Structural insight into serine protease Rv3671c that Protects M. tuberculosis from oxidative and acidic stress.
Rv3671c, a putative serine protease, is crucial for persistence of Mycobacterium tuberculosis in the hostile environment of the phagosome. We show that Rv3671c is required for M. tuberculosis resistance to oxidative stress in addition to its role in protection from acidification. Structural and biochemical analyses demonstrate that the periplasmic domain of Rv3671c is a functional serine protease of the chymotrypsin family and, remarkably, that its activity increases on oxidation. High-resolution crystal structures of this protease in an active strained state and in an inactive relaxed state reveal that a solvent-exposed disulfide bond controls the protease activity by constraining two distant regions of Rv3671c and stabilizing it in the catalytically active conformation. In vitro biochemical studies confirm that activation of the protease in an oxidative environment is dependent on this reversible disulfide bond. These results suggest that the disulfide bond modulates activity of Rv3671c depending on the oxidative environment in vivo.
Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
Tapan
T
Biswas
Jennifer
J
Small
Omar
O
Vandal
Toshiko
T
Odaira
Haiteng
H
Deng
Sabine
S
Ehrt
Oleg V
OV
Tsodikov
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D003460:Crystallization; D003545:Cysteine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D057057:Serine Proteases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014961:X-Ray Diffraction
D001426:Bacterial Proteins; D004220:Disulfides; D057057:Serine Proteases; D003545:Cysteine