The Functional Analysis Of The Unknow Gene Slr1122 In Synechocystis Sp. PCC 6803

Synechocystis sp. PCC 6803 is a useful model in the study of photosynthesis. The length of slr1122 is 753bp, which encodes a unknow protein with a length of 250 amino acid. Since the transcription direction of slr1122 is opposite to the genes around slr1122, the mutation would not result in the polar effect.We have got the A slr1122 by replacing slr1122 gene with Kanamycin gene. We focus on the physiology, metabolism, genetics and photosynthesis of A slr1122, in which the gene slr1122 was knocked out. Exploring the effects of the knockout of slr1122 may reveal the function of the unknown gene and also facilite to illustrate the involved regulatory mechanisms in cyanobacterial photosynthesis.The results show that:In⊿slr1122 lacking slr1122, the transcription of psaA, psaB and psbAI decreased remarkably, which may effect the course of photosynthesis and also bring about in the lower growth.⊿slr1122 needed more a series of essential ions in culture, e.g. the mutant grew worse on the shortage of N and P. The knockout of slr1122 made the mutant more sensitive to light, and in low light (LL)⊿slr1122 grew even better, while the mutant was less tolerant to high light (HL), which would bring about the lower growth. The loss of slr1122 could not disable the state transition. Compared with wild type, the content of phycobiliproteins and the chlorophyll a change significantly in the⊿slr1122 mutant, especially carotenoid. As a result, the color of WT was yellower than the⊿slr1122. Real-Time RT-PCR results showed that the expression of the five important enzymes in carotenoid synthsis had drecreased. It was also a reason that⊿slr1122 was more sensitive than WT when the BG11 was added MV. It is reported that slr1122 was found to interact with the hybrid sensory kinase sll1672, we had demonstrated that the protein of slr1122 and sll1672 can form complex, and be affected by ATP.