The rpoZ-spoT-trmH-recG operon in E. coli contais four genes that encode proteins involved in DNA and RNA processing. The operon can be repressed by the RNA polymerase-binding transcription factor DksA - ppGpp complex. This complex forms when levels of ppGpp are increased in the cell, typically in conditions where there is a shortage of amino acids, and it inhibits binding of RNA polymerase to the promoter. This helps to slow bacterial translation, preserving the amino acids that are present. The first gene in the operon, rpoZ, encodes DNA-directed RNA polymerase subunit omega, one of the three different proteins in the DNA-directed RNA polymerase complex. It is used in the cell to promote the assembly of RNA polymerase and the initiation of transcription. The second gene, spoT, encodes the bifunctional (p)ppGpp synthase and hydrolase SpoT, an enzyme that can either produce or degrade ppGpp, depending on the current conditions in the cell. The third gene, trmH, encodes tRNA guanosine-2'-O-methyltransferase, an enzyme that catalyzes the methylation of some tRNAs. The final gene, recG, encodes the ATP-dependent DNA helicase recG, a helicase that is important for both DNA repair and recombination.

Operon: DNA/RNA Processing References