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C B Michalowski

Publications and source records attributed to C B Michalowski.

24 records · Page 2Linked to original sources
PubMed1989

Evolutionary relationship of psbA genes from cyanobacteria, cyanelles and plastids.

The psbA gene is part of the reaction center of photosystem II in cyanobacteria and the plastids of higher plants. Its primary sequence is highly conserved among all species investigated so far and its sequence shows homologies with the L and M subunits of the reaction center of photosynthetic bacteria. We have analyzed the psbA homolog from a eukaryotic alga, Cyanophora paradoxa, where the gene is encoded on cyanelle DNA. These cyanelles are surrounded by a murein sacculus and resemble cyanobacteria in many other characteristics, although they are genuine organelles that functionally replace plastids. Analysis of the gene revealed a psbA protein identical in length (360 codons) with the cyanobacterial counterpart. The overall sequence identity is, however, more pronounced between cyanelle psbA and the shorter (353 amino acids) psbA product found in higher plants. These data strongly support the postulated bridge position of cyanelles between chloroplasts and free-living cyanobacteria.

Amino Acid Sequence↗
PubMed1989

Expression of the CAM-form of phospho(enol)pyruvate carboxylase and nucleotide sequence of a full length cDNA from Mesembryanthemum crystallinum.

We have determined the complete nucleotide sequence of a full length cDNA encoding the Crassulacean acid metabolism (CAM) isogene of phospho(enol)pyruvate carboxylase (PEPCase). The cDNA clone, 3348 bp in length, was obtained from mRNA isolated from Mesembryanthemum crystallinum (common ice plant) which had undergone salt stress and subsequent induction of CAM. The long open reading frame encodes PEPCase (EC 4.1.1.31) with a predicted molecular mass of 110533 daltons. The deduced amino acid sequence of the ice plant PEPCase is most similar to that from maize having an amino acid identity of 74.9%. Sequence identity in corresponding regions of the PEPCase proteins from Escherichia coli and the cyanobacterium Anacystis nidulans are 41.4% and 33.5%, respectively. A compilation of the four amino acid sequences permitted the identification of phylogenetically conserved regions within the proteins which may play a role in the function of this important enzyme in plant metabolism. Gene specific probes from 3' coding and noncoding regions of the cDNA clone used to probe genomic Southern blots established that this PEPCase gene is present in one copy in the nuclear genome of M. crystallinum. Transcripts arising from this gene increase dramatically when M. crystallinum is irrigated with 0.5 M NaCl, a stress which induces this plant to switch the primary fixation of CO2 from C3 (Calvin cycle) to CAM mode. The salt-induced mRNA encodes a PEPCase isoform which is undetectable in plants in the C3 mode as demonstrated by Northern hybridization.

Amino Acid Sequence↗
PubMed1989

Time Course of mRNA Induction Elicited by Salt Stress in the Common Ice Plant (Mesembryanthemum crystallinum).

In the facultative halophyte Mesembryanthemum crystallinum (common ice plant), irrigation with solutions containing NaCl induces an alternate mode of carbon dioxide fixation, Crassulacean acid metabolism (CAM). The salt stress protocol which we have established facilitates the study of CAM induction and the correlation of changes in metabolism and gene expression. We have studied the time course of mRNA induction for phosphoenolpyruvate carboxylase (PEPCase) (gene: ppc) and several other enzymes of carbon metabolism during stress. While CAM is not fully established for at least 10 days after the start of stress, mRNA amounts for PEPCase and for other CAM enzymes, such as Pyruvate orthophosphate dikinase, increase between day 2 and 3 after stress induction. Increases continue for at least 5 days. Concomitant with the increase of CAM transcripts, fluctuations in the mRNA amounts for genes rbcS and cab were observed. Transcript levels for these proteins decreased several-fold during a 3 to 4 day period.

Journal Article↗
PubMed1989

Expression during Salt Stress and Nucleotide Sequence of cDNA for Ferredoxin-NADP Reductase from Mesembryanthemum crystallinum.

In the facultative halophyte Mesembryanthemum crystallinum (common ice plant) the enzyme ferredoxin-NADP(+)-reductase (FNR) is coded for by a small family of 2 to 3 genes. We have determined the expression characteristics as the plants adapt to high salt and the nucleotide sequence of a full-length cDNA coding for the precursor of this chloroplast-located enzyme. On a developmental scale amounts of FNR transcripts and protein are highest in young emerging leaves. The FNR cDNA is a member of a class of genes whose expression is only slightly affected by salt stress. Even less pronounced than mRNA fluctuations, the amount of FNR protein is unaffected by salt stress. The longest FNR cDNA found was 1,419 nucleotides in size. It consisted of 74 nucleotides 5'-leader sequence, 1,095 nucleotides of protein coding sequence encoding 365 amino acids, and 247 nucleotides 3-region excluding a short poly(A(+)) tail. As expected for a nucleus-coded chloroplast protein an amino terminal transit peptide (52 amino acids in length) was found. The mature FNR protein is predicted to contain 313 amino acids corresponding to a protein of M(r) 35,713. The deduced amino acid sequence of the mature FNR protein is 93.2 and 85.9% identical to those of spinach and pea. The transit peptide of pea and spinach have 55.8 and 69.2% identity with that from ice plant.

Journal Article↗
PubMed1989

Salt stress leads to differential expression of two isogenes of phosphoenolpyruvate carboxylase during Crassulacean acid metabolism induction in the common ice plant.

The common ice plant is a facultative halophyte in which Crassulacean acid metabolism, a metabolic adaptation to arid environments, can be induced by irrigating plants with high levels of NaCl or by drought. This stress-induced metabolic transition is accompanied by up to a 50-fold increase in the activity of phosphoenolpyruvate carboxylase (PEPCase). To analyze the molecular basis of this plant response to water stress, we have isolated and characterized two members of the PEPCase gene family from the common ice plant. The PEPCase isogenes, designated Ppc1 and Ppc2, have conserved intron-exon organizations, are 76.4% identical at the nucleotide sequence level within exons, and encode predicted polypeptides with 83% amino acid identity. Steady-state levels of mRNAs from the two genes differ dramatically when plants are salt-stressed. Transcripts of Ppc1 increase about 30-fold in leaves within 5 days of salt stress. In contrast, steady-state levels of Ppc2 transcripts decrease slightly in leaf tissue over the same stress period. Steady-state levels of transcripts of both genes decrease in roots over 5 days of salt stress. We have used in vitro transcription assays with nuclei isolated from leaves to demonstrate that the increased expression of Ppc1 caused by water stress occurs in part at the transcriptional level.

Adaptation, Physiological↗