Download MendeleyDisulfide isomerase activity of the dynamic, trimericProteus mirabilisScsC protein is primed by the tandem immunoglobulin-fold domain of ScsB.
Furlong, E.J., Choudhury, H.G., Kurth, F., Duff, A.P., Whitten, A.E., Martin, J.L.(2018) J Biological Chem 293: 5793-5805
- PubMed: 29491145
- DOI: https://doi.org/10.1074/jbc.RA118.001860
- Primary Citation of Related Structures:
6C29 - PubMed Abstract:
Correct disulfide bond formation is essential for proper folding of many proteins, including bacterial virulence factors. The suppressor of copper sensitivity (Scs) proteins have roles in dithiol/disulfide interchange and the bacterial response to copper stress. Encoded in a four-gene cassette (ScsABCD) present in many Gram-negative bacteria, the Scs proteins are enigmatic and poorly characterized. Here, we show that the periplasmic α-domain of the membrane protein ScsB in the Gram-negative bacterium Proteus mirabilis forms a redox relay with the soluble periplasmic protein PmScsC. We also found that the periplasmic α-domain is sufficient to activate the disulfide isomerase activity of PmScsC. The crystal structure of PmScsBα at a resolution of 1.54 Å revealed that it comprises two structurally similar immunoglobulin-like folds, one of which includes a putative redox-active site with the sequence C XXX C. We confirmed the importance of these cysteine residues for PmScsBα function, and in addition, we engineered cysteine variants that produced a stable complex between PmScsC and PmScsBα. Using small-angle X-ray and neutron scattering analyses with contrast variation, we determined a low-resolution structure of the PmScsC-PmScsBα complex. The structural model of this complex suggested that PmScsBα uses both of its immunoglobulin-like folds to interact with PmScsC and revealed that the highly dynamic PmScsC becomes ordered upon PmScsBα binding. These findings add to our understanding of the poorly characterized Scs proteins.
- From the Institute for Molecular Bioscience, University of Queensland, St, Lucia, Queensland 4072, Australia.
Organizational Affiliation:
