title: Kinase-inducible domain-like region of HTLV type 1 tax is important for NF-kappaB activation.
abstract: Partial proteolysis of HTLV-1 Tax protein has revealed the region surrounding amino acid residues (88)KVL(90) to be highly exposed. The protein sequence surrounding this region ((81)QRTSKTLKVLTPPIT(95)) bears resemblance to the kinase-inducible domain (KID, (129)SRRPSYRKILNE(140)) of CREB and is involved in recruiting transcriptional coactivators, p300 and CBP, for trans-activating the viral long terminal repeat (LTR). Data have also revealed the KID-like region to be important for Tax binding to DNA. Here we report that single (K88A, V89A, L90A) and double alanine substitutions (V89A-L90A) in the (88)KVL(90) motif attenuate the ability of Tax to activate NF-kappaB. Deletions near or spanning this motif also had the same effect. The alanine substitutions affect HTLV-1 LTR activation and NF-kappaB activation differently, with K88A and V89A mutants showing much reduced activities for HTLV LTR activation while retaining attenuated but significant NF-kappaB-activating function. In contrast, although the L90A mutant is similarly attenuated for NF-kappaB activation, it showed significant activity in LTR trans-activation. Incorporation of both V89A and L90A substitutions in a V89A-L90A double mutant further reduced NF-kappaB activation and completely abrogated LTR trans-activation. In aggregate, these results demonstrate the importance of the KID-like domain of Tax and implicate its interaction with cellular factors other than p300/CBP in NF-kappaB activation.
authors.affiliation: Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Kuo
authors.forename: Y
authors.initials: Y
authors.lastname: Tang
authors.forename: R
authors.initials: R
authors.lastname: Harrod
authors.forename: P
authors.initials: P
authors.lastname: Cai
authors.forename: C Z
authors.initials: CZ
authors.lastname: Giam
mesh_terms: D020816:Amino Acid Motifs; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D004789:Enzyme Activation; D016356:Gene Products, tax / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D015368:Human T-lymphotropic virus 1 / Q000502:physiology; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D016328:NF-kappa B / Q000096:biosynthesis*; D010770:Phosphotransferases / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D016356:Gene Products, tax; D016328:NF-kappa B; D008156:Luciferases; D015500:Chloramphenicol O-Acetyltransferase; D010770:Phosphotransferases