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1m5q
From Proteopedia
Crystal structure of a novel Sm-like archaeal protein from Pyrobaculum aerophilum
Overview
To better understand the roles of Sm proteins in forming the cores of many RNA-processing ribonucleoproteins, we determined the crystal structure of an atypical Sm-like archaeal protein (SmAP3) in which the conserved Sm domain is augmented by a previously uncharacterized, mixed alpha/beta C-terminal domain. The structure reveals an unexpected SmAP3 14-mer that is perforated by a cylindrical pore and is bound to 14 cadmium (Cd(2+)) ions. Individual heptamers adopt either "apical" or "equatorial" conformations that chelate Cd(2+) differently. SmAP3 forms supraheptameric oligomers (SmAP3)(n = 7,14,28) in solution, and assembly of the asymmetric 14-mer is modulated by differential divalent cation-binding in apical and equatorial subunits. Phylogenetic and sequence analyses substantiate SmAP3s as a unique subset of SmAPs. These results distinguish SmAP3s from other Sm proteins and provide a model for the structure and properties of Sm proteins >100 residues in length, e.g., several human Sm proteins.
About this Structure
1M5Q is a Single protein structure of sequence from Pyrobaculum aerophilum. Full crystallographic information is available from OCA.
Reference
Structure and assembly of an augmented Sm-like archaeal protein 14-mer., Mura C, Phillips M, Kozhukhovsky A, Eisenberg D, Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4539-44. Epub 2003 Mar 31. PMID:12668760 Page seeded by OCA on Sat May 3 00:40:01 2008
