InterPro domain: IPR021659

NdhS/CRR31 (chlororespiratory reduction 31) is a subunit of the chloroplast NADH dehydrogenase-like (NDH) complex [ 1 ]. It is also a subunit of the cyanobacterial NDH-1 complex [ 2 , 3 ]. NAD(P)H-oxidizing subunits have not been found in chloroplasts or cyanobacteria, where ferredoxin is probably the electron donor. NdhS contributes to the formation of a ferredoxin binding site of NDH [ 4 ] and is necessary for high affinity binding of ferredoxin [ 4 ].

The cyanobacterial NDH-1 complex, also known as NADPH:plastoquinone oxidoreductase or type I NAD(P)H dehydrogenase, is involved in plastoquinone reduction and cyclic electron transfer (CET) around photosystem I. The chloroplast NDH is more similar to cyanobacterial NDH-1, which is believed to be the origin of chloroplast NDH, than to mitochondrial NADH dehydrogenase present in the same species [ 5 , 6 ]. The NDH complexes of chloroplasts, however, contain many subunits that are absent from cyanobacterial NDH-1 complexes.

1. An Src homology 3 domain-like fold protein forms a ferredoxin binding site for the chloroplast NADH dehydrogenase-like complex in Arabidopsis. Plant Cell 23, 1480-93
2. Identification of novel Ssl0352 protein (NdhS), essential for efficient operation of cyclic electron transport around photosystem I, in NADPH:plastoquinone oxidoreductase (NDH-1) complexes of Synechocystis sp. PCC 6803. J. Biol. Chem. 286, 36992-7001
3. NDH-1L interacts with ferredoxin via the subunit NdhS in Thermosynechococcus elongatus. Photosyn. Res. 126, 341-9
4. In planta mutagenesis of Src homology 3 domain-like fold of NdhS, a ferredoxin-binding subunit of the chloroplast NADH dehydrogenase-like complex in Arabidopsis: a conserved Arg-193 plays a critical role in ferredoxin binding. J. Biol. Chem. 288, 36328-37
5. Structure of the chloroplast NADH dehydrogenase-like complex: nomenclature for nuclear-encoded subunits. Plant Cell Physiol. 52, 1560-8
6. Cyanobacterial NDH-1 complexes: novel insights and remaining puzzles. Biochim. Biophys. Acta 1807, 935-44