6RP2

Threonine to Cysteine (T225C) variant of E coli hydrogenase-1

Summary for 6RP2

• Entry DOI: 10.2210/pdb6rp2/pdb
• Descriptor: Hydrogenase-1 small chain, NICKEL (II) ION, MAGNESIUM ION, ... (13 entities in total)
• Functional Keywords: [nife]-hydrogenase, hydrogen production, fes clusters, nanoclusters, oxidoreductase
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 4
• Total formula weight: 203979.10

Authors

Carr, S.B.,Armstrong, F.A.,Zhang, L. (deposition date: 2019-05-13, release date: 2020-03-25, Last modification date: 2020-07-29)

Primary citation

Zhang, L.,Morello, G.,Carr, S.B.,Armstrong, F.A.
Aerobic Photocatalytic H2Production by a [NiFe] Hydrogenase Engineered to Place a Silver Nanocluster in the Electron Relay.
J.Am.Chem.Soc., 142:12699-12707, 2020

PubMed Abstract: Hydrogenase-1 (Hyd-1) from poses a conundrum regarding the properties of electrocatalytic reversibility and associated bidirectionality now established for many redox enzymes. Its excellent H-oxidizing activity begins only once a substantial overpotential is applied, and it cannot produce H. A major reason for its unidirectional behavior is that the reduction potentials of its electron-relaying FeS clusters are too positive relative to the 2H/H couple at neutral pH; consequently, electrons held within the enzyme lack the energy to drive H production. However, Hyd-1 is O-tolerant and even functions in air. Changing a tyrosine (Y) or threonine (T), located on the protein surface within 10 Å of the distal [4Fe-4S] and medial [3Fe-4S] clusters, to cysteine (C), allows site-selective attachment of a silver nanocluster (AgNC), the reduced or photoexcited state of which is a powerful reductant. The AgNC provides a new additional redox site, capturing externally supplied electrons with sufficiently high energy to drive H production. Assemblies of Y'227C (or T'225C) with AgNCs/PMAA (PMAA = polymethyl acrylate templating several AgNC) are also electroactive for H production at a TiO electrode. A colloidal system for visible-light photo-H generation is made by building the hybrid enzyme into a heterostructure with TiO and graphitic carbon nitride (g-CN), the resulting scaffold promoting uptake of electrons excited at the AgNC. Each hydrogenase produces 40 molecules of H per second and sustains 20% activity in air.

PubMed: 32579353
DOI: 10.1021/jacs.0c04302

Experimental method

X-RAY DIFFRACTION (1.35 Å)