Highly conserved configuration of catalytic amino acid residues among calicivirus-encoded proteases.
A common feature of caliciviruses is the proteolytic processing of the viral polyprotein catalyzed by the viral 3C-like protease encoded in open reading frame 1 (ORF1). Here we report the identification and structural characterization of the protease domains and amino acid residues in sapovirus (SaV) and feline calicivirus (FCV). The in vitro expression and processing of a panel of truncated ORF1 polyproteins and corresponding mutant forms showed that the functional protease domain is 146 amino acids (aa) in SaV and 154 aa in FCV. Site-directed mutagenesis of the protease domains identified four amino acid residues essential to protease activities: H(31), E(52), C(116), and H(131) in SaV and H(39), E(60), C(122), and H(137) in FCV. A computer-assisted structural analysis showed that despite high levels of diversity in the primary structures of the protease domains in the family Caliciviridae, the configurations of the H, E, C, and H residues are highly conserved, with these residues positioned closely along the inner surface of the potential binding cleft for the substrate. These results strongly suggest that the H, E, C, and H residues are involved in the formation of a conserved catalytic surface of the SaV and FCV 3C-like proteases.
Oka
Tomoichiro
T
Department of Virology II, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashi-murayama, Tokyo 208-0011, Japan. oka-t@nih.go.jp
Yamamoto
Mami
M
Yokoyama
Masaru
M
Ogawa
Satoko
S
Hansman
Grant S
GS
Katayama
Kazuhiko
K
Miyashita
Kana
K
Takagi
Hirotaka
H
Tohya
Yukinobu
Y
Sato
Hironori
H
Takeda
Naokazu
N
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D017927:Calicivirus, Feline / Q000201:enzymology / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D002415:Cats; D002460:Cell Line; D006801:Humans; D021621:Imaging, Three-Dimensional; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D016366:Open Reading Frames; D010447:Peptide Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D029341:Sapovirus / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity / Q000235:genetics; D014763:Viral Matrix Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D014763:Viral Matrix Proteins; D010447:Peptide Hydrolases