期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 425, 期 15, 页码 2656-2669出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2013.04.024
关键词
AAA(+) proteins; PspF; PspA; enhancer binding protein; sigma 54
资金
- Biotechnology and Biological Sciences Research Council [BB/J002828/1, BB/G001278/1]
- Wellcome Trust [WT093044MA]
- Biotechnology and Biological Sciences Research Council [BB/G001278/1, BB/J002828/1] Funding Source: researchfish
- BBSRC [BB/G001278/1, BB/J002828/1] Funding Source: UKRI
Bacterial enhancer binding proteins (bEBPs) are a subclass of the AAA(+) (ATPases Associated with various cellular Activities) protein family. They are responsible for sigma(54)-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 sigma(54) 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. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
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