Affiliation:
1. Curriculum in Genetics and Molecular Biology
2. Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
Abstract
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.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
28 articles.
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