TFIIS
TFII S is an elongation factor that is responsible to stimulate elongation
but not initiation transcription (Weaver, 2002). One primary function
of TFII S is that it allows the RNA polymerase to transcribe through the
pause sites of DNA (Pan et al, 1997 and Weaver, 2002). A pause site
is a site where RNA polymerase pauses at before it continues to transcribe
again (Weaver, 2002). The pause sites are overcome by the binding
of TFII S to RNA polyermase II, followed by the cleaving of the 3’ end of
the nascent RNA. After the cleavage of the nascent RNA chain, the
RNA polymerase then reacts with the new 3’ end, causing the minimization
of the pause sites (Pan et al, 1997).
Besides from helping the RNA polymerase to overcome the pause sites,
TFII S can also proofread and induce the enzyme of RNA polymerase to remove
any mistaken nucleotides (Weaver, 2002).
It was found that eukaryotic TFII S showed a great deal of homologies
among themselves. However, the eukaryotic TFII S does not work with
the bacterial RNA polymerase or vice versa (Shimasaki et al 2000).
TFII S consistsed of three domains: Domain I, Domain II and Domain
III. Domain I is the least conserved among the mammalian species (Shimasaki
et al 2000). Domain II is an alpha – helical region in which it is
a site where the binding of RNA polymerase occurs (Shimasaki et al 2000).
Domain III is the most conserved region among the three domains (Shimasaki
et al 2000). Domain III has a “zinc ribbon motif” that is comparable
to some nuclear polymerases’ subunits (Shimasaki et al 2000).
Structure of Tfiis domain II, elongation factor
Primary citation: Morin, P. E., Awrey, D. E., Edwards,
A. M., Arrowsmith, C. H.: Elongation Factor Tfiis Contains Three Structural
Domains: Solution Structure of Domain II Proc.Nat.Acad.Sci.USA 93 pp. 10604
(1996)
http://www.rcsb.org/pdb/cgi/explore.cgi?pdbId=1ENW
Image on this page was obtained from the Structure database
from the
NCBI
Website.
The image was captured using
Cn3D 3.0
Click on the following links to view a specific transcription factor.
TFIIA
, TFIIB
, TFIID
, TFIIE
, TFIIF
, TFIIH
, TFII I
, TFIIS
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