A Key Hydrophobic Patch Identified in an AAA+ Protein Essential for Its In Trans Inhibitory Regulation

Zhang, Nan; Simpson, Timothy; Lawton, Edward; Uzdavinys, Povilas; Joly, Nicolas; Burrows, Patricia; Buck, Martin

Abstract

Bacterial enhancer binding proteins (bEBPs) are a subclass of the AAA + (ATPases Associated with various cellular Activities) protein family. They are responsible for σ54-dependent transcription activation during infection and function under many stressful growth conditions. The majority of bEBPs are regulated in their formation of ring-shaped hexameric self-assemblies via an amino-terminal domain through its phosphorylation or ligand binding. In contrast, the Escherichia coli phage shock protein F (PspF) is negatively regulated in trans by phage shock protein A (PspA). Up to six PspA subunits suppress PspF hexamer action. Here, we present biochemical evidence that PspA engages across the side of a PspF hexameric ring. We identify three key binding determinants located in a surface-exposed 'W56 loop' of PspF, which form a tightly packed hydrophobic cluster, the 'YLW' patch. We demonstrate the profound impact of the PspF W56 loop residues on ATP hydrolysis, the σ54 binding loop 1, and the self-association interface. We infer from single-chain studies that for complete PspF inhibition to occur, more than three PspA subunits need to bind a PspF hexamer with at least two binding to adjacent PspF subunits. By structural modelling, we propose that PspA binds to PspF via its first two helical domains. After PspF binding-induced conformational changes, PspA may then share structural similarities with a bEBP regulatory domain. © 2013 The Authors.

• Journal Article Type: Article
• Acceptance Date: Apr 20, 2023
• Online Publication Date: May 7, 2023
• Publication Date: Aug 9, 2013
• Deposit Date: Jun 13, 2024
• Publicly Available Date: Jun 20, 2024
• Journal: Journal of Molecular Biology
• Print ISSN: 0022-2836
• Electronic ISSN: 1089-8638
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 425
• Issue: 15
• Pages: 2656-2669
• DOI: https://doi.org/10.1016/j.jmb.2013.04.024
• Public URL: https://nottingham-repository.worktribe.com/output/22141322
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0022283613002726?via%3Dihub