Biology subjects

Heider, J.

Publications and source records attributed to Heider, J..

2 recordsLinked to original sources

bioRxiv2023

A bacterial tungsten-containing aldehyde oxidoreductase forms an enzymatic decorated protein nanowire

Aldehyde oxidoreductases (AOR) are tungsten enzymes catalysing the oxidation of many different aldehydes to the corresponding carboxylic acids. In contrast to other known AORs, the enzyme from the denitrifying betaproteobacterium Aromatoleum aromaticum (AORAa) consists of three different subunits (AorABC) and utilizes NAD as electron acceptor. Here we reveal that the enzyme forms filaments of repeating AorAB protomers which are capped by a single NAD-binding AorC subunit, based on solving its structure via cryo-electron microscopy. The polyferredoxin-like subunit AorA oligomerizes to an electron-conducting nanowire that is decorated with enzymatically active and W-cofactor (W-co) containing AorB subunits. Our structure further reveals the binding mode of the native substrate benzoate in the AorB active site. This, together with QM:MM-based modelling for the coordination of the W-co, enables formulation of catalytic mechanism hypothesis that paves the way for further engineering of AOR for applications in synthetic biology and biotechnology.

biochemistry↗

bioRxiv2022

Structure of the membrane-bound formate hydrogenlyase complex from Escherichia coli

The prototypical hydrogen-producing enzyme, the membrane-bound formate hydrogen lyase (FHL) complex from Escherichia coli, links formate oxidation at a molybdopterin-containing formate dehydrogenase to proton reduction at a [NiFe] hydrogenase. It is of intense interest due to its ability to efficiently produce H2 during fermentation, its reversibility, allowing H2-dependent CO2 reduction, and its evolutionary link to respiratory complex I. FHL has been studied for over a century, but its atomic structure remains unknown. Here we report cryo-EM structures of FHL in its aerobically- and anaerobically-isolated forms at resolutions reaching 2.6 [A]. This includes well-resolved density for conserved loops linking the soluble and membrane arms believed to be essential in coupling enzymatic turnover to ion translocation across the membrane in the complex I superfamily. We describe an unpredicted metal-binding site near the interface of FdhF and HycF subunits that may play a role in preventing reverse activity in vivo, and evaluate possible structural determinants of the bias toward hydrogen production over its oxidation.

biophysics↗