Function Analysis Of Slr0815in Synechocystis Sp. Strain PCC6803

Cyanobacteria represent a remarkable group among prokaryotic microorganismsbecause of their ability to perform oxygenic photosynthesis. It was well known thatfour photosynthetic membrane protein complexes locate in the thylakoid membrane,and they are photosytem I (PSI), photosytem II (PSII), Cytb6f and NDH-1.Thesephotosynthetic membrane protein complexes consist of linear electron transport andcyclic electron transport around PSI, essential for converting chemical energy toelectrical energy. Therefore, the photosynthetic electron flows mediated by thesetransports play an important physiological role in the cellular suvival, particularlyunder stress conditions, such as high light.Currently, how to identify new photosynthetic electron transport components orregulatory factors has become one of hot issues in the field of photosynthesis. In thisthesis, we obtained three high light-sensitive mutants by screening atransposon-tagged library of Synechocystis sp. strain PCC6803(hereafterSynechcoysitis6803). The reuslts showed that the mutants impaired the rate ofNDH-1-mediated CET (NDH-CET) and were tagged in the same slr0815gene thatencodes an unknown protein. To test whether mutation of slr0815is the result of thehigh light-sensitive phenotype, we constructed and obtained its complementary strain.The results of physiological activites confirmed that slr0815mutation resulting in thehigh light-sensitive phyenotype. Furthermore, Slr0815is found to be located in thethylakoid membranes, and its absence does not affect the PSI and PSII activity andthe NDH-1complex expression and assembly, but significantly impairs the rate oflinear electron transfer, and the abundance of cytf and ndhL genes. These resultsstrongly suggest that Slr0815participates in linear and cyclic electron transport. Therefore, this protein plays an extremely important physiological role inphotosynthetic electron transport in cyanobacteria.