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Title: Structural and biophysical characterisation of the translocation and assembly module (TAM) complex from Escherichia coli
Author: Josts, Inokentijs
ISNI:       0000 0004 5348 1223
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 2014
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Bacterial proteins destined to function extracellularly must efficiently cross two layers of membrane covering the cells. To do so, numerous transporter systems are employed to ensure the delivery of these proteins to their final destination in their fully functional state. Autotransporters are outer membrane bound proteins that act in the extracellular milleau of the cells and act as virulence factors mediating contact with the host and the manipulation of host defence. The translocation assembly module (TAM complex) is a cell envelope spanning complex produced by Gram-negative bacteria that facilitates efficient secretion of autotransporters across the outer membrane. This complex consists of the outer membrane protein TamA, a member of the Omp85 superfamily of proteins, which consists of an integral membrane β-barrel domain and three soluble periplasmic polypeptide transport (POTRA) domains and the large inner membrane anchored protein TamB. This work examines the interactions between TamA and TamB which are mediated through interaction of the central polypeptide transport domain of TamA and the C-terminal region of the DUF490 domain of TamB. In addition, it is also demonstrated that TamB forms a complex with the unfolded passenger domain of the substrate autotransporter Ag43 and that the TamA and Ag43 binding epitopes of TamB are overlapping but not identical. These data suggest that TamB acts as a chaperone, delivering autotransporter passenger domains to the TamA POTRA domains, which interact transiently with the Ag43 passenger domain. These transient interactions presumably act to guide the unfolded polypeptide into the TamA barrel for efficient secretion across the outer membrane.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology