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Type III secretion chaperones: a molecular toolkit for all occasions
Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). (Francis)
2010 (English)In: Handbook of molecular chaperones: roles, structures and mechanisms / [ed] Piero Durante and Leandro Colucci, New York: Nova Science Publishers , 2010, 1, 79-148 p.Chapter in book (Refereed)
Abstract [en]

Common to many bacteria is the ability to establish a symbiotic relationship or to evade innate immune responses of an animal, plant, fish or insect host. Most often this capacity is mediated by a type III secretion system (T3SS). The function of these complex molecular machines is likened to a syringe-needle injection device that is dedicated to the translocation of effector proteins directly into target eukaryotic cells. Each translocated effector tends to possess a distinct enzymatic activity that aids in subverting host cell signaling for the benefit of the bacterium. Their translocation requires another class of secreted protein – the translocator – which form pores in the target eukaryotic cell plasma membrane through which the effectors may transit to gain entry into the cell interior. Most often, each secreted substrate requires a dedicated small, non-secreted cytoplasmic chaperone for their efficient secretion. Unlike traditional molecular chaperones, these specialized type III chaperones do not assist in protein folding and are not energized by ATP. Controversy still surrounds their primary role; as bodyguards to prevent premature aggregation or as pilots to direct substrate secretion through the correct T3SS. The later is supported by recent evidence that these chaperones can dock directly to the cytoplasmic face of the T3S machinery, possibly serving as a recognition motif for substrate secretion. Added to this functional complexity is their important contribution to system regulation, which can ultimately confer temporal order to substrate secretion. Moreover, some chaperones display a bewildering propensity to interact with several additional T3S-associated proteins – the relevance of which remains uncertain. Structural data has now appeared for several important type III chaperones, either alone or in complex with their cognate substrate. This is proving a fillip in our attempts to understand the mercurial ways in which these versatile proteins operate in nature. It is hoped that this article will provide information on type III chaperone function, as well as highlighting key recent advances in the field. May it also be a testament to the value of continued intense effort in unravelling the mysteries of type III chaperone biology.

Place, publisher, year, edition, pages
New York: Nova Science Publishers , 2010, 1. 79-148 p.
Cell Biology Research Progress
National Category
Microbiology in the medical area
Research subject
Infectious Diseases
URN: urn:nbn:se:umu:diva-41865ISBN: 978-1-60876-366-5 (print)OAI: diva2:407980
Available from: 2011-04-28 Created: 2011-04-01 Last updated: 2011-04-28Bibliographically approved

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Francis, Matthew S
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