Question

2. To begin transcribing a gene, RNA polymerase has to find and bind to the promoter region. What class of protein co-factors help RNAP do this? (Bonus: what is the term for an RNAP enzyme complexed with one of these?) 3. Name two antibioties that target bacterial ribosomes and describe how they work (Bonus if you do more than two). ABOS

Answer 1

Question 2:

RNA polymerase is an enzyme which transcribes DNA to RNA during transcription. RNA polymerase require essential protein cofactors, called as general transcription factors (GTFs) to copy a DNA sequence to RNA during transcription. GTFs will either bind to promoter or directly to RNA polymerase. Examples, TFIID and SAGA cofactors.

RNA polymerase complexed with GTFs is called as transcription pre-initiation complex and the formation of this complex is a key regulatory step during transcription.

Question 3

Antibiotics that target the bacterial ribosomes include tetracycline and Chloramphenicol.

Mechanism of action of tetracycline: Tetracycline binds to 30S and 50S subunits of bacterial ribosomes and prevent the binding of charged aminoacyl t-RNA tot the acceptor (A) site of the ribosomes. Thus it prevents the growing of the polypeptide chain during protein synthesis and leads to the death of the bacteria.

Mechanism of action of Chloramphenicol: It binds to 23s rRNA of large subunit of bacterial ribosomes (50S) and inhibits ribosomal peptidyl transferase activity. This leads to prevention of peptide bond formation and inhibition of protein synthesis and death of bacteria.