title: Subunit Q Is Required to Stabilize the Large Complex of NADPH Dehydrogenase in Synechocystis sp. Strain PCC 6803.
abstract: Two major complexes of NADPH dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1, NdhF1, and NdhP, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, NDH-1-dependent cyclic electron transport around photosystem I, and CO2 uptake. Two mutants sensitive to high light for growth and impaired in cyclic electron transport around photosystem I were isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in an open reading frame encoding a product highly homologous to NdhQ, a single-transmembrane small subunit of the NDH-1L complex, identified in Thermosynechococcus elongatus by proteomics strategy. Deletion of ndhQ disassembled about one-half of the NDH-1L to NDH-1M and consequently impaired respiration, but not CO2 uptake. During prolonged incubation of the thylakoid membrane with n-dodecyl-β-D-maltoside at room temperature, the rest of the NDH-1L in ΔndhQ was disassembled completely to NDH-1M and was much faster than in the wild type. In the ndhP-deletion mutant (ΔndhP) background, absence of NdhQ almost completely disassembled the NDH-1L to NDH-1M, similar to the results observed in the ΔndhD1/ΔndhD2 mutant. We therefore conclude that both NdhQ and NdhP are essential to stabilize the NDH-1L complex.
authors: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China (J.Z., W.R., F.G., W.M.); andBioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan (T.O.).
authors: Jiaohong
authors: J
authors: Zhao
authors: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China (J.Z., W.R., F.G., W.M.); andBioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan (T.O.).
authors: Weiqiong
authors: W
authors: Rong
authors: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China (J.Z., W.R., F.G., W.M.); andBioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan (T.O.).
authors: Fudan
authors: http://orcid.org/0000-0002-8882-5968
authors: F
authors: Gao
authors: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China (J.Z., W.R., F.G., W.M.); andBioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan (T.O.).
authors: Teruo
authors: http://orcid.org/0000-0001-6061-8273
authors: T
authors: Ogawa
authors: College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China (J.Z., W.R., F.G., W.M.); andBioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan (T.O.) wma@shnu.edu.cn.
authors: Weimin
authors: http://orcid.org/0000-0003-4964-415X
authors: W
authors: Ma
mesh_terms: D015153:Blotting, Western; D019069:Cell Respiration / Q000528:radiation effects; D004579:Electron Transport / Q000528:radiation effects; D004795:Enzyme Stability / Q000528:radiation effects; D017353:Gene Deletion; D052836:Heterotrophic Processes / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009252:NADPH Dehydrogenase / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D046939:Synechocystis / Q000201:enzymology* / Q000254:growth & development / Q000528:radiation effects; D013696:Temperature
chemical_list: D021122:Protein Subunits; D009252:NADPH Dehydrogenase