DIFFERENTIAL TRANSLATION OF CELL-DIVISION PROTEINS

Cloned division genes (ftsQ and ftsA) and the gene for β-lactamase (bla) were transcribed in vivo from a bacteriophage T7 promoter under conditions which blocked the use of other promoters. The different coding regions of single mRNAs were translated with widely different efficiencies, such that the ratio of β-lactamase production to FtsQ production was about 75:1. The relative rates of translation of the division proteins reflected their relative rates of production from normal chromosomal promoters (FtsA > FtsQ). We show that the low rates of production of FtsQ and FtsA proteins are due to their ribosome-binding sequences and that there is no obligatory translational coupling between them, despite the close proximity of the genes. Levels of translation of FtsA are shown to be proportional to levels of transcription, and therefore there is no evidence of variable regulation of translation.