Question

Two RNA sequences that can cause premature transcription termination are the trp leader sequence (trp L) in E. coli and the thi riboswitch in B. subtilis. For each of these RNAs, discuss how alternate secondary structures impact termination and describe the conditions that favor each of the alternate secondary structures.

Answer 1

leader sequence is called Atenuation. beanscriptional tiuninator. If pairing / cewe belure Feyeon 3 and 2 During translation coupled to transcription of the polyclotronie mRNA, the ribosomes attach to the mRNA and start feranslation and slowly synthesize the leader peptide and this position of the na ribosome preverite the sequence 3e and instead sequence Answer In case of Trp operona the process of przematito. franzeription lesemination of allermate Secon- by the formation The s'end of the policistronic Mena I trp operon transcribed from the consists of a leader sequence upstream of the Tripe of the coding region gene. The leader sequeence encode a probeer of t4 amino acid residue leadethadeptides de containing 2 trepto tryptophan residue. The leader sequence contains. 4 regions which are denoted from form a ariety of base pair stem wop complementarily. 1 and 2, interacking with sequence to their 1-4 region, Chairpin) secondary structure due sequence Region 3 to complementary to both region 2 and region 4. If Seegion 3 and region 4 base pair with each other, they form a look like sfreudere called attenuator and it function thens anti termination signal és that transcription continue generated with Franslation Stopping eventually between sequence 2 from

in sequence 1, which leaves sequence 2 called the expression platform. transcription forminator. Therefore But if feep absent oren short supply ribosome pauses at the 2 trep codons The riboswitches are structures containing 2 distinet components inds! 3 baise paires with sequence & to form a 3:4 stem coop which acts as a todeneset câu the prescenedlagt kryptophan, branscription of the trip further operon is prevented the free to pair with sequence 3 which and feither interesus aliption of gives Trip tup operon continues ribosome 3 High Termination of transcription Top codon Ribosome Top codon. 2/ 1 low Tre Elongation of transcription Attenuation (Tep. Operon) The thi riboswitch Cabo known as the the box rubo switch appeared to control, inducing traperiton termination treanslation in buram 6) bacteria an aptalhner that detects and binds to specific ligand molecules and bio-sensor, which the a change Conformation of the other component which forms an alternative RNĂ structure that could en causes mainly ach as a

Sequestore Of. RBS. uy or sequester of the operon the shine and models be an 'an iyantiterminator uz auto- int terminatore In case of thi Stimulating low micro TPP is observed the thiamin gene ir negalinty controlled theamin and app) andd bey an evolutionary conserved 34 nucleotide sequence e called the the box a which has the ability to fold into similar hairpin tream criptional seegulation of gene exprusion effect gene expression is regulated bey