Mechanistic and structural insights into the proteolytic  activation of Vibrio cholerae MARTX toxin.
MARTX toxins modulate the virulence of a number of Gram-negative Vibrio species. This family of toxins is defined by the presence of a cysteine protease domain (CPD), which proteolytically activates the Vibrio cholerae MARTX toxin. Although recent structural studies of the CPD have uncovered a new allosteric activation mechanism, the mechanism of CPD substrate recognition or toxin processing is unknown. Here we show that interdomain cleavage of MARTXVc enhances effector domain function. We also identify the first small-molecule inhibitors of this protease domain and present the 2.35-A structure of the CPD bound to one of these inhibitors. This structure, coupled with biochemical and mutational studies of the toxin, reveals the molecular basis of CPD substrate specificity and underscores the evolutionary relationship between the CPD and the clan CD caspase proteases. These studies are likely to prove valuable for devising new antitoxin strategies for a number of bacterial pathogens.
Shen
Aimee
A
Department of Pathology, and Howard Hughes Medical Institute, Stanford School of Medicine, Stanford,California, USA.
Lupardus
Patrick J
PJ
Albrow
Victoria E
VE
Guzzetta
Andrew
A
Powers
James C
JC
Garcia
K Christopher
KC
Bogyo
Matthew
M
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D015153:Blotting, Western; D020134:Catalytic Domain; D002772:Cholera Toxin / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D057056:Cysteine Proteases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017550:Spectroscopy, Fourier Transform Infrared; D013379:Substrate Specificity; D014734:Vibrio cholerae / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
D015853:Cysteine Proteinase Inhibitors; D002772:Cholera Toxin; D057056:Cysteine Proteases