%0 Journal Article %A Wei, Hehong %A Dai, Jingcheng %A Xia, Ming %A Romine, Margaret F. %A Shi, Liang %A Beliav, Alex %A Tiedje, James M. %A Nealson, Kenneth H. %A Fredrickson, James K. %A Zhou, Jizhong %A Qiu, Dongru %T Functional roles of CymA and NapC in reduction of nitrate and nitrite by Shewanella putrefaciens W3-18-1 %D 2016 %J Microbiology, %V 162 %N 6 %P 930-941 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.000285 %K specificity %K electron transfer %K tetraheme cytochromes %K nitrite reduction %K Nitrate reduction %K Shewanella putrefaciens %I Microbiology Society, %X Shewanella putrefaciens W3-18-1 harbours two periplasmic nitrate reductase (Nap) gene clusters, NapC-associated nap-alpha (napEDABC) and CymA-dependent nap-beta (napDAGHB), for dissimilatory nitrate respiration. CymA is a member of the NapC/NirT quinol dehydrogenase family and acts as a hub to support different respiratory pathways, including those on iron [Fe(III)] and manganese [Mn(III, IV)] (hydr)oxide, nitrate, nitrite, fumarate and arsenate in Shewanella strains. However, in our analysis it was shown that another NapC/NirT family protein, NapC, was only involved in nitrate reduction, although both CymA and NapC can transfer quinol-derived electrons to a periplasmic terminal reductase or an electron acceptor. Furthermore, our results showed that NapC could only interact specifically with the Nap-alpha nitrate reductase while CymA could interact promiscuously with Nap-alpha, Nap-beta and the NrfA nitrite reductase for nitrate and nitrite reduction. To further explore the difference in specificity, site-directed mutagenesis on both CymA and NapC was conducted and the phenotypic changes in nitrate and nitrite reduction were tested. Our analyses demonstrated that the Lys-91 residue played a key role in nitrate reduction for quinol oxidation and the Asp-166 residue might influence the maturation of CymA. The Asp-97 residue might be one of the key factors that influence the interaction of CymA with the cytochromes NapB and NrfA. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000285