SilE is an intrinsically disordered periplasmic “molecular sponge” involved in bacterial silver resistance |
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| Authors: | Karishma R Asiani Huw Williams Louise Bird Matthew Jenner Mark S Searle Jon L Hobman David J Scott Panos Soultanas |
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| Institution: | 1. School of Biosciences, University of Nottingham, Sutton, Bonington, United Kingdom;2. Centre for Biomolecular Sciences, School of Chemistry, University Park, University of Nottingham, Nottingham, United Kingdom;3. Oxford Protein Production Factory, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom;4. Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, United Kingdom;5. ISIS Neutron and Muon Source and Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom |
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| Abstract: | Ag+ resistance was initially found on the Salmonella enetrica serovar Typhimurium multi‐resistance plasmid pMG101 from burns patients in 1975. The putative model of Ag+ resistance, encoded by the sil operon from pMG101, involves export of Ag+ via an ATPase (SilP), an effluxer complex (SilCFBA) and a periplasmic chaperon of Ag+ (SilE). SilE is predicted to be intrinsically disordered. We tested this hypothesis using structural and biophysical studies and show that SilE is an intrinsically disordered protein in its free apo‐form but folds to a compact structure upon optimal binding to six Ag+ ions in its holo‐form. Sequence analyses and site‐directed mutagenesis established the importance of histidine and methionine containing motifs for Ag+‐binding, and identified a nucleation core that initiates Ag+‐mediated folding of SilE. We conclude that SilE is a molecular sponge for absorbing metal ions. |
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