Mechanistic and structural insights into the proteolytic activation of Vibrio cholerae MARTX toxin

• Published in: Nature chemical biology Vol. 5; no. 7; pp. 469 - 478
• Main Authors: Shen, Aimee, Bogyo, Matthew, Lupardus, Patrick J, Albrow, Victoria E, Guzzetta, Andrew, Powers, James C, Garcia, K Christopher
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.07.2009; Nature Publishing Group
• Subjects: Allosteric Regulation; Amino Acid Sequence; Antitoxins; Bacteria; Biochemical Engineering; Biochemistry; Bioorganic Chemistry; Blotting, Western; Catalytic Domain; Cell Biology; Cellular biology; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Cholera Toxin - chemistry; Cholera Toxin - metabolism; Crystallography, X-Ray; Cysteine Proteases - metabolism; Cysteine Proteinase Inhibitors - pharmacology; Enzyme Activation - drug effects; Inhibitors; Models, Molecular; Molecular biology; Molecular Sequence Data; Pathogens; Proteases; Protein Binding; Protein Structure, Secondary; Sequence Alignment; Spectroscopy, Fourier Transform Infrared; Substrate Specificity; Substrates; Toxins; Vibrio cholerae; Vibrio cholerae - drug effects; Vibrio cholerae - enzymology; Vibrio cholerae - metabolism
• ISSN: 1552-4450; 1552-4469
• DOI: 10.1038/nchembio.178

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 MARTX Vc enhances effector domain function. We also identify the first small-molecule inhibitors of this protease domain and present the 2.35-Å 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.