TY - JOUR
T1 - P-TEFb containing cyclin K and Cdk9 can activate transcription via RNA
AU - Lin, Xin
AU - Taube, Ran
AU - Fujinaga, Koh
AU - Matija Peterlin, B.
PY - 2002/5/10
Y1 - 2002/5/10
N2 - Different positive transcription elongation factor b (P-TEFb) complexes isolated from mammalian cells contain a common catalytic subunit (Cdk9) and the unique regulatory cyclins CycT1, CycT2a, CycT2b, or CycK. The role of CycK as a transcriptional cyclin was demonstrated in this study. First, CycK activated transcription when tethered heterologously to RNA, which required the kinase activity of Cdk9. Although this P-TEFb could phosphorylate the C-terminal domain (CTD) of RNA polymerase II (RNAPII) in vitro, in contrast to CycT1 and CycT2, CycK did not activate transcription when tethered to DNA. Interestingly, when the C termini of CycT1 and CycT2 or only the histidine-rich stretch from positions 481 to 551 in CycT1 were added to CycK, the extended chimeras activated transcription equivalently via DNA. Moreover, these transcriptional effects required the CTD of RNAPII in cells. Thus, CycK functions as P-TEFb only via RNA, which suggests the presence of cellular RNA-bound activators that require CycK for their transcriptional activity.
AB - Different positive transcription elongation factor b (P-TEFb) complexes isolated from mammalian cells contain a common catalytic subunit (Cdk9) and the unique regulatory cyclins CycT1, CycT2a, CycT2b, or CycK. The role of CycK as a transcriptional cyclin was demonstrated in this study. First, CycK activated transcription when tethered heterologously to RNA, which required the kinase activity of Cdk9. Although this P-TEFb could phosphorylate the C-terminal domain (CTD) of RNA polymerase II (RNAPII) in vitro, in contrast to CycT1 and CycT2, CycK did not activate transcription when tethered to DNA. Interestingly, when the C termini of CycT1 and CycT2 or only the histidine-rich stretch from positions 481 to 551 in CycT1 were added to CycK, the extended chimeras activated transcription equivalently via DNA. Moreover, these transcriptional effects required the CTD of RNAPII in cells. Thus, CycK functions as P-TEFb only via RNA, which suggests the presence of cellular RNA-bound activators that require CycK for their transcriptional activity.
UR - http://www.scopus.com/inward/record.url?scp=0037053288&partnerID=8YFLogxK
U2 - 10.1074/jbc.M200117200
DO - 10.1074/jbc.M200117200
M3 - Article
C2 - 11884399
AN - SCOPUS:0037053288
VL - 277
SP - 16873
EP - 16878
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 19
ER -