Open AccessLysozyme contamination facilitates crystallization of a heterotrimeric cortactin–Arg–lysozyme complex
Author(s) -
Liu Weizhi,
MacGrath Stacey M.,
Koleske Anthony J.,
Boggon Titus J.
Publication year - 2012
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309111056132
Subject(s) - lysozyme , heterotrimeric g protein , cortactin , chemistry , crystallization , crystallography , biochemistry , g protein , receptor , cytoskeleton , cell , organic chemistry
Crystallization of contaminating proteins is a frequently encountered problem for macromolecular crystallographers. In this study, an attempt was made to obtain a binary cocrystal structure of the SH3 domain of cortactin and a 17‐residue peptide from the Arg nonreceptor tyrosine kinase encompassing a P xx P xx P xx P (P xx P1) motif. However, cocrystals could only be obtained in the presence of trace amounts of a contaminating protein. A structure solution obtained by molecular replacement followed by ARP / wARP automatic model building allowed a `sequence‐by‐crystallography' approach to discover that the contaminating protein was lysozyme. This 1.65 Å resolution crystal structure determination of a 1:1:1 heterotrimeric complex of Arg, cortactin and lysozyme thus provides an unusual `caveat emptor' warning of the dangers that underpurified proteins harbor for macromolecular crystallographers.