Structural characterization of chaperone and substrates from the type three secretion system of bacterium aeromonas hydrophilla

Aeromonas hydrophila is a known opportunistic pathogen that infects fishes and humans. This gram-negative pathogen utilizes the Type Three Secretion System to transport effector proteins into the host cell. Several proteins are essential for the transportation of these effectors, they are the secretion needle subunit, AscF and pore forming translocators, AopB and AopD. Prior to secretion, AopB and AopD are protected by their intra-cellular chaperone AcrH, while AscF is bound to its heterodimeric chaperones AscE-AscG. In this work, we have solved the crystal structure of AscE, and mapped the interaction regions between AscE, AscG and AscF. AscE binds to the N-terminal region of AscG while the N-terminus of AscF binds to the C-terminus of AscG and stabilizes the latter. Structural characterization was also performed on the chaperone-translocator complexes formed between AcrH with AopB and/or AopD. We have mapped the binding region between chaperone AcrH and the translocators AopB and AopD to be the trans-membrane region of both translocators and the amphipathic helix region of AopD. We have also successfully shown complex formation between all three proteins AcrH-AopB-AopD.

Author dc:creator

• TAN YIH WAN, YVONNE

• Aeromonas hydrophila, Structure, chaperone, translocators, type III secretion system, chaperone binding region