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

Arch Biochem Biophys. 2012 Aug 15;524(2):114-22. doi: 10.1016/ Epub 2012 May 17.


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 ∼1 μM) 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 ∼30 μM to over 1 mM with M²⁺. This effect would significantly convert the ATPase activity of PabABCE1 from being independent of cellular energy charge (φ) to being dependent on φ 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / antagonists & inhibitors
  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / metabolism*
  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphate / metabolism
  • Bacterial Proteins / antagonists & inhibitors
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Chelating Agents / pharmacology
  • Edetic Acid / pharmacology
  • Egtazic Acid / pharmacology
  • Hydrolysis
  • Iron*
  • Magnesium / pharmacology*
  • Models, Molecular
  • Protein Structure, Tertiary
  • Pyrococcus abyssi / cytology*
  • Pyrococcus abyssi / enzymology
  • Ribosomes / metabolism*
  • Sulfur*
  • Temperature


  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Chelating Agents
  • Egtazic Acid
  • Adenosine Diphosphate
  • Sulfur
  • Adenosine Triphosphate
  • Edetic Acid
  • Iron
  • Adenosine Triphosphatases
  • Magnesium