期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：52
页码：15012-15017
DOI：10.1073/pnas.1600188113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThis article reports the computational design of a threefold symmetric, self-assembling protein homotrimer containing a highly stable noncanonical amino acid-mediated metal complex within the protein interface. To achieve this result, recently developed protein-protein interface design methods were extended to include a metal-chelating noncanonical amino acid containing a bipyridine functional group in the design process. Bipyridine metal complexes can give rise to photochemical properties that would be impossible to achieve with naturally occurring amino acids alone, suggesting that the methods reported here could be used to generate novel photoactive proteins. Metal-chelating heteroaryl small molecules have found widespread use as building blocks for coordination-driven, self-assembling nanostructures. The metal-chelating noncanonical amino acid (2,2'-bipyridin-5yl)alanine (Bpy-ala) could, in principle, be used to nucleate specific metalloprotein assemblies if introduced into proteins such that one assembly had much lower free energy than all alternatives. Here we describe the use of the Rosetta computational methodology to design a self-assembling homotrimeric protein with [Fe(Bpy-ala)3]2+ complexes at the interface between monomers. X-ray crystallographic analysis of the homotrimer showed that the design process had near-atomic-level accuracy: The all-atom rmsd between the design model and crystal structure for the residues at the protein interface is [~]1.4 [IMG]f1.gif" ALT="A" BORDER="0">. These results demonstrate that computational protein design together with genetically encoded noncanonical amino acids can be used to drive formation of precisely specified metal-mediated protein assemblies that could find use in a wide range of photophysical applications.
关键词：computational protein design ; noncanonical amino acids ; metalloproteins ; protein self-assembly
