title: C-terminal residues of mature human T-lymphotropic virus type 1 protease are critical for dimerization and catalytic activity.
abstract: HTLV-1 [HTLV (human T-cell lymphotrophic virus) type 1] is associated with a number of human diseases. HTLV-1 protease is essential for virus replication, and similarly to HIV-1 protease, it is a potential target for chemotherapy. The primary sequence of HTLV-1 protease is substantially longer compared with that of HIV-1 protease, and the role of the ten C-terminal residues is controversial. We have expressed C-terminally-truncated forms of HTLV-1 protease with and without N-terminal His tags. Removal of five of the C-terminal residues caused a 4-40-fold decrease in specificity constants, whereas the removal of an additional five C-terminal residues rendered the protease completely inactive. The addition of the N-terminal His tag dramatically decreased the activity of HTLV-1 protease forms. Pull-down experiments carried out with His-tagged forms, gel-filtration experiments and dimerization assays provided the first unequivocal experimental results for the role of the C-terminal residues in dimerization of the enzyme. There is a hydrophobic tunnel on the surface of HTLV-1 protease close to the C-terminal ends that is absent in the HIV-1 protease. This hydrophobic tunnel can accommodate the extra C-terminal residues of HTLV-1 protease, which was predicted to stabilize the dimer of the full-length enzyme and provides an alternative target site for protease inhibition.
authors.affiliation: Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen H-4012, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Kádas
authors.forename: Péter
authors.initials: P
authors.lastname: Boross
authors.forename: Irene T
authors.initials: IT
authors.lastname: Weber
authors.forename: Péter
authors.initials: P
authors.lastname: Bagossi
authors.forename: Krisztina
authors.initials: K
authors.lastname: Matúz
authors.forename: József
authors.initials: J
authors.lastname: Tözsér
mesh_terms: D000595:Amino Acid Sequence; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D015368:Human T-lymphotropic virus 1 / Q000201:enzymology*; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D007527:Isoenzymes; D016282:Aspartic Acid Endopeptidases; C079711:HTLV-1 protease