NdhP is an exclusive subunit of large complex of NADPH dehydrogenase essential to stabilize the complex in Synechocystis sp. strain PCC 6803.
Two major complexes of NADPH dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1 and NdhF1, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, cyclic electron transport around photosystem I, and CO2 acquisition. Two mutants sensitive to high light for growth and impaired in NDH-1-mediated cyclic electron transfer were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in sml0013 encoding NdhP, a single transmembrane small subunit of the NDH-1 complex. During prolonged incubation of the wild type thylakoid membrane with n-dodecyl β-d-maltoside (DM), about half of the NDH-1L was disassembled to NDH-1M and the rest decomposed completely without forming NDH-1M. In the ndhP deletion mutant (ΔndhP), disassembling of NDH-1L to NDH-1M occurred even on ice, and decomposition to a small piece occurred at room temperature much faster than in the wild type. Deletion of the C-terminal tail of NdhP gave the same result. The C terminus of NdhP was tagged by YFP-His6. Blue native gel electrophoresis of the DM-treated thylakoid membrane of this strain and Western analysis using the antibody against GFP revealed that NdhP-YFP-His6 was exclusively confined to NDH-1L. During prolonged incubation of the thylakoid membrane of the tagged strain with DM at room temperature, NDH-1L was partially disassembled to NDH-1M and the 160-kDa band containing NdhP-YFP-His6 and possibly NdhD1 and NdhF1. We therefore conclude that NdhP, especially its C-terminal tail, is essential to assemble NdhD1 and NdhF1 and stabilize the NDH-1L complex.
From the College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China and.
Jingsong
J
Zhang
From the College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China and.
Fudan
F
Gao
From the College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China and.
Jiaohong
J
Zhao
the Bioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Teruo
T
Ogawa
From the College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China and.
Quanxi
Q
Wang
From the College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China and wma@shnu.edu.cn cyanoma@hotmail.com.
Weimin
W
Ma
D000595:Amino Acid Sequence; D019069:Cell Respiration; D004579:Electron Transport; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D009252:NADPH Dehydrogenase / Q000737:chemistry*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D017384:Sequence Deletion; D046939:Synechocystis / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism
D045331:Photosystem I Protein Complex; D021122:Protein Subunits; D009252:NADPH Dehydrogenase
Cyanobacteria; Electron Transfer Complex; Membrane Enzyme; Mutant; NDH-1L Complex; NDH-CET; NdhP; Photosynthesis; Stabilization; Synechocystis 6803