Inhibition of Tat transactivation by the RNA polymerase II CTD-phosphatase FCP1.
OBJECTIVE
To asses the role of the RNAPII carboxy-terminal domain (CTD) phosphatase FCP1 on HIV-1 Tat-mediated transactivation.


METHODS
Construction of expression vectors encoding FCP1 phosphatase and analysis of their functions on Tat activity.


METHODS
Basal and Tat-mediated transactivation of HIV-1 long terminal repeat (LTR)-driven transcription was compared, by transient transfections, in the presence of FCP1 phosphatase. Protein interactions were analysed by in vitro binding assays.


RESULTS
FCP1 specifically and effectively represses Tat transactivation but not HIV-1 LTR-basal transcription. Protein interaction assays demonstrated that FCP1 specifically and directly binds Tat in vitro.


CONCLUSIONS
The specific and efficient inhibitory function of FCP1 highlights the important role of this CTD-phosphatase in Tat-mediated transactivation, and it suggests that FCP1 might represent a specific target for modulation of Tat activity in infected cells.
Department of Genetics, Molecular and General Biology, University of Naples Federico II and the International Institute of Genetics and Biophysics, Italy.
P
P
Licciardo
G
G
Napolitano
B
B
Majello
L
L
Lania
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D015696:Gene Products, tat / Q000737:chemistry / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D012319:RNA Polymerase II / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D054322:tat Gene Products, Human Immunodeficiency Virus; D012319:RNA Polymerase II; D010749:Phosphoprotein Phosphatases; C116022:carboxy-terminal domain phosphatase