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

    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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