title: Thf1 interacts with PS I and stabilizes the PS I complex in Synechococcus sp. PCC7942.
abstract: Thylakoid formation1 protein (Thf1) is a multifunctional protein that is conserved in all photosynthetic organisms. In this study, we used the model cyanobacterium Synechococcus sp. PCC7942 (hereafter Synechococcus) to show that the level of Thf1 is altered in response to various stress conditions. Although this protein has been reported to be involved in thylakoid formation, the thylakoid membrane in the thf1 deletion strain (ΔThf1) was not affected. Compared with the WT, ΔThf1 showed reduced PS II activity, with increased levels of D1 under high light (HL) conditions, which was resulted from blocked D1 degradation by the FtsH protease and thus inhibits PS II repair. PS I was found to be more seriously affected than PS II in ΔThf1, even under low light conditions, suggesting that PS I damage could be the primary effect of thf1 deletion in Synechococcus. Further analysis revealed that the ΔThf1 mutant had a lower PS I subunit content and lower PS I stability under HL conditions. Further sucrose gradient fractionation of the membrane protein complexes and crosslinking and immunoblot analysis indicated that Thf1 interacts with PS I. Together, our results reveal that Thf1 interacts with PS I and thereby stabilizes PS I in Synechococcus.
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Zhan
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.|University of the Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.|University of the Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
authors.forename: Chenliu
authors.initials: C
authors.lastname: He
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D008027:Light; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D046940:Synechococcus / Q000378:metabolism*; D060431:Thylakoid Membrane Proteins / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D060431:Thylakoid Membrane Proteins