3UEP

Crystal structure of YscQ-C from Yersinia pseudotuberculosis

Summary for 3UEP

• Entry DOI: 10.2210/pdb3uep/pdb
• Descriptor: YscQ-C, type III secretion protein (2 entities in total)
• Functional Keywords: type iii secretion protein, cytosol, protein transport
• Biological source: Yersinia pseudotuberculosis
• Total number of polymer chains: 2
• Total formula weight: 21404.27

Authors

Bzymek, K.P.,Ghosh, P. (deposition date: 2011-10-31, release date: 2012-04-04, Last modification date: 2024-04-03)

Primary citation

Bzymek, K.P.,Hamaoka, B.Y.,Ghosh, P.
Two Translation Products of Yersinia yscQ Assemble To Form a Complex Essential to Type III Secretion.
Biochemistry, 51:1669-1677, 2012

PubMed Abstract: The bacterial flagellar C-ring is composed of two essential proteins, FliM and FliN. The smaller protein, FliN, is similar to the C-terminus of the larger protein, FliM, both being composed of SpoA domains. While bacterial type III secretion (T3S) systems encode many proteins in common with the flagellum, they mostly have a single protein in place of FliM and FliN. This protein resembles FliM at its N-terminus and is as large as FliM but is more like FliN at its C-terminal SpoA domain. We have discovered that a FliN-sized cognate indeed exists in the Yersinia T3S system to accompany the FliM-sized cognate. The FliN-sized cognate, YscQ-C, is the product of an internal translation initiation site within the locus encoding the FliM-sized cognate YscQ. Both intact YscQ and YscQ-C were found to be required for T3S, indicating that the internal translation initiation site, which is conserved in some but not all YscQ orthologs, is crucial for function. The crystal structure of YscQ-C revealed a SpoA domain that forms a highly intertwined, domain-swapped homodimer, similar to those observed in FliN and the YscQ ortholog HrcQ(B). A single YscQ-C homodimer associated reversibly with a single molecule of intact YscQ, indicating conformational differences between the SpoA domains of intact YscQ and YscQ-C. A "snap-back" mechanism suggested by the structure can account for this. The 1:2 YscQ-YscQ-C complex is a close mimic of the 1:4 FliM-FliN complex and the likely building block of the putative Yersinia T3S system C-ring.

PubMed: 22320351
DOI: 10.1021/bi201792p

Experimental method

X-RAY DIFFRACTION (2.25 Å)