Structural highlights
Publication Abstract from PubMedAssembly line polyketide synthases (PKSs) are large multimodular enzymes responsible for the biosynthesis of diverse antibiotics in bacteria. Structural and mechanistic analysis of these megasynthases can benefit from the discovery of reagents that recognize individual domains or linkers in a site-specific manner. Monoclonal antibodies have not only proven themselves as premier tools in analogous applications, but they also have the added benefit of constraining the conformational flexibility of their targets in unpredictable but often useful ways. Here we have exploited a library based on the naive human antibody repertoire to discover a Fab (3A6) that recognizes the terminal thioesterase (TE) domain of the 6-deoxyerythronolide B synthase with high specificity. Biochemical assays were used to verify that 3A6 binding does not inhibit enzyme turnover. The co-crystal structure of the TE-3A6 complex was solved at 2.45 A resolution, resulting in atomic characterization of this protein-protein recognition mechanism. Fab binding had minimal effects on structural integrity of the TE. In turn, these insights were used to interrogate via small-angle X-ray scattering the solution-phase conformation of 3A6 complexed to a catalytically competent PKS module and bimodule. Altogether, we have developed a high affinity monoclonal antibody tool that recognizes the TE domain of the 6-deoxyerythronolide B synthase while maintaining its native function. Discovery and characterization of a thioesterase-specific monoclonal antibody that recognizes the 6-deoxyerythronolide B synthase.,Li X, Sevillano N, La Greca F, Hsu J, Mathews II, Matsui T, Craik CS, Khosla C Biochemistry. 2018 Oct 5. doi: 10.1021/acs.biochem.8b00886. PMID:30289692[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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