Spt5

1. Role of Spt5 in
transcriptional regulation
of Toxoplasma gondii
By
G.PAVAN
M.Sc Biochemistry

2. toxoplasma gondii
Toxoplasma gondii is
an obligate
intracellular parasitic
one-celled eukaryote
that causes the
infectious disease
toxoplasmosis..

3. Spt5
• Transcription elongation factor SPT5 is a protein that in humans is
encoded by the SUPT5H gene.
• that promotes promoter-proximal pausing, promoter escape,
elongation, and mRNA processing.
• Spt5, the large subunit of the DRB sensitivity-inducing factor (DSIF),
represses or activates RNAPII elongation in vitro.

4. Why Spt5 protein in transcription
• RNA polymerase II of yeast is a protein of 12 subunits. It catalyzes the
transcription of DNA to the synthesis of mRNA , this enzyme cannot
locate promoters or attach to DNA in a stable fashion . to attach at
the beginnings of genes, However, RNAP II cannot efficiently
transcribe chromatin templates in vitro, so some RNA polymerase II
Must interact with several proteins are called General transcriptional
factors, the proteins are general because they assemble on all
promoters used by RNA polymerase.

5. Organization of Spt5 protein
•Spt5 is a large, highly conserved, multi-domain
protein consisting of an N-terminal acidic domain, a
NusG N-terminal (NGN) domain, multiple Kyprides,
Ouzounis, Woese (KOW) domains and a set of short
repeats at its C-terminus (CTR)

6. Spt5 plays pervasive role in transcription
elongation and their mechanism
•Spt5 tightly associates with RNAPII in a
transcription-dependent manner . In vitro
transcription experiments show that this
association begins just downstream of the
transcription start site.
•Multi-gene and genome-wide ChIP studies also
show that association of Spt5 with genes begins
downstream of transcription start sites, that it
persists until around the site of termination and
that it largely mirrors the distribution of RNAPII .

7. Contd…..
•Spt5 complex also associates with RNA
polymerase and can stimulate elongation of
a 10 subunit (rather than the normal 12)
form of RNA polymerase that is less
processive than the complete complex
under low-nucleotide conditions,
demonstrating that Spt5 functions are
universally conserved.

9. Aim of this project/importance
1.Rate of reaction
(Transcription)
2. mRNA yield

10. REFERENCES
BOOKS
 GENETICS –P.S Verma, V.K .Agarwal
 GENETICS –Pierce
 GENETICS –Russell.
ARTICLES
 The Spt4-Spt5 complex: a multi-faceted regulator of
transcription elongation Grant A Hartzogcorresponding authora
and Jianhua Fub.
 The elongation factor Spt5 facilitates transcription initiation for
rapid induction of inflammatory-response genes Gil Diamant,
Anat Bahat & Rivka Dikstein ,Nature Communications.
 Spt5 and Spt6 are associated with active transcription and have
characteristics of general elongation factors in D.
melanogasterCraig D. Kaplan, James R. Morris, C.-ting Wu, and
Fred Winston1 , GENE Development.

11. • The production of mRNA is a multi-step process that involves
transcription initiation, elongation, and termination . For decades, the
major mechanism of gene regulation in higher eukaryotes is thought
to reside at the level of recruitment of RNAPII by sequence-specific
DNA binding factors, despite the presence of RNAPII proximal to the
promoters of a few genes including hsp70 and HIVLTR in un-induced
conditions. But recently, it has been observed that many
transcriptionally repressed genes have promoter-proximal paused or
stalled RNAPII . Moreover, biochemical studies have identified over a
dozen proteins and a small nuclear RNA, which regulate RNAPII
elongation in vitro .
• Among the identified elongation factors, the DRB-Sensitivity-Inducing-
Factor (DSIF) that is composed of Spt5, can repress and activate
RNAPII elongation on an artificial DNA template under different assay
conditions in vitro .

12. • since Spt4 is a small protein and not essential for yeast survival, most
studies including ours have focused on Spt5. The C-terminal repeat 1
(CTR1) of Spt5 , together with RNAPII C-terminal domain (CTD) and
Negative Elongation Factors (NELF) are targets of phosphorylation by
P-TEFb, a protein kinase composed of CDK9 and Cyclin T subunits,
which reverses elongation repression and promotes positive
elongation.