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Regulation of Gene Expression via the Core Promoter and the Basal Transcriptional Machinery:

Regulation of Gene Expression via the Core Promoter and the Basal Transcriptional Machinery Oluwadamilola Balogun : u1152857 Edna Rodrigues : u1148530 Tolani Sule-Odu : u1144459 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830304/

Introduction:

I ntroduction The core promoter lies at the center of the transcription process, yet it is often an overlooked component in the regulation of gene expression The core promoter is generally defined to be the DNA region that directs the accurate initiation of transcription by RNA polymerase II. In the past, the core promoter has often been presumed to be a generic entity that functions by a single universal mechanism, but it is now clearly apparent that there is widespread diversity in core promoter structure and function . Caudal is a key regulator of the homeotic gene network that prefrentially activates transcription from DPE than TATA dependent promoters.

Focus vs. Dispersed Transcription:

Focus vs. Dispersed Transcription .

Components (motifs)of a typical RNA Polymerase II core promoter.:

Components (motifs)of a typical RNA Polymerase II core promoter. Initiator ( inr ) : Point at which transcription starts. Connoted as +1 TATA Box and BRE motifs : TATA box is the best core motif. Located at -31 to +30. Conserved from archeabacteria to humans. Bre can be found upstream or downstream of TATA box and work in conjunction with them. DPE and MTE motifs: The DPE is found downstream of the inr located from +28 to +33. It is conserved from Drosophilla to humans. MTE can be found upstream of the DPE (+18 to +27). Basal transcription factors:TFIIA , TFIIB, TFIID, TFIIE, TFIIF, AND TFIIH, NC2.

Role of Core Promoter in Regulation of Gene Expression:

Role of Core Promoter in Regulation of Gene Expression Analysis of the drosophila ( hox ) genes has revealed new insights into the role of the Core promoter in a regulatory network. Caudal is a sequence specific DNA-binding transcription factor and key regulator of The Hox genes.

TATA and DPE specific activators.:

TATA and DPE specific activators.

TRFs (TBP related factors) and Transcriptional Regulation:

TRFs (TBP related factors) and Transcriptional Regulation There is diversity not only in core promoter elements, but also in the basal transcription machinery. There are three TRFs, which are generally termed TRF1, TRF2, and TRF3. TRF 1 : TRF1 does not exist in yeast and humans, but is present in Drosophila. In many eukaryotes, including yeast and humans, TBP participates in transcription by RNA polymerases I, II, and III. However, in Drosophila, TRF1 is used instead of TBP for RNA polymerase III transcription. TRF 2: is present in most eukaryotes, and is involved in transcription by RNA polymerase II. TRF2 does not bind to TATA box sequences, and cannot replace TBP in vitro. It appears that many genes are regulated by TRF2 instead of TBP – one such example is the Drosophila histone H1 gene . TRF 3: appears to be present only in vertebrates, and is the TRF that is most closely related to TBP. TRF3 can bind to TATA boxes and support TATA-dependent transcription.

Conclusion :

Conclusion The core promoter and the basal transcriptional machinery are two important yet relatively unexplored dimensions in the regulation of gene expression. It is now apparent that diversity in the structure and function of core promoters and basal transcription factors contributes to developmental processes that lead to organismal complexity . Therefore, in the future, it will Be essential to consider and to incorporate these factors in the analysis of gene regulation. The increased appreciation and understanding of core promoter motifs and basal transcription factors will lead to new and exciting discoveries, and ultimately, provide a more complete and accurate view of biological regulation.

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