Papers In Press, published online ahead of print November 21, 2005
J. Biol. Chem, 10.1074/jbc.M511172200
Submitted on October 13, 2005
Accepted on November 21, 2005
Formation of a distinctive complex between the inducible bacterial lysine decarboxylase and a novel AAA+ ATPase
Jamie Snider, Irina Gutsche, Michelle Lin, Sabulal Baby, Brian Cox, Gareth Butland, Jack Greenblatt, Andrew Emili, and Walid A. Houry
Biochemistry Dept., University of Toronto, Toronto, Ontario M5S 1A8
Corresponding Author: walid.houry{at}utoronto.ca
AAA+ ATPases are ubiquitous proteins that employ the energy obtained from ATP hydrolysis to remodel proteins, DNA, or RNA. The MoxR family of AAA+ proteins is widespread throughout bacteria and archaea, but is largely uncharacterized. Limited work with specific members has suggested a potential role as molecular chaperones involved in the assembly of protein complexes. As part of an effort aimed at determining the function of novel AAA+ chaperones in Escherichia coli, we report the characterization of a representative member of the MoxR family, YieN, which we have renamed RavA (Regulatory ATPase Variant A). We show that the ravA gene exists on an operon with another gene encoding a protein, YieM, of unknown function containing a Von Willebrand Factor Type A (VWA) domain. RavA expression is under the control of the S transcription factor, and its levels increase towards late log/early stationary phase, consistent with its possible role as a general stress response protein. RavA functions as an ATPase and forms hexameric oligomers. Importantly, we demonstrate that RavA interacts strongly with inducible lysine decarboxylase (LdcI or CadA) forming a large cage-like structure consisting of two LdcI decamers linked by a maximum of five RavA oligomers. Surprisingly, the activity of LdcI does not appear to be affected by binding to RavA in a number of in vitro and in vivo assays, however, complex formation results in the stimulation of RavA ATPase activity. Data obtained suggest that the RavA-LdcI interaction may be important for the regulation of RavA activity against its targets.