flavocytochrome c552 has been isolated from the thermophilic photosynthetic purple sulfur bacterium Chromatium tepidum and shown to consist of a M(r) 25 kDa subunit that contains two covalently bound heme c and a M(r) 43 kDa subunit that probably contains a single FAD. The prosthetic group content, absorbance spectra, and subunit composition of the C. tepidum flavocytochrome are quite similar to those previously reported for the flavocytochrome c552 isolated from a mesophilic Chromatium species, Chromatium vinosum. The oxidation-reduction properties of the hemes present in the C. tepidum flavocytochrome have been characterized by titrations, the effect of temperature on the catalytic activity of the protein has been investigated, and the heme environment has been characterized using resonance Raman spectroscopy.

Chromatium↗
PubMed1985

Expression of genes for subunits of plant-type RuBisCO from Chromatium and production of the enzymically active molecule in Escherichia coli.

A DNA fragment containing genes for both large (A) and small (B) subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) from a photosynthetic bacterium Chromatium vinosum was ligated with vectors for expressing unfused proteins and introduced into cells of Escherichia coli. The expressers of RuBisCO were screened on agar plates using the specific antibody raised against the native enzyme from Chromatium. The production of both subunits A and B in the expressers was demonstrated by an immunoblotting experiment. The amount of RuBisCO produced in the E. coli cells was as high as 15% of the total soluble protein after induction with isopropyl-beta-D-thiogalactoside. The specific activity of enzyme molecules produced in E. coli was nearly the same as that of the original Chromatium enzyme. On gel filtration high-performance liquid chromatography the two enzymes showed identical elution behavior, strongly indicating their similar quaternary structures.

Chromatium↗
PubMed1972

Observations on light-induced oxidation reactions in the electron transport system of Chromatium.

Light-induced cytochrome oxidations in Chromatium subchromatophore particles were studied in detail. These reactions were found to be dependent not only on redox potential, but also on the efficiency of coupling of the redox buffer electrons to the cytochrome system. Light-induced oxidation of the high potential cytochrome (c-556) was dependent on (a) the availability of reduced cytochrome and (b) the rate of light-induced oxidation (as determined by light intensity) vs. rate of cytochrome rereduction. Chromatium high potential iron-sulfur protein ("HiPISP") enhanced the rate of c-556 rereduction by mediating electron flow from artificial redox buffers to c-556. In these experiments, the light-induced oxidation of the low potential cytochrome (c-552.5) is dependent not only on the above parameters, but also on the rate of oxidation of the primary electron acceptor X. The interactions of purified Chromatium cytochromes with the light-induced cytochrome oxidation system are discussed.

Bacterial Proteins↗