Structure of CcmG/DsbE at 1.14 A resolution: high-fidelity reducing activity in an indiscriminately oxidizing environment.
CcmG is unlike other periplasmic thioredoxin (TRX)-like proteins in that it has a specific reducing activity in an oxidizing environment and a high fidelity of interaction. These two unusual properties are required for its role in c-type cytochrome maturation. The crystal structure of CcmG reveals a modified TRX fold with an unusually acidic active site and a groove formed from two inserts in the fold. Deletion of one of the groove-forming inserts disrupts c-type cytochrome formation. Two unique structural features of CcmG-an acidic active site and an adjacent groove-appear to be necessary to convert an indiscriminately binding scaffold, the TRX fold, into a highly specific redox protein.
Centre for Drug Design and Development and Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, Brisbane QLD 4072, Australia.
Melissa A
MA
Edeling
Luke W
LW
Guddat
Renata A
RA
Fabianek
Linda
L
Thöny-Meyer
Jennifer L
JL
Martin
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D020369:Bradyrhizobium / Q000737:chemistry; D018360:Crystallography, X-Ray; D003574:Cytochrome c Group / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D033903:Periplasmic Proteins / Q000737:chemistry*; D017510:Protein Folding; D016415:Sequence Alignment; D013879:Thioredoxins / Q000737:chemistry
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D033903:Periplasmic Proteins; D013879:Thioredoxins; D010088:Oxidoreductases; C077913:periplasmic protein disulfide oxidoreductase