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  • The multidrug resistance IncA/C transferable plasmid encodes a novel domain-swapped dimeric protein-disulfide isomerase.

The multidrug resistance IncA/C transferable plasmid encodes a novel domain-swapped dimeric protein-disulfide isomerase.

The Journal of biological chemistry (2013-12-07)
Lakshmanane Premkumar, Fabian Kurth, Simon Neyer, Mark A Schembri, Jennifer L Martin
ZUSAMMENFASSUNG

The multidrug resistance-encoding IncA/C conjugative plasmids disseminate antibiotic resistance genes among clinically relevant enteric bacteria. A plasmid-encoded disulfide isomerase is associated with conjugation. Sequence analysis of several IncA/C plasmids and IncA/C-related integrative and conjugative elements (ICE) from commensal and pathogenic bacteria identified a conserved DsbC/DsbG homolog (DsbP). The crystal structure of DsbP reveals an N-terminal domain, a linker region, and a C-terminal catalytic domain. A DsbP homodimer is formed through domain swapping of two DsbP N-terminal domains. The catalytic domain incorporates a thioredoxin-fold with characteristic CXXC and cis-Pro motifs. Overall, the structure and redox properties of DsbP diverge from the Escherichia coli DsbC and DsbG disulfide isomerases. Specifically, the V-shaped dimer of DsbP is inverted compared with EcDsbC and EcDsbG. In addition, the redox potential of DsbP (-161 mV) is more reducing than EcDsbC (-130 mV) and EcDsbG (-126 mV). Other catalytic properties of DsbP more closely resemble those of EcDsbG than EcDsbC. These catalytic differences are in part a consequence of the unusual active site motif of DsbP (CAVC); substitution to the EcDsbC-like (CGYC) motif converts the catalytic properties to those of EcDsbC. Structural comparison of the 12 independent subunit structures of DsbP that we determined revealed that conformational changes in the linker region contribute to mobility of the catalytic domain, providing mechanistic insight into DsbP function. In summary, our data reveal that the conserved plasmid-encoded DsbP protein is a bona fide disulfide isomerase and suggest that a dedicated oxidative folding enzyme is important for conjugative plasmid transfer.

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Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, Type I-A, powder, ≥60% RNase A basis (SDS-PAGE), ≥50 Kunitz units/mg protein
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, for molecular biology, ≥70 Kunitz units/mg protein, lyophilized
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, Type III-A, ≥85% RNase A basis (SDS-PAGE), 85-140 Kunitz units/mg protein
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, (Solution of 50% glycerol, 10mM Tris-HCL pH 8.0)
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, Type I-AS, 50-100 Kunitz units/mg protein
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, Type XII-A, ≥90% (SDS-PAGE), 75-125 Kunitz units/mg protein
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, Type II-A, ≥60% (SDS-PAGE), >= 60 Kunitz units/mg protein
Sigma-Aldrich
Ribonuklease B aus Rinderpankreas, BioReagent, ≥50 Kunitz units/mg protein, ≥80% (SDS-PAGE)
Sigma-Aldrich
Protein-Disulfid-Isomerase aus Rinderleber, ≥100 units/mg protein, lyophilized powder
Sigma-Aldrich
Ribonuklease A aus Rinderpankreas, Type X-A, ≥90% (SDS-PAGE), ≥70 Kunitz units/mg protein
Sigma-Aldrich
Ribonuclease A-agarose, ammonium sulfate suspension, 400-1,000 units/g agarose (One ml gel will yield 12-30 units)