ATPase Site Architecture Is Required for Self-Assembly and Remodeling Activity of a Hexameric AAA+ Transcriptional Activator

Nicolas Joly,Nan Zhang,Martin Buck

doi:10.1016/j.molcel.2012.06.012

Abstract

SummaryAAA+ proteins (ATPases associated with various cellular activities) are oligomeric ATPases that use ATP hydrolysis to remodel their substrates. By similarity with GTPases, a dynamic organization of the nucleotide-binding pockets between ATPase protomers is proposed to regulate functionality. Using the transcription activator PspF as an AAA+ model, we investigated contributions of conserved residues for roles in ATP hydrolysis and intersubunit communication. We determined the R-finger residue and revealed that it resides in a conserved “R-hand” motif (RxDxxxR) needed for its “trans-acting” activity. Further, a divergent Walker A glutamic acid residue acts synergistically with a tyrosine residue to function in ADP-dependent subunit-subunit coordination, forming the “ADP-switch” motif. Another glutamic acid controls hexamer formation in the presence of nucleotides. Together, these results lead to a “residue-nucleotide” interaction map upon which to base AAA+ core regulation.

Highlights

AAA+ proteins (ATPases associated with various cellular activities) are present in each kingdom of life
By analogy with GTPases for which efficient GTP hydrolysis depends on the presence of a trans arginine residue (Ahmadian et al, 1997; Scheffzek et al, 1997), putative conserved trans-acting arginine residues have been identified in the AAA+ ATPases in the second region of homology (SRH) domain
The Walker A Motif Is Involved in an Unexpected trans Subunit Communication Pathway In PspF the Walker A motif, essential for nucleotide binding, is GxxxxGKEL (Walker et al, 1982)

Summary

SUMMARY

AAA+ proteins (ATPases associated with various cellular activities) are oligomeric ATPases that use ATP hydrolysis to remodel their substrates. Using the transcription activator PspF as an AAA+ model, we investigated contributions of conserved residues for roles in ATP hydrolysis and intersubunit communication. A divergent Walker A glutamic acid residue acts synergistically with a tyrosine residue to function in ADP-dependent subunit-subunit coordination, forming the ‘‘ADP-switch’’ motif. Another glutamic acid controls hexamer formation in the presence of nucleotides. Together, these results lead to a ‘‘residue-nucleotide’’ interaction map upon which to base AAA+ core regulation

INTRODUCTION

RESULTS

DISCUSSION

EXPERIMENTAL PROCEDURES