Photosynthetic oxygen evolution is stabilized by cytochrome c550 against heat inactivation in Synechococcus sp. PCC 7002.
AUTOR(ES)
Nishiyama, Y
RESUMO
We investigated the factors responsible for the heat stability of photosynthetic oxygen evolution by examining thylakoid membranes from the cyanobacterium Synechococcus sp. PCC 7002. We found that treatment of the thylakoid membranes with 0.1% Triton X-100 resulted in a remarkable decrease in the heat stability of oxygen evolution, and that the heat stability could be restored by reconstituting the membranes with the components that had been extracted by Triton X-100. The protein responsible for the restoration of heat stability was purified from the Triton X-100 extract by two successive steps of chromatography. The purified protein had a molecular mass of 16 kD and exhibited the spectrophotometric properties of a c-type Cyt with a low redox potential. The dithionite-minus-ascorbate difference spectrum revealed an alpha band maximum at 551 nm. We were able to clone and sequence the gene encoding this Cyt from Synechococcus sp. PCC 7002, based on the partial amino-terminal amino acid sequence. The deduced amino acid sequence revealed a gene product consisting of a 34-residue transit peptide and a mature protein of 136 residues. The mature protein is homologous to Cyt c550, a Cyt with a low redox potential. Thus, our results indicate that Cyt c550 greatly affects the heat stability of oxygen evolution.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=159464Documentos Relacionados
- Physical genome map of the unicellular cyanobacterium Synechococcus sp. strain PCC 7002.
- PsaE Is Required for in Vivo Cyclic Electron Flow around Photosystem I in the Cyanobacterium Synechococcus sp. PCC 7002.
- Molecular cloning and characterization of the recA gene from the cyanobacterium Synechococcus sp. strain PCC 7002.
- Thermal protection of the oxygen-evolving machinery by PsbU, an extrinsic protein of photosystem II, in Synechococcus species PCC 7002.
- A Novel Nitrate/Nitrite Permease in the Marine Cyanobacterium Synechococcus sp. Strain PCC 7002