User:Michelle Meyer BC/S8

The spc operon consists of 12 genes (rplN, rplX, rplE, rpsN, rpsH, rplF, rplR, rpsE, rpmD, rplO, secY, rpmJ) and is autogenously regulated in E. coli by S8 ribosomal protein interaction with an mRNA structure overlapping the third gene element (rplE) This binding inhibits translation of most, though not all genes in the spc operon   The S8 binding site is a mimic of the S8 binding site on 16S rRNA, however experimental studies have shown  the distal portion of the stem may be quite variable. The bulged C5 and U2 within the binding site are suspected to reduce S8 affinity for the mRNA structure, but these bases did not contact the S8 protein in a crystal structure of the mRNA-S8 complex, and the bases are locally flexible. These bases are well conserved, but it is not clear if the conservation is due to functional constraints or rplE overlap.