N-Terminal Protease of Pestiviruses: Identification of Putative Catalytic Residues by Site-Directed Mutagenesis
AUTOR(ES)
Rümenapf, Tillmann
FONTE
American Society for Microbiology
RESUMO
Pestiviruses are the only members of the Flaviviridae that encode a nonstructural protease at the N terminus of their polyproteins. This N-terminal protease (Npro) cleaves itself off of the nascent polyprotein autocatalytically and thereby generates the N terminus of the adjacent viral capsid protein C. In previous reports, sequence similarities between Npro and the catalytic residues of papain-like cysteine proteases were put forward. To test this hypothesis, substitutions of cysteine and histidine residues within Npro were carried out by site-directed mutagenesis. Translation of the mutagenized Npro-C proteins in cell-free lysates confirmed that only the predicted Cys69 was an essential amino acid for proteolysis, not His130. Further essential residues were identified with His49 and Glu22. While it remains speculative whether Glu22-His49-Cys69 actually build a catalytic triad, these results invalidate the assumption that Npro is a papain-like cysteine protease.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=109561Documentos Relacionados
- Fine Mapping of the N-Terminal Cytotoxicity Region of Clostridium perfringens Enterotoxin by Site-Directed Mutagenesis
- Role of myristoylation of poliovirus capsid protein VP4 as determined by site-directed mutagenesis of its N-terminal sequence.
- Identification of active-site residues in protease 3C of hepatitis A virus by site-directed mutagenesis.
- Analysis of the role of cysteine residues in isopenicillin N synthetase activity by site-directed mutagenesis.
- Site-directed mutagenesis of histidine residues in Clostridium perfringens alpha-toxin.