title: Different B-type methionine sulfoxide reductases in Chlamydomonas may protect the alga against high-light, sulfur-depletion, or oxidative stress.
abstract: The genome of unicellular green alga Chlamydomonas reinhardtii contains four genes encoding B-type methionine sulfoxide reductases, MSRB1.1, MSRB1.2, MSRB2.1, and MSRB2.2, with functions largely unknown. To understand the cell defense system mediated by the methionine sulfoxide reductases in Chlamydomonas, we analyzed expression and physiological roles of the MSRBs under different abiotic stress conditions using immunoblotting and quantitative polymerase chain reaction (PCR) analyses. We showed that the MSRB2.2 protein was accumulated in cells treated with high light (1,300 µE/m² per s), whereas MSRB1.1 was accumulated in the cells under 1 mmol/L H₂O₂ treatment or sulfur depletion. We observed that the cells with the MSRB2.2 knockdown and overexpression displayed increased and decreased sensitivity to high light, respectively, based on in situ chlorophyll a fluorescence measures. We also observed that the cells with the MSRB1.1 knockdown and overexpression displayed decreased and increased tolerance to sulfur-depletion and oxidative stresses, respectively, based on growth and H₂-producing performance. The physiological implications revealed from the experimental data highlight the importance of MSRB2.2 and MSRB1.1 in protecting Chlamydomonas cells against adverse conditions such as high-light, sulfur-depletion, and oxidative stresses.
authors.affiliation: Key Laboratory of Photobiology, Institute of Botany, the Chinese Academy of Sciences, Beijing, 100093, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.forename: Mei
authors.initials: M
authors.lastname: Chen
authors.forename: Dongmei
authors.initials: D
authors.lastname: Cheng
authors.forename: Haomeng
authors.initials: H
authors.lastname: Yang
authors.forename: Yongle
authors.initials: Y
authors.lastname: Sun
authors.forename: Heyi
authors.initials: H
authors.lastname: Zhou
authors.forename: Fang
authors.initials: F
authors.lastname: Huang
mesh_terms: D000917:Antibody Formation; D002696:Chlamydomonas / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008027:Light; D051150:Methionine Sulfoxide Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects*; D010641:Phenotype; D030821:Plants, Genetically Modified; D020539:Sequence Analysis, Protein; D013312:Stress, Physiological / Q000528:radiation effects; D013455:Sulfur / Q000172:deficiency*
chemical_list: D013455:Sulfur; D006861:Hydrogen Peroxide; D051150:Methionine Sulfoxide Reductases
keywords: Chlamydomonas; MSRB; high light; oxidative stress; sulfur deprivation