Abstract
The crystal structures of BB2672 and SPO0826 were determined to resolutions of 1.7 and 2.1 Å by single-wavelength anomalous dispersion and multiple-wavelength anomalous dispersion, respectively, using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). These proteins are the first structural representatives of the PF06684 (DUF1185) Pfam family. Structural analysis revealed that both structures adopt a variant of the Bacillus chorismate mutase fold (BCM). The biological unit of both proteins is a hexamer and analysis of homologs indicates that the oligomer interface residues are highly conserved. The conformation of the critical regions for oligomerization appears to be dependent on pH or salt concentration, suggesting that this protein might be subject to environmental regulation. Structural similarities to BCM and genome-context analysis suggest a function in amino-acid synthesis.
Highlights
To extend the structural coverage of proteins of unknown function, we targeted Pfam protein family PF06684 and determined the crystal structures of two representative members
The BB2672 gene of Bordetella bronchiseptica, which is a causative agent of infectious bronchitis in domestic mammals, encodes a protein with a molecular weight of 20.9 kDa and a calculated isoelectric point of 7.1
Analysis of the BB2672 crystallographic hexamer reveals a trimer of dimers, with two distinct types of dimerization interface created by an extra N-terminal strand and a -hairpin insertion between strands 3 and 4 in the core Bacillus chorismate mutase fold (BCM)-like fold
Summary
To extend the structural coverage of proteins of unknown function, we targeted Pfam protein family PF06684 (domain of unknown function 1185; DUF1185) and determined the crystal structures of two representative members. The BB2672 gene of Bordetella bronchiseptica, which is a causative agent of infectious bronchitis in domestic mammals, encodes a protein with a molecular weight of 20.9 kDa (residues 1–192) and a calculated isoelectric point of 7.1. The SPO0826 gene of the marine -proteobacterium Silicibacter pomeroyi encodes a protein with a molecular weight of 20.5 kDa (residues 1–193) and a calculated isoelectric point of 6.2. Analysis of the BB2672 crystallographic hexamer reveals a trimer of dimers, with two distinct types of dimerization interface created by an extra N-terminal strand and a -hairpin insertion between strands 3 and 4 in the core BCM-like fold. The smaller interface at the N-terminus could present a potential ligand-binding site for the DUF1185 family, the genetic context of which supports a role in amino-acid metabolism
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