Structural highlights
Function[IMM2_ECOLX] This protein is able to protect a cell, which harbors the plasmid ColE2 encoding colicin E2, against colicin E2. [CEA2_ECOLX] This plasmid-coded bactericidal protein is an endonuclease active on both single- and double-stranded DNA but with undefined specificity. Colicins are polypeptide toxins produced by and active against E.coli and closely related bacteria. Publication Abstract from PubMedHow proteins achieve high-affinity binding to a specific protein partner while simultaneously excluding all others is a major biological problem that has important implications for protein design. We report the crystal structure of the ultra-high-affinity protein-protein complex between the endonuclease domain of colicin E2 and its cognate immunity (Im) protein, Im2 (K(d) approximately 10(-)(15) M), which, by comparison to previous structural and biophysical data, provides unprecedented insight into how high affinity and selectivity are achieved in this model family of protein complexes. Our study pinpoints the role of structured water molecules in conjoining hotspot residues that govern stability with residues that control selectivity. A key finding is that a single residue, which in a noncognate context massively destabilizes the complex through frustration, does not participate in specificity directly but rather acts as an organizing center for a multitude of specificity interactions across the interface, many of which are water mediated. Structure of the Ultra-High-Affinity Colicin E2 DNase-Im2 Complex.,Wojdyla JA, Fleishman SJ, Baker D, Kleanthous C J Mol Biol. 2012 Mar 16;417(1-2):79-94. Epub 2012 Jan 27. PMID:22306467[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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