title: Insights into the function and structural flexibility of the periplasmic molecular chaperone SurA.
abstract: SurA is the primary periplasmic molecular chaperone that facilitates the folding and assembling of outer membrane proteins (OMPs) in Gram-negative bacteria. Deletion of the surA gene in Escherichia coli leads to a decrease in outer membrane density and an increase in bacterial drug susceptibility. Here, we conducted mutational studies on SurA to identify residues that are critical for function. One mutant, SurA(V37G), significantly reduced the activity of SurA. Further characterization indicated that SurA(V37G) was structurally similar to, but less stable than, the wild-type protein. The loss of activity in SurA(V37G) could be restored through the introduction of a pair of Cys residues and the subsequent formation of a disulfide bond. Inspired by this success, we created three additional SurA constructs, each containing a disulfide bond at different regions of the protein between two rigid secondary structural elements. The formation of disulfide bond in these mutants has no observable detrimental effect on protein activity, indicating that SurA does not undergo large-scale conformational change while performing its function.
authors.affiliation: Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhong
authors.forename: Brent
authors.initials: B
authors.lastname: Ferrell
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.forename: Qian
authors.initials: Q
authors.lastname: Chai
authors.forename: Yinan
authors.initials: Y
authors.lastname: Wei
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D055786:Gene Knockout Techniques; D007612:Kanamycin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation; D009675:Novobiocin / Q000494:pharmacology; D019696:Peptidylprolyl Isomerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019897:Periplasm; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D050505:Mutant Proteins; D009675:Novobiocin; D007612:Kanamycin; D000667:Ampicillin; C490900:SurA protein, E coli; D019696:Peptidylprolyl Isomerase