6VAP

Structure of the type II thioesterase BorB from the borrelidin biosynthetic cluster

Summary for 6VAP

• Entry DOI: 10.2210/pdb6vap/pdb
• Descriptor: Thioesterase (2 entities in total)
• Functional Keywords: thioesterase, biosynthetic protein
• Biological source: Streptomyces sp. WAC02707
• Total number of polymer chains: 2
• Total formula weight: 58774.40

Authors

Pereira, J.H.,Curran, S.C.,Baluyot, M.-J.,Lake, J.,Putz, H.,Rosenburg, D.,Keasling, J.,Adams, P.D. (deposition date: 2019-12-17, release date: 2020-05-06, Last modification date: 2023-10-11)

Primary citation

Curran, S.C.,Pereira, J.H.,Baluyot, M.J.,Lake, J.,Puetz, H.,Rosenburg, D.J.,Adams, P.,Keasling, J.D.
Structure and Function of BorB, the Type II Thioesterase from the Borrelidin Biosynthetic Gene Cluster.
Biochemistry, 59:1630-1639, 2020

PubMed Abstract: α/β hydrolases make up a large and diverse protein superfamily. In natural product biosynthesis, -acting thioesterase α/β hydrolases can terminate biosynthetic assembly lines and release products by hydrolyzing or cyclizing the biosynthetic intermediate. Thioesterases can also act in , removing aberrant intermediates and restarting stalled biosynthesis. Knockout of this "editing" function leads to reduced product titers. The borrelidin biosynthetic gene cluster from Tü4055 contains a hitherto uncharacterized stand-alone thioesterase, . In this work, we demonstrate that purified BorB cleaves acyl substrates with a preference for propionate, which supports the hypothesis that it is also an editing thioesterase. The crystal structure of BorB shows a wedgelike hydrophobic substrate binding crevice that limits substrate length. To investigate the structure-function relationship, we made chimeric BorB variants using loop regions from characterized homologues with different specificities. BorB chimeras slightly reduced activity, arguing that the modified region is a not major determinant of substrate preference. The structure-function relationships described here contribute to the process of elimination for understanding thioesterase specificity and, ultimately, engineering and applying -acting thioesterases in biosynthetic assembly lines.

PubMed: 32250597
DOI: 10.1021/acs.biochem.0c00126

Experimental method

X-RAY DIFFRACTION (1.93 Å)