Complete identity of the cis-asRNA StfZ and its influence on FtsZ protein level and cell division in Escherichia coli

Abstract

Bacteria regulate FtsZ protein levels through transcriptional and translational mechanisms for proper cell division. A cis-antisense RNA, StfZ, produced from the ftsA-ftsZ intergenic region was proposed to regulate the FtsZ level in Escherichia coli. However, its structural identity remained unknown. In the present study, we determined the complete sequence, identified the promoters, and effects of StfZ on the FtsZ level. We show that StfZ is expressed at 1:6 ratio of StfZ:ftsZ mRNA at all growth phases from three promoters as three isoforms of 366 nt, 474 nt, and 552 nt. Overexpression of StfZ reduces FtsZ level, increases cell size, and blocks cell division. Thus, the cis-encoded StfZ emerges as a novel factor for maintaining the FtsZ level at different growth phases in E. coli.