PspF-binding domain PspA_1-144 and the PspA·F complex

New insights into the coiled-coil-dependent regulation of AAA+ proteins

authored by

Hendrik Osadnik, Michael Schöpfel, Eyleen Heidrich, Denise Mehner, Hauke Lilie, Christoph Parthier, H. Jelger Risselada, Helmut Grubmüller, Milton T. Stubbs, Thomas Brüser

Abstract

Phage shock protein A (PspA) belongs to the highy conserved PspA/IM30 family and is a key component of the stress inducible Psp system in Escherichia coli. One of its central roles is the regulatory interaction with the transcriptional activator of this system, the σ⁵⁴ enhancer-binding protein PspF, a member of the AAA+ protein family. The PspA/F regulatory system has been intensively studied and serves as a paradigm for AAA+ enzyme regulation by trans-acting factors. However, the molecular mechanism of how exactly PspA controls the activity of PspF and hence σ⁵⁴-dependent expression of the psp genes is still unclear. To approach this question, we identified the minimal PspF-interacting domain of PspA, solved its structure, determined its affinity to PspF and the dissociation kinetics, identified residues that are potentially important for PspF regulation and analyzed effects of their mutation on PspFin vivo and in vitro. Our data indicate that several characteristics of AAA+ regulation in the PspA·F complex resemble those of the AAA+ unfoldase ClpB, with both proteins being regulated by a structurally highly conserved coiled-coil domain. The convergent evolution of both regulatory domains points to a general mechanism to control AAA+ activity for divergent physiologic tasks via coiled-coil domains. PspA is the regulator of the AAA+ protein PspF, the transcriptional activator of the psp system in Escherichia coli. The crystal structure of the PspF-binding domain of PspA indicates a conserved architecture of PspA-like proteins, and data from mutational analyses suggest that PspF regulation might be more complex than previously thought. Similarities to the M-domain of the AAA+ disaggregase ClpB point to convergently evolved characteristics in AAA+ regulation.

Organisation(s)

Institute of Microbiology

External Organisation(s)

University of California at San Francisco
Martin Luther University Halle-Wittenberg
Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute)
Leibniz Institute of Surface Engineering (IOM)

Type

Article

Journal

Molecular Microbiology

Volume

98

Pages

743-759

No. of pages

17

ISSN

0950-382X

Publication date

11.2015

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Microbiology, Molecular Biology

Electronic version(s)

https://doi.org/10.1111/mmi.13154 (Access: Open)