Download MendeleyCombination of two separate binding domains defines stoichiometry between type III secretion system chaperone IpgC and translocator protein IpaB
Lokareddy, R.K., Lunelli, M., Eilers, B., Wolter, V., Kolbe, M.(2010) J Biol Chem 285: 39965-39975
- PubMed: 20937829
- DOI: https://doi.org/10.1074/jbc.M110.135616
- Primary Citation of Related Structures:
3GZ2 - PubMed Abstract:
Type III secretion systems (TTSSs) utilized by enteropathogenic bacteria require the presence of small, acidic virulence-associated chaperones for effective host cell infection. We adopted a combination of biochemical and cellular techniques to define the chaperone binding domains (CBDs) in the translocators IpaB and IpaC associated with the chaperone IpgC from Shigella flexneri. We identified a novel CBD in IpaB and furthermore precisely mapped the boundaries of the CBDs in both translocator proteins. In IpaC a single binding domain associates with IpgC. In IpaB, we show that the binding of the newly characterized CBD is essential in maintaining the ternary arrangement of chaperone-translocator complex. This hitherto unknown function is reflected in the co-crystal structure as well, with an IpgC dimer bound to an IpaB fragment comprising both CBDs. Moreover, in the absence of this novel CBD the IpaB/IpgC complex aggregates. This dual-recognition of a domain in the protein by the chaperone in facilitating the correct chaperone-substrate organization describes a new function for the TTSS associated chaperone-substrate complexes.
Organizational Affiliation:
Department of Cellular Microbiology, Max-Planck-Institute for Infection Biology, 10117 Berlin, Germany.
