Lysozyme contamination facilitates crystallization of a heterotrimeric cortactin-Arg-lysozyme complex.
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 PxxPxxPxxP (PxxP1) 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.
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
Weizhi
W
Liu
Stacey M
SM
MacGrath
Anthony J
AJ
Koleske
Titus J
TJ
Boggon
D000818:Animals; D001120:Arginine / Q000737:chemistry; D051356:Cortactin / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D051379:Mice; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
D051356:Cortactin; D001120:Arginine; D009113:Muramidase