title: Human immunodeficiency virus type 1 subtype C exhibits higher transactivation activity of Tat than subtypes B and E.
abstract: Although human immunodeficiency virus type 1 (HIV-1) subtypes C and E are expanding faster and seem to be of greater global significance than HIV-1 subtype B, there is only little information about Tat activity of such non-B subtypes. Here, we showed evidence that subtype C Tat exhibits higher transcriptional activity from the HIV-1 long-terminal repeat (LTR) in a human T-cell line, compared with subtypes B and E. This higher activity of subtype C Tat was not due to the LTR, but to the Tat sequence variability. We examined three candidate regions with sequence for the higher activity of subtype C Tat, such as the cysteine-rich motif, the basic domain, and the 2nd exon. The results showed that the variation in subtype C Tat at two amino acid residues, Ser57 and Glu63 in stead of Arg57 and Gln63 in subtypes B and E, within and close to the basic domain were involved in the higher activity of subtype C Tat. This variation did not affect its nuclear localization activity. Thus, there may be a significant advantage for the high Tat activity on subtype C replication.
authors.affiliation: Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kurosu
authors.forename: Tetsu
authors.initials: T
authors.lastname: Mukai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Komoto
authors.forename: Madiha S
authors.initials: MS
authors.lastname: Ibrahim
authors.forename: Yong-Gang
authors.initials: YG
authors.lastname: Li
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Shoutaro
authors.initials: S
authors.lastname: Tsuji
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ikuta
mesh_terms: D000595:Amino Acid Sequence; D015496:CD4-Positive T-Lymphocytes; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014644:Genetic Variation; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D054322:tat Gene Products, Human Immunodeficiency Virus