Structural highlights
Publication Abstract from PubMedChemotaxis is the process of sensing chemical gradients and navigating towards favourable conditions. Bacterial chemotaxis is mediated by arrays of trans-membrane chemoreceptor proteins. The most common class of chemoreceptors have periplasmic ligand-binding domains (LBDs) that detect extracellular chemical signs and transduce these signals to the downstream chemotaxis machinery. The repertoire of chemoreceptor proteins in a bacterium determines the range of environmental signals to which it can respond. Pseudomonas syringae pv. actinidiae (Psa) is a plant pathogen which causes bacterial canker of kiwifruit (Actinidia sp.). Compared to many other bacteria, Psa has a large number of chemoreceptors encoded in its genome (43) and most of these remain uncharacterized. A previous study identified PscC as a potential chemoreceptor for l-proline and other amino acid ligands. Here, we have characterized the interaction of PscC-LBD with l-proline using a combination of isothermal titration calorimetry (ITC) and X-ray crystallography. ITC confirmed direct binding of l-proline to PscC-LBD with KD value of 5.0 muM. We determined the structure of PscC-LBD in complex with l-proline. Our structural analysis showed that PscC-LBD adopts similar double-CACHE fold to several other amino acid chemoreceptors. A comparison of the PscC-LDB to other dCACHE structures highlights residues in the binding cavity which contribute to its ligand specificity. Structure of a double CACHE chemoreceptor ligand-binding domain from Pseudomonas syringae provides insights into the basis of proline recognition.,Ehrhardt MKG, Gerth ML, Johnston JM Biochem Biophys Res Commun. 2021 Apr 16;549:194-199. doi:, 10.1016/j.bbrc.2021.02.090. Epub 2021 Mar 12. PMID:33721671[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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