Phosphorylation of the cell division protein GpsB regulates PrkC kinase activity through a negative feedback loop in B acillus subtilis

• Published in: Molecular microbiology Vol. 97; no. 1; pp. 139 - 150
• Main Authors: Pompeo, Frédérique, Foulquier, Elodie, Serrano, Bastien, Grangeasse, Christophe, Galinier, Anne
• Format: Journal Article
• Language: English
• Published: 01-07-2015
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.13015

Although many membrane
S
er/
T
hr‐kinases with
PASTA
motifs have been shown to control bacterial cell division and morphogenesis, inactivation of the
S
er/
T
hr‐kinase
PrkC
does not impact
B
acillus subtilis
cell division. In this study, we show that
PrkC
localizes at the division septum. In addition, three proteins involved in cell division/elongation,
GpsB
,
DivIVA
and
EzrA
are required for stimulating
PrkC
activity
in vivo
. We show that
GpsB
interacts with the catalytic subunit of
PrkC
that, in turn, phosphorylates
GpsB
. These observations are not made with
DivIVA
and
EzrA
. Consistent with the phosphorylated residue previously detected for
GpsB
in a high‐throughput phosphoproteomic analysis of
B
. subtilis
, we show that threonine 75 is the single
PrkC
‐mediated phosphorylation site in
GpsB
. Importantly, the substitution of this threonine by a phospho‐mimetic residue induces a loss of
PrkC
kinase activity
in vivo
and a reduced growth under high salt conditions as observed for
gpsB
and
prkC
null mutants. Conversely, substitution of threonine 75 by a phospho‐ablative residue does not induce such growth and
PrkC
kinase activity defects. Altogether, these data show that proteins of the divisome control
PrkC
activity and thereby phosphorylation of
PrkC
substrates through a negative feedback loop in
B
. subtilis
.