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|Title:||Crystal structure of the heteromolecular chaperone, AscE-AscG, from the type III secretion system in Aeromonas hydrophila||Authors:||Chatterjee, C.
|Issue Date:||2011||Citation:||Chatterjee, C., Kumar, S., Chakraborty, S., Tan, Y.W., Leung, K.Y., Sivaraman, J., Mok, Y.-K. (2011). Crystal structure of the heteromolecular chaperone, AscE-AscG, from the type III secretion system in Aeromonas hydrophila. PLoS ONE 6 (4) : -. ScholarBank@NUS Repository. https://doi.org/10.1371/journal.pone.0019208||Abstract:||Background: The putative needle complex subunit AscF forms a ternary complex with the chaperones AscE and AscG in the type III secretion system of Aeromonas hydrophila so as to avoid premature assembly. Previously, we demonstrated that the C-terminal region of AscG (residues 62-116) in the hetero-molecular chaperone, AscE-AscG, is disordered and susceptible to limited protease digestion. Methodology/Principal Findings: Here, we report the crystal structure of the ordered AscG1-61 region in complex with AscE at 2.4 Å resolution. Helices α2 and α3 of AscE in the AscE-AscG1-61 complex assumes a helix-turn-helix conformation in an anti-parallel fashion similar to that in apo AscE. However, in the presence of AscG, an additional N-terminal helix α1 in AscE (residues 4-12) is observed. PscG or YscG in the crystal structures of PscE-PscF-PscG or YscE-YscF-YscG, respectively, assumes a typical tetratricopeptide repeat (TPR) fold with three TPR repeats and one C-terminal capping helix. By comparison, AscG in AscE-AscG1-61 comprises three anti-parallel helices that resembles the N-terminal TPR repeats in the corresponding region of PscG or YscG in PscE-PscF-PscG or YscE-YscF-YscG. Thermal denaturation of AscE-AscG and AscE-AscG1-61 complexes demonstrates that the C-terminal disordered region does not contribute to the thermal stability of the overall complex. Conclusion/Significance: The N-terminal region of the AscG in the AscE-AscG complex is ordered and assumes a structure similar to those in the corresponding regions of PscE-PscG-PscF or YscE-YscF-YscG complexes. While the C-terminal region of AscG in the AscE-AscG complex is disordered and will assume its structure only in the presence of the substrate AscF. We hypothesize that AscE act as a chaperone of the chaperone to keep AscG in a stable but partially disordered state for interaction with AscF. © 2011 Chatterjee et al.||Source Title:||PLoS ONE||URI:||http://scholarbank.nus.edu.sg/handle/10635/115049||ISSN:||19326203||DOI:||10.1371/journal.pone.0019208|
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