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Query: UMLS:C1832526 (PCC)
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The ndhC and ORF159 genes of the maize plastid DNA (ptDNA) were sequenced and maize ORF159 was used to screen a library of genomic DNA of the blue-green alga Synechocystis sp. PCC 6803. The cyanobacterial gene homologous to ORF159 (ORF157) was isolated and sequenced. In sequencing the region upstream of ORF157, reading frames with homology to the ndhC and psbG genes of maize ptDNA were identified. The ndhC and psbG genes overlap in the ptDNAs of maize, tobacco and Marchantia polymorpha, but are separated by a noncoding spacer in Synechocystis. Northern blot analysis showed that the ndhC, psbG and ORF157/159 genes are cotranscribed in maize and Synechocystis. The three genes occur in the same order in ptDNA of maize, tobacco, and M. polymorpha as in Synechocystis 6803. The amino acid sequences of the NDH-C, PSII-G and the ORF157/159 proteins deduced from the maize genes are 65%, 52% and 53% homologous to those of Synechocystis. However, the cyanobacterial and higher plant NDH-C protein sequences are only 23% homologous to the mitochondrial NDH-3 protein. Protein products of in vitro transcription/translation of the Synechocystis transcription unit had apparent molecular masses of 6 kDa (NDH-C), 25 kDa (PSII-G) and 22 kDa (ORF157) on lithium dodecyl sulfate (LDS) polyacrylamide gel electrophoresis. If these are components of an NADH dehydrogenase, cyanobacteria appear to resemble mitochondria more than they do Escherichia coli and Rhodopseudomonas capsulata with regard to this enzyme complex.
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PMID:Characterization of the ndhC-psbG-ORF157/159 operon of maize plastid DNA and of the cyanobacterium Synechocystis sp. PCC6803. 249 64

Band 7 proteins, which encompass members of the stomatin, prohibitin, flotillin, and HflK/C protein families, are integral membrane proteins that play important physiological roles in eukaryotes but are poorly characterized in bacteria. We have studied the band 7 proteins encoded by the cyanobacterium Synechocystis sp. strain PCC 6803, with emphasis on their structure and proposed role in the assembly and maintenance of the photosynthetic apparatus. Mutagenesis revealed that none of the five band 7 proteins (Slr1106, Slr1128, Slr1768, Sll0815, and Sll1021) was essential for growth under a range of conditions (including high light, salt, oxidative, and temperature stresses), although motility was compromised in an Slr1768 inactivation mutant. Accumulation of the major photosynthetic complexes in the thylakoid membrane and repair of the photosystem II complex following light damage were similar in the wild type and a quadruple mutant. Cellular fractionation experiments indicated that three of the band 7 proteins (Slr1106, Slr1768, and Slr1128) were associated with the cytoplasmic membrane, whereas Slr1106, a prohibitin homologue, was also found in the thylakoid membrane fraction. Blue native gel electrophoresis indicated that these three proteins, plus Sll0815, formed large (>669-kDa) independent complexes. Slr1128, a stomatin homologue, has a ring-like structure with an approximate diameter of 16 nm when visualized by negative stain electron microscopy. No evidence for band 7/FtsH supercomplexes was found. Overall, our results indicate that the band 7 proteins form large homo-oligomeric complexes but do not play a crucial role in the biogenesis of the photosynthetic apparatus in Synechocystis sp. strain PCC 6803.
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PMID:Structural and mutational analysis of band 7 proteins in the cyanobacterium Synechocystis sp. strain PCC 6803. 1968 40