Transcriptional Analysis of the Conserved ftsZ Gene Cluster in Mycoplasma genitalium and Mycoplasma pneumoniae

Abstract

Several experimental approaches were used to construct a detailed transcriptional profile of the phylogenetically conserved ftsZ cell division gene cluster in both Mycoplasma genitalium and its closest relative, Mycoplasma pneumoniae. We determined initiation and termination points for the cluster, as well as an absolute steady-state RNA level for each gene. Transcription of this cluster in both these organisms was shown to be highly strand specific. While the four genes in this cluster are cotranscribed, their transcription unit also includes two genes of close proximity yet disparate function. A transcription initiation point immediately upstream of these two genes was detected in M. genitalium but not M. pneumoniae. In M. pneumoniae, transcription of the six genes terminates at a poly(U)-tailed hairpin. In M. genitalium, this transcription terminates at two closely spaced points by an unknown mechanism. Real-time reverse transcription-PCR analysis of this cluster in M. pneumoniae shows that mRNA levels for all six genes vary at most fivefold and form a gradient of decreasing quantity with increasing distance from the promoter at the beginning of the cluster. mRNA from coding regions was approximately 20-to 100-fold more abundant than that from intergenic regions. We estimated the most abundant mRNA we detected at 0.6 copy per cell. We conclude that groups of functionally related genes in M. genitalium and M. pneumoniae are often preceded by promoters but rarely followed by terminators. This causes functionally unrelated genes to be commonly cotranscribed in these organisms.

Detection and quantification of intergenic transcription in Mycoplasma hyopneumoniae

“…This was unexpected and indicated that M. hyopneumoniae does not strictly control transcription termination as previously suggested (Washio et al, 1998). These studies are supported by recent studies with M. pneumoniae in which IG transcripts on a global scale were also identified by tiling microarrays (Güell et al, 2009) and on a limited scale with Mycoplasma genitalium and M. pneumoniae (Benders et al, 2005). From a physiological standpoint, the lack of transcription termination seems energetically wasteful, suggesting that mycoplasmas may have important roles for these transcripts, such as the generation of small regulatory peptides or RNAs that have yet to be defined in these organisms.…”

“…DNA replication, transcription and translation, are thought to be constitutively expressed, and in constant environments, the organism supposedly has little need for sophisticated genetic control mechanisms (Muto & Ushida, 2002). Our knowledge of gene expression in mycoplasmas is rudimentary, with few studies that actually address the mechanisms involved (Benders et al, 2005;Chang et al, 2008;Güell et al, 2009;Lluch-Senar et al, 2007;Weiner et al, 2000Weiner et al, , 2003. Transcription is essential to the basic process of gene expression, but surprisingly, little information has been obtained experimentally defining the transcription process in mycoplasmas (Muto & Ushida, 2002).…”

Strand-specific deep sequencing of the transcriptome

“…5A). Benders et al (2005) have previously provided an indepth description of the ftsZ locus in the M129 strain, using standard molecular biology techniques. We compared DSSS to their published results.…”

Genes involved in cell division in mycoplasmas

“…In mycoplasmas, which lack a cell wall, the number of genes in this cluster is much lower (Benders et al, 2005). The ftsL, ftsI, ftsW and ftsQ gene products are all transmembrane proteins with the bulk of the proteins extended to the periplasm, and are involved in peptidoglycan synthesis during division (Weiss, 2004).…”

“…Most of them are parasites of a wide group of organisms, including mammals, birds, reptiles, arthropods, fish, and plants (Razin et al, 1998). Only a few studies on Mollicutes have been dedicated to genes involved in cell division, particularly the gene fstZ (Wang and Lutkenhaus, 1996;Kukekova et al, 1999;Momynaliev et al, 2002;Benders et al, 2005). This gene is present in all mycoplasma genomes analyzed so far, with the exception of Ureaplasma urealyticum serovar 3 and Mycoplasma mobile (Glass et al, 2000, Jaffe et al, 2004.…”