Affiliation:
1. Wadsworth Center, New York State Department of Health
2. Department of Biomedical Sciences, University at Albany, SUNY, Albany, New York
Abstract
ABSTRACT
Little is known about how
Mycobacterium tuberculosis
regulates gene expression in response to its host environment, despite its importance as a pathogen. We previously characterized 10
a
cr
-
c
oregulated
g
enes (ACGs), all of which belong to the DevR (DosR) “dormancy” regulon, and identified one to three copies of a conserved 18-bp palindromic DNA motif in the promoter of each ACG family member. In the present study, we used base substitution analyses to assess the importance of individual motif copies and to identify additional regulatory sequences in five ACG promoters. Regulation of
acr
,
acg
, Rv2623,
narK2
, and Rv1738 was examined by using single-copy
M. tuberculosis
promoter-
lacZ
reporter constructs in
Mycobacterium bovis
BCG under conditions of ambient air versus hypoxia, each in shaking versus standing shallow culture conditions. We found that regulation of these ACG promoters is more heterogeneous than expected and is controlled at multiple levels. In addition to the positive regulation previously associated with DevR (DosR) and the 18-bp ACG motif, we identified negative regulation associated with sequences in the 5′ untranslated regions of
acg
and Rv2623 and positive regulation associated with far upstream regulatory regions of
narK2
and Rv1738. The importance of individual ACG motifs varied among the promoters examined, and Rv1738 was exceptional in that its ACG motif copies were associated with negative, rather than positive, regulation under some conditions. Further understanding of this important regulon requires the identification of additional regulators that compete and/or collaborate with DevR (DosR) to regulate its individual gene members.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
33 articles.
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