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Query: UMLS:C1832526 (PCC)
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The genome of Synechocystis sp. PCC 6803 contains an operon with homology to the sulfate permease of other prokaryotes. We used antibodies raised against cytoplasmic membrane protein to find three genes with strong homology to sbpA, orf81 and cysT genes of the cyanobacterium Synechococcus sp. PCC 7942, Escherichia coli, Salmonella typhimurium and Marchantia polymorpha. It is likely that the permease genes are expressed and the proteins are inserted into the cytoplasmic membrane.
Plant Mol Biol 1993 Jan
PMID:Nucleotide sequence and homology comparison of two genes of the sulfate transport operon from the cyanobacterium Synechocystis sp. PCC 6803. 842 67

In eukaryotes, metallothioneins (MTs) are involved in cellular responses to elevated concentrations of certain metal ions. We report the isolation and analysis of a prokaryotic MT locus from Synechococcus PCC 7942. The MT locus (smt) includes smtA, which encodes a class II MT, and a divergently transcribed gene, smtB. The sites of transcription initiation of both genes have been mapped and features within the smt operator-promoter region identified. Elevated concentrations of the ionic species of Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn elicited an increase in the abundance of smtA transcripts. There was no detectable effect of elevated metal (Cd) on smtA transcript stability. Sequences upstream of smtA, fused to a promoterless lacZ gene, conferred metal-dependent beta-galactosidase activity in Synechococcus PCC 7942 (strain R2-PIM8). At maximum permissive concentrations, Zn was the most potent elicitor in vivo, followed by Cu and Cd with slight induction by Co and Ni. The deduced SmtB polypeptide has similarity to the ArsR and CadC proteins involved in resistance to arsenate/arsenite/antimonite and to Cd, contains a predicted helix-turn-helix DNA-binding motif and is shown to be a repressor of transcription from the smtA operator-promoter.
Mol Microbiol 1993 Jan
PMID:Isolation of a prokaryotic metallothionein locus and analysis of transcriptional control by trace metal ions. 844 25

Genomic rearrangements involving amplification of metallothionein (MT) genes have been reported in metal-tolerant eukaryotes. Similarly, we have recently observed amplification and rearrangement of a prokaryotic MT locus, smt, in cells of Synechococcus PCC 6301 selected for Cd tolerance. Following the characterization of this locus, the altered smt region has now been isolated from a Cd-tolerant cell line, C3.2, and its nucleotide sequence determined. This has identified a deletion within smtB, which encodes a trans-acting repressor of smt transcription. Two identical palindromic octanucleotides (5'-GCGATC-GC-3') traverse both borders of the excised element. This palindromic sequence is highly represented in the smt locus (7 occurrences in 1326 nucleotides) and analysis of the GenBank/EMBL/DDBJ DNA Nucleotide Sequence Data Libraries reveals that this is a highly iterated palindrome (HIP1) in other known sequences from Synechococcus strains (estimated to occur at an average frequency of once every c. 664 bp). HIP1 is also abundant in the genomes of other cyanobacteria. The functional significance of smtB deletion and the possible role of HIP1 in genome plasticity and adaptation in cyanobacteria are discussed.
Mol Microbiol 1993 Jan
PMID:Deletion within the metallothionein locus of cadmium-tolerant Synechococcus PCC 6301 involving a highly iterated palindrome (HIP1). 844 26

The phycobilisome rod linker genes in the two closely related cyanobacteria Synechococcus sp. PCC 6301 and Synechococcus sp. PCC 7942 were studied. Southern blot analysis showed that the genetic organization of the phycobilisome rod operon is very similar in the two strains. The phycocyanin gene pair is duplicated and separated by a region of about 2.5 kb. The intervening region between the duplicated phycocyanin gene pair was cloned from Synechococcus sp. PCC 6301 and sequenced. Analysis of this DNA sequence revealed the presence of three open reading frames corresponding to 273, 289 and 81 amino acids, respectively. Insertion of a kanamycin resistance cassette into these open reading frames indicated that they corresponded to the genes encoding the 30, 33 and 9 kDa rod linkers, respectively, as judged by the loss of specific linkers from the phycobilisomes of the insertional mutants. Amino acid compositions of the 30 and 33 kDa linkers derived from the DNA sequence were found to deviate from those of purified 33 and 30 kDa linkers in the amounts of glutamic acid/glutamine residues. On the basis of similarity of the amino acid sequence of the rod linkers between Synechococcus sp. PCC 6301 and Calothrix sp. PCC 7601 we name the genes encoding the 30, 33 and 9 kDa linkers cpcH, cpcI and cpcD, respectively. The three linker genes were found to be co-transcribed on an mRNA of 3700 nucleotides. However, we also detected a smaller species of mRNA, of 3400 nucleotides, which would encode only the cpcH and cpcI genes.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Gen Genet 1993 Feb
PMID:Cloning of the phycobilisome rod linker genes from the cyanobacterium Synechococcus sp. PCC 6301 and their inactivation in Synechococcus sp. PCC 7942. 845 71

The effect of iron on ferredoxin I specific mRNA levels was studied in the cyanobacterial strains Synechococcus sp. PCC 7942 (Anacystis nidulans R2) and Anabaena sp. PCC 7937 (Anabaena variabilis ATCC 29413). In both strains addition of iron to iron-limited cells resulted in a rapid increase in ferredoxin mRNA levels. To investigate the possible role of the ferredoxin promoter in iron regulation, a vector for promoter analysis in Synechococcus PCC 7942 strain R2-PIM9 was constructed, which contains the ferredoxin promoter fused to the gene encoding beta-glucuronidase (GUS) as reporter. Neither the Synechococcus nor the Anabaena ferredoxin promoter was able to direct iron-regulated GUS activity in Synechococcus R2-PIM9, indicating that transcription initiation is not responsible for the iron-dependent ferredoxin mRNA levels. Determination of the half-life of the ferredoxin transcript in iron-supplemented and iron-limited cells revealed that, in both strains, the ferredoxin transcript is much more stable in iron-supplemented cells than in iron-limited cells. These results lead to the conclusion that in these strains, iron-regulated expression of the ferredoxin I gene is mediated via differential mRNA stability.
Mol Microbiol 1993 Feb
PMID:Iron-dependent stability of the ferredoxin I transcripts from the cyanobacterial strains Synechococcus species PCC 7942 and Anabaena species PCC 7937. 845 69

Genes encoding the phycobilisome core subunits allophycocyanin alpha and beta and a small core linker protein in Synechocystis sp. strain PCC 6714 were cloned and sequenced. These genes form an operon, apcABC, with a single transcription start site and two possible termination sites, one following apcB and the other following apcC. The promoter region, like those of the apcABC operons of other cyanobacteria, does not resemble the consensus promoter sequences of Escherichia coli. However, the apcABC promoters identified in four strains of cyanobacteria have conserved sequences centered at -50 and -10 with respect to the start of transcription. The apcE gene, encoding the protein that links the phycobilisome core to the thylakoid membrane, was also cloned from Synechocystis 6714 and sequenced. It is unlinked to the apcABC operon. As in other Synechocystis strains, the LCM polypeptide encoded by the apcE gene contains three repeats of the basic phycobiliprotein linker domain. The apcE gene promoter sequence bears little resemblance to either the E. coli consensus or the apcABC promoter region, but it is similar to the corresponding regions of other cyanobacterial apcE genes. In these cases, there are conserved sequences centered at -40 and -10 with respect to the transcription start site. These conserved promoter elements from the apcABC and apcE genes were also identified in the corresponding 5'-flanking regions of eleven transcript starts for cpc genes encoding phycocyanin subunits in cyanobacteria and algal chloroplasts. These results suggest that a factor yet to be described participates in transcription of phycobiliprotein genes.
Plant Mol Biol 1993 Mar
PMID:Isolation and characterization of the genes encoding allophycocyanin subunits and two linker proteins from Synechocystis 6714. 846 79

The gene encoding nitrite reductase (nir) from the cyanobacterium Synechococcus sp. PCC 7942 has been identified and sequenced. This gene comprises 1536 nucleotides and would encode a polypeptide of 56,506 Da that shows similarity to nitrite reductase from higher plants and to the sulfite reductase hemoprotein from enteric bacteria. Identities found at positions corresponding to those amino acids which in the above-mentioned proteins hold the Fe4S4-siroheme active center suggest that nitrite reductase from Synechococcus bears an active site much alike that present in those reductases. The fact that the Synechococcus and higher-plant nitrite reductases are homologous proteins gives support to the endosymbiont theory for the origin of chloroplasts.
Plant Mol Biol 1993 Mar
PMID:Nitrite reductase gene from Synechococcus sp. PCC 7942: homology between cyanobacterial and higher-plant nitrite reductases. 849 Jan 40

In the context of other research cyanobacterial DNA sequences were obtained from genomic clones selected from libraries at random. Sequences from Synechococcus PCC 6301, Calothrix PCC 7601 and Calothrix D253 are now available from the GenBank/EMBL/DDBJ databases (accession number Z47089 to Z47128, Z47129 to Z47149 and Z47150 to Z47197, respectively) and have been searched for similarity to known sequences. Thirty-one putative new genes (encoding putative products with at least 40% identity over at least 50 amino acids, or the converse) are listed along with one sequence from Synechococcus PCC 6301 that had been isolated previously.
Plant Mol Biol 1995 Nov
PMID:Tabulation of thirty-one putative new genes from cyanobacteria. 853 57

PsbI is a small, integral membrane protein component of photosystem II (PSII), a pigment-protein complex in cyanobacteria, algae and higher plants. To understand the function of this protein, we have isolated the psbI gene from the unicellular cyanobacterium Synechocystis sp. PCC 6803 and determined its nucleotide sequence. Using an antibiotic-resistance cartridge to disrupt and replace the psbI gene, we have created mutants of Synechocystis 6803 that lack the PsbI protein. Analysis of these mutants revealed that absence of the PsbI protein results in a 25-30% loss of PSII activity. However, other PSII polypeptides are present in near wild-type amounts, indicating that no significant destabilization of the PSII complex has occurred. These results contrast with recently reported data indicating that PsbI-deficient mutants of the eukaryotic alga Chlamydomonas reinhardtii are highly light-sensitive and have a significantly lower (80-90%) titer of the PSII complex. In Synechocystis 6803, PsbI-deficient cells appear to be slightly more photosensitive than wild-type cells, suggesting that this protein, while not essential for PSII biogenesis or function, plays a role in the optimization of PSII activity.
Mol Gen Genet 1995 Dec 20
PMID:Directed inactivation of the psbI gene does not affect photosystem II in the cyanobacterium Synechocystis sp. PCC 6803. 854 27

Choline oxidase, isolated from the soil bacterium Arthrobacter globiformis, converts choline to glycinebetaine (N-trimethylglycine) without a requirement for any cofactors. The gene for this enzyme, designated codA, was cloned and introduced into the cyanobacterium Synechococcus sp. PCC 7942. The codA gene was expressed under the control of a strong constitutive promoter, and the transformed cells accumulated glycinebetaine at intracellular levels of 60-80 mM. Consequently the cells acquired tolerance to salt stress, as evaluated in terms of growth, accumulation of chlorophyll and photosynthetic activity.
Plant Mol Biol 1995 Dec
PMID:Transformation of Synechococcus with a gene for choline oxidase enhances tolerance to salt stress. 855 54


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