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Acta Crystallogr Sect F Struct Biol Cryst Commun. 2010 Oct 1;66(Pt 10):1245-53. doi: 10.1107/S1744309109042481. Epub 2009 Dec 8.

Open and closed conformations of two SpoIIAA-like proteins (YP_749275.1 and YP_001095227.1) provide insights into membrane association and ligand binding.

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1
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.

Abstract

The crystal structures of the proteins encoded by the YP_749275.1 and YP_001095227.1 genes from Shewanella frigidimarina and S. loihica, respectively, have been determined at 1.8 and 2.25 Å resolution, respectively. These proteins are members of a novel family of bacterial proteins that adopt the α/β SpoIIAA-like fold found in STAS and CRAL-TRIO domains. Despite sharing 54% sequence identity, these two proteins adopt distinct conformations arising from different dispositions of their α2 and α3 helices. In the `open' conformation (YP_001095227.1), these helices are 15 Å apart, leading to the creation of a deep nonpolar cavity. In the `closed' structure (YP_749275.1), the helices partially unfold and rearrange, occluding the cavity and decreasing the solvent-exposed hydrophobic surface. These two complementary structures are reminiscent of the conformational switch in CRAL-TRIO carriers of hydrophobic compounds. It is suggested that both proteins may associate with the lipid bilayer in their `open' monomeric state by inserting their amphiphilic helices, α2 and α3, into the lipid bilayer. These bacterial proteins may function as carriers of nonpolar substances or as interfacially activated enzymes.

PMID:
20944218
PMCID:
PMC2954212
DOI:
10.1107/S1744309109042481
[Indexed for MEDLINE]
Free PMC Article

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