Linked Life Data

9718299

Source:http://linkedlifedata.com/resource/pubmed/id/9718299

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
34
pubmed:dateCreated
1998-9-14
pubmed:abstractText
The immunity protein Im2 can bind and inhibit the noncognate endonuclease domain of the bacterial toxin colicin E9 with a Kd of 19 nM, 6 orders of magnitude weaker than that of the cognate immunity protein Im9 with which it shares 68% sequence identity. Previous work from our laboratory has shown that the specificity differences of these four-helix immunity proteins is due almost entirely to helix II which is largely variable in sequence in the immunity protein family. From alanine scanning mutagenesis of Im9 in conjunction with high-field NMR data, a dual recognition model for colicin-immunity protein specificity has been proposed whereby the conserved residues of helix III of the immunity protein act as the anchor of the endonuclease binding site while the variable residues of helix II control the specificity of the protein-protein interaction. In this work, we identify three residues (at positions 33, 34, and 38) in helix II which define the specificity differences of Im2 and Im9 for colicin E9 and, using alanine mutagenesis of the putative endonuclease binding surface of Im2, compare the distribution of binding energies for conserved and nonconserved sites in both immunity proteins. This comparison highlights the conserved residues of both Im2 and Im9 as the major determinants of E9 DNase binding energy. Conversely, the nonconserved, specificity-determining residues only contribute to the E9 DNase binding energy in the cognate Im9 protein, while in the noncognate immunity protein Im2, they either destabilize the complex or do not contribute to the binding energy. This comparative alanine scan of two immunity proteins therefore supports the dual recognition mechanism of selectivity in colicin-immunity protein interactions and provides a basis for understanding specificity in other protein-protein interaction systems involving structurally conserved protein families.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11771-9
pubmed:dateRevised
2009-9-29
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Dual recognition and the role of specificity-determining residues in colicin E9 DNase-immunity protein interactions.
pubmed:affiliation
Schools of Biological and Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, U.K.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't