Inactivation of the ribonucleic acid-processing enzyme ribonuclease E blocks cell division

The Escherichia coli endoribonuclease ribonuclease E, the enzyme responsible for the processing of precursor 5S ribosomal ribonucleic acid (RNA) from the nascent ribosomal RNA transcript, is thermolabile in rne-3071 mutants. When cells of such a strain were shifted to a nonpermissive temperature, the function of ribonuclease E was almost instantaneously inactivated. However, a threefold linear increase in absorbance took place over a 3-h period, and similar linear increases occurred in all the macromolecules we measured, including deoxyribonucleic acid, RNA, protein, and lipopolysaccharides. Interestingly, during this period, the cells elongated but failed to divide. Thus, these experiments suggest that an early effect of inactivation of the RNA processing enzyme ribonuclease E is a block in cell division.