AI Article Synopsis

  • Signaling nucleotides play a crucial role in helping bacteria, like Staphylococcus aureus, respond to environmental changes, with the PII-like protein PstA being identified as a key player by binding cyclic diadenylate monophosphate (c-di-AMP).
  • Research revealed that PstA forms a trimeric structure and belongs to a new protein family, displaying unique characteristics compared to classical PII proteins associated with nitrogen metabolism.
  • The analysis of crystal structures showed three distinct c-di-AMP-binding sites on PstA, leading to insights on conformational changes that model the protein’s function in signal transduction.

Article Abstract

Signaling nucleotides are integral parts of signal transduction systems allowing bacteria to cope with and rapidly respond to changes in the environment. The Staphylococcus aureus PII-like signal transduction protein PstA was recently identified as a cyclic diadenylate monophosphate (c-di-AMP)-binding protein. Here, we present the crystal structures of the apo- and c-di-AMP-bound PstA protein, which is trimeric in solution as well as in the crystals. The structures combined with detailed bioinformatics analysis revealed that the protein belongs to a new family of proteins with a similar core fold but with distinct features to classical PII proteins, which usually function in nitrogen metabolism pathways in bacteria. The complex structure revealed three identical c-di-AMP-binding sites per trimer with each binding site at a monomer-monomer interface. Although distinctly different from other cyclic-di-nucleotide-binding sites, as the half-binding sites are not symmetrical, the complex structure also highlighted common features for c-di-AMP-binding sites. A comparison between the apo and complex structures revealed a series of conformational changes that result in the ordering of two anti-parallel β-strands that protrude from each monomer and allowed us to propose a mechanism on how the PstA protein functions as a signaling transduction protein.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4316997PMC
http://dx.doi.org/10.1074/jbc.M114.621789DOI Listing

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