Transcriptional Analysis of the Escherichia coli mreBCD Genes Responsible for Morphogenesis and Chromosome Segregation
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The <I>Escherichia coli mreB</I> gene encodes an actin-like cytoskeletal protein and is required for rod shape formation of cells and chromosome segregation. Just downstream of <I>mreB</I>, the <I>mreC</I> and <I>mreD</I> genes are located. They are also required for rod shape formation, though their role in chromosome segregation is unclear. <I>lacZ</I> fusion analysis and Northern hybridization showed that the <I>mreB</I>, <I>mreC</I>, and <I>mreD</I> genes formed an operon. Most of the transcripts were expressed as a monocistronic <I>mreB</I> mRNA, and only 1–2% of the transcripts were expressed as a polycistronic <I>mreBCD</I> mRNA. Introduction of a frame-shift mutation in the <I>mreB</I> gene resulted in a significant decrease in the amount of polycistronic <I>mreBCD</I> mRNA but not in that of monocistronic <I>mreB</I> mRNA, suggesting that an attenuation-like regulation was involved in this transcriptional control. Primer extension analysis identified three transcriptional initiation sites. Three possible σ<SUP>D</SUP>-dependent promoter-like sequences were found just upstream of these transcriptional initiation sites. <I>lacZ</I> fusion analysis confirmed that these three promoters contributed to the expression of <I>mreBCD</I>. On the basis of these findings, the essentiality of the <I>mreB</I> gene was confirmed.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(11), 2712-2719, 2006-11-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry