Recognition between a bacterial ribonuclease, barnase, and its natural inhibitor, barstar

Guillet, V., Lapthorn, A. , Hartley, R.W. and Mauguen, Y. (1993) Recognition between a bacterial ribonuclease, barnase, and its natural inhibitor, barstar. Structure, 1(3), pp. 165-176. (doi: 10.1016/0969-2126(93)90018-C) (PMID:16100951)

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Background: Protein-protein recognition is fundamental to most biological processes. The information we have so far on the interfaces between proteins comes largely from several protease-inhibitor and antigen-antibody complexes. Barnase, a bacterial ribonuclease, and barstar, its natural inhibitor, form a tight complex which provides a good model for the study and design of protein-protein non-covalent interactions. Results: Here we report the structure of a complex between barnase and a fully functional mutant of barstar determined by X-ray analysis. Barstar is composed of three parallel α-helices stacked against a three-stranded parallel β-sheet, and sterically blocks the active site of the enzyme with an α-helix and adjacent loop. The buried surface in the interface between the two molecules totals 1630 Å2. The barnase-barstar complex is predominantly stabilized by charge interactions involving positive charges in the active site of the enzyme. Asp39 of barstar binds to the phosphate-binding site of barnase, mimicking enzyme-substrate interactions. Conclusion: The phosphate-binding site of the enzyme is the anchor point for inhibitor binding. We propose that this is also likely to be the case for other ribonuclease inhibitors.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Lapthorn, Dr Adrian
Authors: Guillet, V., Lapthorn, A., Hartley, R.W., and Mauguen, Y.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Structure
Publisher:Elsevier (Cell Press)

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