Rapid kinetics of H transport by membrane pyrophosphatase: Evidence for a "direct-coupling" mechanism.

Stress resistance-conferring membrane pyrophosphatase (mPPase) found in microbes and plants couples pyrophosphate hydrolysis with H transport out of the cytoplasm. There are two opposing views on the energy-coupling mechanism in this transporter: the pumping is associated with either pyrophosphate binding to mPPase or the hydrolysis step. We used our recently developed stopped-flow pyranine assay to measure H transport into mPPase-containing inverted membrane vesicles on the timescale of a single turnover.

Na Translocation Dominates over H-Translocation in the Membrane Pyrophosphatase with Dual Transport Specificity.

Cation-pumping membrane pyrophosphatases (mPPases; EC 7.1.3.

Acrylate Reductase of an Anaerobic Electron Transport Chain of the Marine Bacterium Shewanella woodyi.

Many microorganisms are capable of anaerobic respiration in the absence of oxygen, by using different organic compounds as terminal acceptors in electron transport chain. We identify here an anaerobic respiratory chain protein responsible for acrylate reduction in the marine bacterium Shewanella woodyi. When the periplasmic proteins of S.

A Redox-Regulated, Heterodimeric NADH:cinnamate Reductase in Vibrio ruber.

Genes of putative reductases of α,β-unsaturated carboxylic acids are abundant among anaerobic and facultatively anaerobic microorganisms, yet substrate specificity has been experimentally verified for few encoded proteins. Here, we co-produced in Escherichia coli a heterodimeric protein of the facultatively anaerobic marine bacterium Vibrio ruber (GenBank SJN56019 and SJN56021; annotated as NADPH azoreductase and urocanate reductase, respectively) with Vibrio cholerae flavin transferase. The isolated protein (named Crd) consists of the sjn56021-encoded subunit CrdB (NADH:flavin, FAD binding 2, and FMN bind domains) and an additional subunit CrdA (SJN56019, a single NADH:flavin domain) that interact via their NADH:flavin domains (Alphafold2 prediction).

Mechanism of Ion Translocation by Na+-Rhodopsin.

This review provides a brief description of the structure and transport function of the recently discovered family of retinal-containing Na+-translocating rhodopsins. The main emphasis is put on the kinetics of generation of electric potential difference in the membrane during a single transporter turnover. According to the proposed transport mechanism of Na+-rhodopsin, the driving force for the Na+ translocation from the cytoplasm is the local electric field created by the H+ movement from the Schiff base.