Title |
The osmotic stress response operon betIBA is under the functional regulation of BetI and the quorum-sensing regulator AnoR in Acinetobacter nosocomialis |
Author |
Bindu Subhadra1,2, Surya Surendran1,2, Bo Ra Lim1,2, Jong Sung Yim1,2, Dong Ho Kim1,2, Kyungho Woo1,2, Hwa-Jung Kim1,2, Man Hwan Oh3*, and Chul Hee Choi1,2* |
Address |
1Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea, 2Department of Medical Science, Chungnam National University, Daejeon 34134, Republic of Korea, 3Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Republic of Korea |
Bibliography |
Journal of Microbiology, 58(6),519–529, 2020,
|
DOI |
10.1007/s12275-020-0186-1
|
Key Words |
Acinetobacter nosocomialis, osmotic stress, quorum
sensing, BetI |
Abstract |
Adaptation to changing environmental conditions is crucial
for the survival of microorganisms. Bacteria have evolved
various mechanisms to cope with osmotic stress. Here, we
report the identification and functional characterization of
the osmotic stress response operon, betIBA, in Acinetobacter
nosocomialis. The betIBA operon encodes enzymes that are
important for the conversion of choline to the osmoprotectant,
glycine betaine. The betIBA operon is polycistronic
and is under the regulation of the first gene, betI, of the same
operon. A bioinformatics analysis revealed the presence of
a BetI-binding motif upstream of the betIBA operon, and
electrophoretic mobility shift assays confirmed the specific
binding of BetI. An mRNA expression analysis revealed that
expression of betI, betB, and betA genes is elevated in a betIeletion
mutant compared with the wild type, confirming that
the autorepressor BetI represses the betIBA operon in A.
nosocomialis. We further found that the betIBA operon is
under the transcriptional control of the quorum-sensing (QS)
regulator, AnoR in, A. nosocomialis. A subsequent analysis
of the impact of BetI on expression of the QS genes, anoR
and anoI, demonstrated that BetI acts as a repressor of anoR
and anoI. In addition, it was noticed that the osmotic stress
response regulator, OmpR might play an important role in
controlling the expression of betIBA operon in A. nosocomialis.
Collectively, these data demonstrate that QS and osmotic
stress-response systems are correlated in A. nosocomialis
and that the expression of genes in both systems is
finely tuned by various feedback loops depending on osmolarity
conditions. |