H. Antelmann et al., Phosphate starvation-inducible proteins of Bacillus subtilis: Proteomics and transcriptional analysis, J BACT, 182(16), 2000, pp. 4478-4490
The phosphate starvation response in Bacillus subtilis was analyzed using t
wo-dimensional (2D) polyacrylamide gel electrophoresis of cell extracts and
supernatants from phosphate-starved cells. Most of the phosphate starvatio
n-induced proteins are under the control of sigma(B), the activity of which
is increased by energy depletion. In order to define the proteins belongin
g to the Pho regulon, which is regulated by the two-component regulatory pr
oteins PhoP and PhoR, the 2D protein pattern of the wild type was compared
with those of a sigB mutant and a phoR mutant. By matrix-assisted laser des
orption ionization-time of flight mass spectrometry, two alkaline phosphata
ses (APases) (PhoA and PhoB), an APase-alkaline phosphodiesterase (PhoD), a
glycerophosphoryl diester phosphodiesterase (GlpQ), and the lipoprotein Yd
hF were identified as very strongly induced PhoPR-dependent proteins secret
ed into the extracellular medium. In the cytoplasmic fraction, PstB1, PstB2
, and TuaD were identified as already known PhoPR-dependent proteins, in ad
dition to PhoB, PhoD, and the previously described PstS. Transcriptional st
udies of glpQ and ydhF confirmed the strong PhoPR dependence. Northern hybr
idization and primer extension experiments showed that glpQ is transcribed
monocistronically from a sigma(A) promoter which is overlapped by four puta
tive TT(A/T)ACA-like PhoP binding sites. Furthermore, ydhF might be cotrans
cribed with phoB initiating from the phoB promoter. Only a small group of p
roteins remained phosphate starvation inducible in both phoR and sigB mutan
t and did not form a unique regulation group. Among these, YfhM and YjbC we
re controlled by sigma(B)-dependent and unknown PhoPR-independent mechanism
s. Furthermore, YtxH and YvyD seemed to be induced after phosphate starvati
on in the wild type in a sigma(B)-dependent manner and in the sigB mutant p
robably via sigma(H). YxiE was induced by phosphate starvation independentl
y of sigma(B) and PhoPR.