title: Total chemical synthesis of human T-cell leukemia virus type 1 protease via native chemical ligation.
abstract: Human T-cell leukemia virus 1 (HTLV-1) protease, a member of the aspartic acid protease family, plays critical roles in the pathogenesis of the virus and is an attractive viral target for therapeutic intervention. HTLV-1 protease consists of 125 amino acid residues and functions as a homodimer stabilized in part by a four-stranded beta-sheet comprising the N- and C-termini. Compared with many other viral proteases such as HIV-1 protease, HTLV-1 protease is elongated by an extra 10 amino acid residue "tail" at the C-terminus. The structural and functional role of the extra C-terminal residues in the catalysis of HTLV-1 protease has been a subject of debate for years. Using the native chemical ligation technique pioneered by Kent and coworkers, we chemically synthesized a full-length HTLV protease and a C-terminally truncated form encompassing residues 1-116. Enzyme kinetic analysis using three different peptide substrates indicated that truncation of the C-terminal tail lowered the turnover number of the viral enzyme by a factor of 2 and its catalytic efficiency by roughly 10-fold. Our findings differ from the two extreme views that the C-terminal tail of HTLV-1 protease is either fully dispensable or totally required for enzyme dimerization and/or catalysis.
authors.affiliation: Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
authors.forename: Changqing
authors.initials: C
authors.lastname: Li
authors.forename: Xiangqun
authors.initials: X
authors.lastname: Li
authors.forename: Wuyuan
authors.initials: W
authors.lastname: Lu
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D015368:Human T-lymphotropic virus 1 / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D016282:Aspartic Acid Endopeptidases; C079711:HTLV-1 protease