title: Requirement of N- and C-terminal regions for enzymatic activity of human T-cell leukemia virus type I protease.
abstract: The requirement of N- and C-terminal regions for the enzymatic activity of human T-cell leukemia virus type I (HTLV-I) protease was investigated using a series of deletion mutants. The activity was analyzed by autoprocessing of the protease itself or by processing of the gag p53 precursor. The deletional analyses indicated that Asp38-Gly152 with an additional Met-Pro sequence at the N-terminus was probably sufficient for the enzymatic activity, although the mature HTLV-I protease consists of Pro33-Leu157. A molecular model of HTLV-I protease, which was constructed by comparison with the structure of Rous sarcoma virus protease, predicted that Pro33-Leu37 and Gly143-Leu147 would form a beta-sheet. Our experimental results and the model structure suggest that (a) five amino acids in the N-terminal region (Pro33-Leu37), which are thought to be involved in the beta-sheet, are not crucial for the enzymatic activity; (b) Pro153-Leu157 is not necessary but Pro148-Gly152 is important for the enzymatic activity, in addition to Gly143-Leu147 involved in the beta-sheet.
authors.affiliation: Biotechnology Research Laboratories, Takeda Chemical Industries Ltd, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Y
authors.initials: Y
authors.lastname: Misumi
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Fujisawa
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D015683:Gene Products, gag / Q000235:genetics; D016333:HIV Protease / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000201:enzymology*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics
chemical_list: D004279:DNA, Viral; D015683:Gene Products, gag; D016333:HIV Protease