B. Manzanowinkler et al., TFII IS REQUIRED FOR TRANSCRIPTION OF THE NATURALLY TATA-LESS BUT INITIATOR-CONTAINING V-BETA PROMOTER, The Journal of biological chemistry, 271(20), 1996, pp. 12076-12081
The proximal or core promoter of a typical eukaryotic protein coding g
ene comprises distinct elements, TATA and/or initiator (Inr). The exis
tence of TATA or Inr at the core promoter suggests that the mechanism
of transcription initiation mediated by these two genetic elements may
be different. Accordingly, it has been demon strated that the transcr
iptional requirements for the TATA-containing, Inr-less (TATA(+)Inr(-)
) promoters are different from the transcriptional requirements for th
e TATA-less, Inr-containing (TATA(-)Inr(+)) promoters. Although both t
ypes of promoters require the transcription initiation factor (TFIID)
in addition to other common initiation factors, a TATA(-)Inr(+) promot
er requires accessory component(s). Here we have employed in vitro ana
lyses to address the transcription factor requirements for a TATA(-)In
r(+) promoter. We demonstrate that in addition to TFIID, a naturally o
ccurring TATA(-)Inr(+-) promoter requires TFII-I, an Inr element-depen
dent transcription factor. Consistent with its Inr element-dependent a
ctivities, TFII-I is dispensable for a TATA(+)Inr(-) promoter. Further
more, we demonstrate that both TFII-I and TFIID activities in nuclear
extracts are temperature-sensitive. However, TFII-I is heat-inactivate
d at temperatures lower than that required to inactivate TFIID. Theref
ore, differential heat treatment of nuclear extracts provides an assay
to discriminate between transcriptional requirements at TATA(+)Inr(-)
and TATA(-)Inr(+) promoters.