TCB Publications - Abstract

Pius S. Padayatti, Josephine H. Leung, Paween Mahinthichaichan, Emad Tajkhorshid, Andrii Ishchenko, Vadim Cherezov, S. Michael Soltis, J. Baz Jackson, C. David Stout, Robert B. Gennis, and Qinghai Zhang. Critical role of water molecules in proton translocation by the membrane-bound transhydrogenase. Structure, 25:1111-1119, 2017. (PMC: PMC5524145)

PADA2017-ET The nicotinamide nucleotide transhydrogenase (TH) is an integral membrane enzyme that uses the proton-motive force to drive hydride transfer from NADH to NADP$^+$ in bacteria and eukaryotes. Here we solved a 2.2-Åcrystal structure of the TH transmembrane domain (Thermus thermophilus) at pH 6.5. This structure exhibits conformational changes of helix positions from a previous structure solved at pH 8.5, and reveals internal water molecules interacting with residues implicated in proton translocation. Together with molecular dynamics simulations, we show that transient water flows across a narrow pore and a hydrophobic “dry” region in the middle of the membrane channel, with key residues His42$^{\alpha 2}$ (chain A) being protonated and Thr214$^{\beta}$ (chain B) displaying a conformational change, respectively, to gate the channel access to both cytoplasmic and periplasmic chambers. Mutation of Thr214$^{\beta}$ to Ala deactivated the enzyme. These data provide new insights into the gating mechanism of proton translocation in TH.

Download Full Text

The manuscripts available on our site are provided for your personal use only and may not be retransmitted or redistributed without written permissions from the paper's publisher and author. You may not upload any of this site's material to any public server, on-line service, network, or bulletin board without prior written permission from the publisher and author. You may not make copies for any commercial purpose. Reproduction or storage of materials retrieved from this web site is subject to the U.S. Copyright Act of 1976, Title 17 U.S.C.

Download full text: Request a Copy, Supplemental Material (197.9KB) - Supplemental PDF, Supplemental Material - Supplemental Movie, Journal