7NTE

The structure of an open conformation of the SBP TarP_Csal

Summary for 7NTE

• Entry DOI: 10.2210/pdb7nte/pdb
• Related: 7NQG 7NR2 7NRA 7NRR 7NSW 7NTD
• Descriptor: TRAP dicarboxylate transporter-DctP subunit, MAGNESIUM ION (3 entities in total)
• Functional Keywords: trap transporter, solute binding protein, periplasmic, hydroxycinnamate, lignin, transport protein
• Biological source: Chromohalobacter salexigens (strain ATCC BAA-138 / DSM 3043 / CIP 106854 / NCIMB 13768 / 1H11)
• Total number of polymer chains: 2
• Total formula weight: 74680.53

Authors

Bisson, C.,Salmon, R.C.,West, L.,Rafferty, J.B.,Hitchcock, A.,Thomas, G.H.,Kelly, D.J. (deposition date: 2021-03-09, release date: 2021-10-06, Last modification date: 2024-01-31)

Primary citation

Bisson, C.,Salmon, R.C.,West, L.,Rafferty, J.B.,Hitchcock, A.,Thomas, G.H.,Kelly, D.J.
The structural basis for high-affinity uptake of lignin-derived aromatic compounds by proteobacterial TRAP transporters.
Febs J., 289:436-456, 2022

PubMed 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. Whilst 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 palustris can grow on a range of phenylpropanoid monomers and is a model organism for studying their uptake and breakdown. R. 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 R. 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.

PubMed: 34375507
DOI: 10.1111/febs.16156

Experimental method

X-RAY DIFFRACTION (1.6 Å)