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The structural basis for high‐affinity uptake of lignin‐derived aromatic compounds by proteobacterial TRAP transporters

DOI: 10.1111/febs.16156 DOI Help

Authors: Claudine Bisson (TThe University of Sheffield; King’s College London) , Robert C. Salmon (The University of Sheffield) , Laura West (University of York) , John B. Rafferty (The University of Sheffield) , Andrew Hitchcock (The University of Sheffield) , Gavin H. Thomas (University of York) , David J. Kelly (The University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Febs Journal

State: Published (Approved)
Published: August 2021
Diamond Proposal Number(s): 8987

Abstract: The organic polymer lignin is a component of plant cell walls, which like (hemi)-cellulose is highly abundant in nature and relatively resistant to degradation. However, extracellular enzymes released by natural microbial consortia can cleave the β-aryl ether linkages in lignin, releasing monoaromatic phenylpropanoids that can be further catabolised by diverse species of bacteria. Biodegradation of lignin is therefore important in global carbon cycling, and its natural abundance also makes it an attractive biotechnological feedstock for the industrial production of commodity chemicals. While the pathways for degradation of lignin-derived aromatics have been extensively characterised, much less is understood about how they are recognised and taken up from the environment. The purple phototrophic bacterium Rhodopseudomonas (Rps.) palustris can grow on a range of phenylpropanoid monomers and is a model organism for studying their uptake and breakdown. Rps. palustris encodes a tripartite ATP-independent periplasmic (TRAP) transporter (TarPQM) linked to genes encoding phenylpropanoid-degrading enzymes. The periplasmic solute binding protein component of this transporter, TarP, has previously been shown to bind aromatic substrates. Here, we determine the high-resolution crystal structure of TarP from Rps. palustris as well as the structures of homologous proteins from the salt marsh bacterium Sagittula stellata and the halophile Chromohalobacter salexigens, which also grow on lignin-derived aromatics. In combination with tryptophan fluorescence ligand-binding assays, our ligand-bound co-crystal structures reveal the molecular basis for high-affinity recognition of phenylpropanoids by these TRAP transporters, which have potential for improving uptake of these compounds for biotechnological transformations of lignin.

Journal Keywords: Chromohalobacter salexigens; hydroxycinnamate; Rhodopseudomonas palustris; Sagittula stellata; Tripartite ATP-independent periplasmic transporter

Diamond Keywords: Bacteria

Subject Areas: Biology and Bio-materials

Instruments: I02-Macromolecular Crystallography , I03-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength) , I04-Macromolecular Crystallography

Added On: 12/08/2021 15:47

Discipline Tags:

Engineering & Technology Biotechnology Life Sciences & Biotech Biotech & Biological Systems Structural biology

Technical Tags:

Diffraction Macromolecular Crystallography (MX)