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Investigation of the Mechanism and Structure of the Cage-like Complex formed by the Escherichia coli Inducible Lysine Decarboxylase LdcI and the MoxR AAA+ ATPase RavA

The gram-negative bacteria Escherichia coli, a neutralophile, is remarkable in its defenses against acid stress. Of interest to our laboratory is the inducible lysine decarboxylase (LdcI) system, an acid resistance system which renders acid resistance to E. coli in mild acid stress
(~pH 5). It was found that this enzyme forms an extremely large (~3.3 MDa) and tight complex (Kd ~ 0.56 μM) with a MoxR AAA+ ATPase named Regulatory ATPase Variant A (RavA). The cryo-EM structure at 14 Å was determined. Through size-exclusion chromatography (SEC) experiments, the binding sites on both LdcI and RavA have been determined. It is proposed that
the complex can form through both charged and hydrophobic interactions. In the course of these studies, unexpected observations led to the characterization of the LARA domain of RavA as an amyloid protein under in vitro conditions. The physiological significance of this observation is still under investigation.

Identiferoai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43098
Date05 December 2013
CreatorsLiu, Kaiyin
ContributorsHoury, Walid A.
Source SetsUniversity of Toronto
Languageen_ca
Detected LanguageEnglish
TypeThesis

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