Structural and biochemical characterization of the oxidoreductase NmDsbA3 from Neisseria meningitidis.
DsbA is an enzyme found in the periplasm of Gram-negative bacteria that catalyzes the formation of disulfide bonds in a diverse array of protein substrates, many of which are involved in bacterial pathogenesis. Although most bacteria possess only a single essential DsbA, Neisseria meningitidis is unusual in that it possesses three DsbAs, although the reason for this additional redundancy is unclear. Two of these N. meningitidis enzymes (NmDsbA1 and NmDsbA2) play an important role in meningococcal attachment to human epithelial cells, whereas NmDsbA3 is considered to have a narrow substrate repertoire. To begin to address the role of DsbAs in the pathogenesis of N. meningitidis, we have determined the structure of NmDsbA3 to 2.3-A resolution. Although the sequence identity between NmDsbA3 and other DsbAs is low, the NmDsbA3 structure adopted a DsbA-like fold. Consistent with this finding, we demonstrated that NmDsbA3 acts as a thiol-disulfide oxidoreductase in vitro and is reoxidized by Escherichia coli DsbB (EcDsbB). However, pronounced differences in the structures between DsbA3 and EcDsbA, which are clustered around the active site of the enzyme, suggested a structural basis for the unusual substrate specificity that is observed for NmDsbA3.
Vivian
Julian P
JP
The Protein Crystallography Unit, ARC Centre of Excellence in Structural and Functional Microbial Genomics, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia.
Scoullar
Jessica
J
Robertson
Amy L
AL
Bottomley
Stephen P
SP
Horne
James
J
Chin
Yanni
Y
Wielens
Jerome
J
Thompson
Philip E
PE
Velkov
Tony
T
Piek
Susannah
S
Byres
Emma
E
Beddoe
Travis
T
Wilce
Matthew C J
MC
Kahler
Charlene M
CM
Rossjohn
Jamie
J
Scanlon
Martin J
MJ
D001426:Bacterial Proteins / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D004229:Dithiothreitol / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry; D007328:Insulin / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry; D009345:Neisseria meningitidis / Q000737:chemistry / Q000201:enzymology*; D010088:Oxidoreductases / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D011487:Protein Conformation; D011490:Protein Disulfide Reductase (Glutathione) / Q000737:chemistry* / Q000502:physiology*; D019704:Protein Disulfide-Isomerases / Q000737:chemistry; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D013379:Substrate Specificity
D001426:Bacterial Proteins; C079503:DsbB protein, Bacteria; D029968:Escherichia coli Proteins; D007328:Insulin; D008565:Membrane Proteins; D011994:Recombinant Proteins; D004247:DNA; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); D019704:Protein Disulfide-Isomerases; C526648:dsbA protein, E coli; D010100:Oxygen; D004229:Dithiothreitol