4whe
Crystal structure of E. coli phage shock protein A (PspA 1-144)
Structural highlights
FunctionPSPA_ECOLI The phage shock protein (psp) operon (pspABCDE) may play a significant role in the competition for survival under nutrient- or energy-limited conditions. PspA negatively regulates expression of the pspABCDE promoter and of pspG through negative regulation of the psp-specific transcriptional activator PspF. Is also required for membrane integrity, efficient translocation and maintenance of the proton motive force.[1] [2] [3] [4] [5] Publication Abstract from PubMedPhage 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 sigma54 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 sigma54 -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 PspF in 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 physiological tasks via coiled-coil domains. The PspF-binding domain PspA and the PspA.F complex - New insights into the coiled-coil dependent regulation of AAA+ proteins.,Osadnik H, Schopfel M, Heidrich E, Mehner D, Lilie H, Parthier C, Risselada HJ, Grubmuller H, Stubbs MT, Bruser T Mol Microbiol. 2015 Aug 3. doi: 10.1111/mmi.13154. PMID:26235546[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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