Title

Regulation of the ATPase activity of ABCE1 from Pyrococcus abyssi by Fe-S cluster status and Mg2+: Implication for ribosomal function

Authors

Authors

L. M. Sims;R. Y. Igarashi

Comments

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Abbreviated Journal Title

Arch. Biochem. Biophys.

Keywords

ABCE1; PabABCE1; Ribosome; ATPase; Fe-S cluster; RNASE-L INHIBITOR; SUB-MITOCHONDRIAL PARTICLES; 2-5A/RNASE L PATHWAY; X-RAY-STRUCTURE; ADENOSINE-TRIPHOSPHATASE; PROTEIN-SYNTHESIS; HUMAN; RAD51; ADP; MAGNESIUM; BINDING; Biochemistry & Molecular Biology; Biophysics

Abstract

Ribosomal function is dependent on multiple proteins. The ABCE1 ATPase, a unique ABC superfamily member that bears two Fe4S4 clusters, is crucial for ribosomal biogenesis and recycling. Here, the ATPase activity of the Pyrococcus abyssi ABCE1 (PabABCE1) was studied using both apo- (without reconstituted Fe-S clusters) and holo- (with full complement of Fe-S clusters reconstituted post-purification) forms, and is shown to be jointly regulated by the status of Fe-S clusters and Mg2+. Typically ATPases require Mg2+, as is true for PabABCE1, but Mg2+ also acts as a negative allosteric effector that modulates ATP affinity of PabABCE1. Physiological [Mg2+] inhibits the PabABCE1 ATPase (K-i of similar to 1 mu M) for both apo- and holo-PabABCE1. comparative kinetic analysis of Mg2+ inhibition shows differences in degree of allosteric regulation between the apo- and holo-PabABCE1 where the apparent ATP K-m of apo-PabABCE1 increases >30-fold from similar to 30 mu M to over 1 mM with Mg2+. This effect would significantly convert the ATPase activity of PabABCE1 from being independent of cellular energy charge (phi) to being dependent on phi with cellular [Mg2+]. These findings uncover intricate overlapping effects by both [Mg2+] and the status of Fe-S clusters that regulate ABCE1's ATPase activity with implications to ribosomal function. (C) 2012 Elsevier Inc. All rights reserved.

Journal Title

Archives of Biochemistry and Biophysics

Volume

524

Issue/Number

2

Publication Date

1-1-2012

Document Type

Article

Language

English

First Page

114

Last Page

122

WOS Identifier

WOS:000306622000005

ISSN

0003-9861

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