Characterization and Mechanism of Action of a Reactivating Factor for Adenosylcobalamin-dependent Glycerol Dehydratase

66Citations
Citations of this article
49Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

Adenosylcobalamin-dependent glycerol dehydratase undergoes mechanism-based inactivation by its physiological substrate glycerol. We identified two genes (gdrAB) of Klebsiella pneumoniae for a glycerol dehydratase-reactivating factor (Tobimatsu, T., Kajiura, H., Yunoki, M., Azuma, M., and Toraya, T. (1999) J. Bacteriol. 181, 4110-4113). Recombinant GdrA and GdrB proteins formed a tight complex of (GdrA)2(GdrB)2, which is a putative reactivating factor. The purified factor reactivated the glycerol-inactivated and O2-inactivated glycerol dehydratases as well as activated the enzyme-cyanocobalamin complex in vitro in the presence of ATP, Mg2+, and adenosylcobalamin. The factor mediated the exchange of the enzyme-bound, adenine-lacking cobalamins for free, adenine-containing cobalamins in the presence of ATP and Mg2+ through intermediate formation of apoenzyme. The factor showed extremely low ATP-hydrolyzing activity and formed a tight complex with apoenzyme in the presence of ADP. Incubation of the enzyme-cyanocobalamin complex with the reactivating factor in the presence of ADP brought about release of the enzyme-bound cobalamin. The resulting tight inactive complex of apoenzyme with the factor dissociated upon incubation with ATP, forming functional apoenzyme and a low affinity form of factor. Thus, it was established that the reactivation of the inactivated holoenzymes takes place in two steps: ADP-dependent cobalamin release and ATP-dependent dissociation of the apoenzyme-factor complex. We propose that the glycerol dehydratase-reactivating factor is a molecular chaperone that participates in reactivation of the inactivated enzymes.

Cite

CITATION STYLE

APA

Kajiura, H., Mori, K., Tobimatsu, T., & Toraya, T. (2001). Characterization and Mechanism of Action of a Reactivating Factor for Adenosylcobalamin-dependent Glycerol Dehydratase. Journal of Biological Chemistry, 276(39), 36514–36519. https://doi.org/10.1074/jbc.M105182200

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free