Conserved Histidine Adjacent to the Proximal Cluster Tunes the Anaerobic Reductive Activation of Escherichia coli Membrane-Bound [NiFe] Hydrogenase-1.

Lindsey A Flanagan,Harriet S Chidwick,Julia Walton,James W B Moir,Alison Parkin

doi:10.1002/celc.201800047

Lindsey A Flanagan, Harriet S Chidwick + Show 3 more

Open Access

https://doi.org/10.1002/celc.201800047

Copy DOI

Journal: ChemElectroChem	Publication Date: Feb 16, 2018
Citations: 4	License type: CC BY 4.0

Affiliation: University of York

Abstract

[NiFe] hydrogenases are electrocatalysts that oxidize H2 at a rapid rate without the need for precious metals. All membrane‐bound [NiFe] hydrogenases (MBH) possess a histidine residue that points to the electron‐transfer iron sulfur cluster closest (“proximal”) to the [NiFe] H2‐binding active site. Replacement of this amino acid with alanine induces O2 sensitivity, and this has been attributed to the role of the histidine in enabling the reversible O2‐induced over‐oxidation of the [Fe4S3Cys2] proximal cluster possessed by all O2‐tolerant MBH. We have created an Escherichia coli Hyd‐1 His‐to‐Ala variant and report O2‐free electrochemical measurements at high potential that indicate the histidine‐mediated [Fe4S3Cys2] cluster‐opening/closing mechanism also underpins anaerobic reactivation. We validate these experiments by comparing them to the impact of an analogous His‐to‐Ala replacement in Escherichia coli Hyd‐2, a [NiFe]‐MBH that contains a [Fe4S4] center.

Highlights

All membranebound [NiFe] hydrogenases (MBH) possess a histidine residue that points to the electron-transfer iron sulfur cluster closest
(“proximal”) to the [NiFe] H2-binding active site. Replacement of this amino acid with alanine induces O2 sensitivity, and this has been attributed to the role of the histidine in enabling the reversible O2-induced over-oxidation of the [Fe4S3Cys2] proximal cluster possessed by all O2-tolerant MBH
We have created an Escherichia coli Hyd-1 His-to-Ala variant and report O2-free electrochemical measurements at high potential that indicate the histidine-mediated [Fe4S3Cys2] cluster-opening/closing mechanism underpins anaerobic reactivation. We validate these experiments by comparing them to the impact of an analogous His-to-Ala replacement in Escherichia coli Hyd-2, a

Summary

Conserved Histidine Adjacent to the Proximal Cluster

Tunes the Anaerobic Reductive Activation of Escherichia coli Membrane-Bound [NiFe] Hydrogenase-1. All membranebound [NiFe] hydrogenases (MBH) possess a histidine residue that points to the electron-transfer iron sulfur cluster closest (“proximal”) to the [NiFe] H2-binding active site. Replacement of this amino acid with alanine induces O2 sensitivity, and this has been attributed to the role of the histidine in enabling the reversible O2-induced over-oxidation of the [Fe4S3Cys2] proximal cluster possessed by all O2-tolerant MBH. We have created an Escherichia coli Hyd-1 His-to-Ala variant and report O2-free electrochemical measurements at high potential that indicate the histidine-mediated [Fe4S3Cys2] cluster-opening/closing mechanism underpins anaerobic reactivation We validate these experiments by comparing them to the impact of an analogous His-to-Ala replacement in Escherichia coli Hyd-2, a [NiFe]-MBH that contains a [Fe4S4] center.

Department of Biology

Findings

Conflict of Interest