Regulation of fatty acid biosynthesis by the global regulator C cp A and the local regulator F ab T in S treptococcus mutans

• Published in: Molecular oral microbiology Vol. 30; no. 2; pp. 128 - 146
• Main Authors: Faustoferri, R.C., Hubbard, C.J., Santiago, B., Buckley, A.A., Seifert, T.B., Quivey, R.G.
• Format: Journal Article
• Language: English
• Published: 01-04-2015
• ISSN: 2041-1006; 2041-1014
• DOI: 10.1111/omi.12076

SMU
.1745c, encoding a putative transcriptional regulator of the
M
ar
R
family, maps to a location proximal to the
fab
gene cluster in
S
treptococcus mutans
. Deletion of the
SMU
.1745c (
fab
T
S
m
) coding region resulted in a membrane fatty acid composition comprised of longer‐chained, unsaturated fatty acids (
UFA
), compared with the parent strain. Previous reports have indicated a role for
F
ab
T
in regulation of genes in the
fab
gene cluster in other organisms, through binding to a palindromic
DNA
sequence. Consensus
F
ab
T
motif sequences were identified in
S
. mutans
in the intergenic regions preceding
fab
M
,
fab
T
Sm
and
fab
K
in the
fab
gene cluster. Chloramphenicol acetyltransferase (
cat
) reporter fusions, using the
fab
M
promoter, revealed elevated transcription in a ∆
fab
T
S
m
background. Transcription of
fab
T
S
m
was dramatically elevated in cells grown at p
H
values of 5 and 7 in the ∆
fab
T
S
m
background. Transcription of
fab
T
S
m
was also elevated in a strain carrying a deletion for the carbon catabolite repressor
C
cp
A
. Purified
F
ab
T
S
m
and
C
cp
A
bound to the promoter regions of
fab
T
S
m
and
fab
M
. Hence, the data indicate that
F
ab
T
S
m
acts as a repressor of
fab
M
and
fab
T
S
m
itself and the global regulator
C
cp
A
acts as a repressor for
fab
T
S
m
.