TY - JOUR
T1 - DsrL mediates electron transfer between NADH and rDsrAB in Allochromatium vinosum
AU - Löffler, Maria
AU - Feldhues, Julia
AU - Venceslau, Sofia S.
AU - Kammler, Lydia
AU - Grein, Fabian
AU - Pereira, Inês A.C.
AU - Dahl, Christiane
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Dissimilatory sulphite reductase DsrAB occurs in sulphate/sulphite-reducing prokaryotes, in sulphur disproportionators and also in sulphur oxidizers, where it functions in reverse. Predictions of physiological traits in metagenomic studies relying on the presence of dsrAB, other dsr genes or combinations thereof suffer from the lack of information on crucial Dsr proteins. The iron–sulphur flavoprotein DsrL is an example of this group. It has a documented essential function during sulphur oxidation and was recently also found in some metagenomes of probable sulphate and sulphite reducers. Here, we show that DsrL and reverse acting rDsrAB can form a complex and are copurified from the phototrophic sulphur oxidizer Allochromatium vinosum. Recombinant DsrL exhibits NAD(P)H:acceptor oxidoreductase activity with a strong preference for NADH over NADPH. In vitro, the rDsrABL complex effectively catalyses NADH-dependent sulphite reduction, which is strongly enhanced by the sulphur-binding protein DsrC. Our work reveals NAD+ as suitable in vivo electron acceptor for sulphur oxidation in organisms operating the rDsr pathway and points to reduced nicotinamide adenine dinucleotides as electron donors for sulphite reduction in sulphate/sulphite-reducing prokaryotes that contain DsrL. In addition, dsrL cannot be used as a marker distinguishing sulphate/sulphite reducers and sulphur oxidizers in metagenomic studies without further analysis.
AB - Dissimilatory sulphite reductase DsrAB occurs in sulphate/sulphite-reducing prokaryotes, in sulphur disproportionators and also in sulphur oxidizers, where it functions in reverse. Predictions of physiological traits in metagenomic studies relying on the presence of dsrAB, other dsr genes or combinations thereof suffer from the lack of information on crucial Dsr proteins. The iron–sulphur flavoprotein DsrL is an example of this group. It has a documented essential function during sulphur oxidation and was recently also found in some metagenomes of probable sulphate and sulphite reducers. Here, we show that DsrL and reverse acting rDsrAB can form a complex and are copurified from the phototrophic sulphur oxidizer Allochromatium vinosum. Recombinant DsrL exhibits NAD(P)H:acceptor oxidoreductase activity with a strong preference for NADH over NADPH. In vitro, the rDsrABL complex effectively catalyses NADH-dependent sulphite reduction, which is strongly enhanced by the sulphur-binding protein DsrC. Our work reveals NAD+ as suitable in vivo electron acceptor for sulphur oxidation in organisms operating the rDsr pathway and points to reduced nicotinamide adenine dinucleotides as electron donors for sulphite reduction in sulphate/sulphite-reducing prokaryotes that contain DsrL. In addition, dsrL cannot be used as a marker distinguishing sulphate/sulphite reducers and sulphur oxidizers in metagenomic studies without further analysis.
UR - http://www.scopus.com/inward/record.url?scp=85077905502&partnerID=8YFLogxK
U2 - 10.1111/1462-2920.14899
DO - 10.1111/1462-2920.14899
M3 - Article
C2 - 31854015
AN - SCOPUS:85077905502
VL - 22
SP - 783
EP - 795
JO - Environmental Microbiology
JF - Environmental Microbiology
SN - 1462-2912
IS - 2
ER -