Question

AT-rich sequences are important during transcription. Where are they located and what are there roles?

Answer 1

AT Rich Sequence AT rich sequence is defined as a nucleic aid sequence that contains an above average number of in Adenine denen and Thymine bases. ISP Relevance and Role of AT Rich sequence et edes- A common feature of many bacterial • Origins of replication is the presence of a region lich in adenine and thymone residues. These AT-rich - regions are the sites where the protees of DNA unwinding and replication start in the bacterial cheomosomal origins of replication, the AT-dich regions are a usually located at one side of a clustel of Dnat -boxes and Read the binding site Rx sequences. The AT-rich sequence elements promote nascent transceipt cleavage leading to RNA polymee are 11 temination. AT-lich regions all of different Sizes, depending on the belgin, how ever what seems to be common for them is the size of the initial DNA opening at DUE , which is very ealely longee than 50 bp and not shorter than 20 bp. The great

majority of the AT-rich regions of peokaryotic origins contain repeats of various lengths. They appear to be certical for the origin functioning, and formation of protein complexes during replication initiation events. In the bactelial, oligins, repeats within the AT- sich regions are usually 13 nucleotides long and possess high sequence similarity with consensus determined for E-coli oric 13 nas t They also contain a distinctive cole consisting mostly of NS adenines and thymines at the right hand siale of each repeat. Biotechnical analyses of replication initiation at different origins renaled that the sequence of possibly, the secondary DNA Strenture resulting feom it u absolutely critical for the replicating replicon. However, whether it is the linear oe secondrey Stecture of DNA in the AT-sich region, which is cencial for ceigia's activity and multiprotein ineractions in this region, still requires investigation. Within the repeats of cheomosomal and plarrid AT-rich regions overlapping motifs for binding peoteins engaged in replication initiation and its regerlation were also identified. The analysis of nucleopecten complexes formed at the AT-rich egion of replication eigin will be consial toe hulther undeestanding of the regulation and molecular mechanisms involved in the initial oeigin opening and rearteratsch subsequent steps of replication initiation. . beinitar n o