TY - JOUR
T1 - Characterization of glucose-specific catabolite repression-resistant mutants of Bacillus subtilis
T2 - identification of a novel hexose:H+ symporter
AU - Paulsen, Ian T.
AU - Chauvaux, Sylvie
AU - Choi, Peter
AU - Saier, Milton H.
PY - 1998/2
Y1 - 1998/2
N2 - Insertional mutagenesis was conducted on Bacillus subtilis cells to screen for mutants resistant to catabolite repression. Three classes of mutants that were resistant to glucose-promoted but not mannitol-promoted catabolite repression were identified. Cloning and sequencing of the mutated genes revealed that the mutations occurred in the structural genes for (i) enzyme II of the phosphoenolpyruvate-glucose phosphotransferase (PtsG), (ii) antiterminator GIcT, which controls PtsG synthesis, and (iii) a previously uncharacterized carrier of the major facilitator superfamily, which we have designated GIcP. The last protein exhibits greatest sequence similarity to the fucose:H+ symporter of Escherichia coil and the glucose/galactose:H+ symporter of Brucella abortus. In a wild-type B. subtilis genetic background, the glcP::Tn10 mutation (i) partially but specifically relieved glucose- and sucrose-promoted catabolite repression, (ii) reduced the growth rate in minimal glucose medium, and (iii) reduced rates of [14C]glucose and [14C]methyl α-glucoside uptake. In a Δpts genetic background no phenotype was observed, suggesting that expression of the glcP gene required a functional phosphotransferase system. When overproduced in a Δpts mutant of E. coli, GlcP could be shown to specifically transport glucose, mannose, 2- deoxyglucose and methyl α-glucoside with low micromolar affinities. Accumulation of the nonmetabolizable glucose analogs was demonstrated, and inhibitor studies suggested a dependency on the proton motive force. We conclude that B. subtilis possesses at least two distinct routes of glucose entry, both of which contribute to the phenomenon of catabolite repression.
AB - Insertional mutagenesis was conducted on Bacillus subtilis cells to screen for mutants resistant to catabolite repression. Three classes of mutants that were resistant to glucose-promoted but not mannitol-promoted catabolite repression were identified. Cloning and sequencing of the mutated genes revealed that the mutations occurred in the structural genes for (i) enzyme II of the phosphoenolpyruvate-glucose phosphotransferase (PtsG), (ii) antiterminator GIcT, which controls PtsG synthesis, and (iii) a previously uncharacterized carrier of the major facilitator superfamily, which we have designated GIcP. The last protein exhibits greatest sequence similarity to the fucose:H+ symporter of Escherichia coil and the glucose/galactose:H+ symporter of Brucella abortus. In a wild-type B. subtilis genetic background, the glcP::Tn10 mutation (i) partially but specifically relieved glucose- and sucrose-promoted catabolite repression, (ii) reduced the growth rate in minimal glucose medium, and (iii) reduced rates of [14C]glucose and [14C]methyl α-glucoside uptake. In a Δpts genetic background no phenotype was observed, suggesting that expression of the glcP gene required a functional phosphotransferase system. When overproduced in a Δpts mutant of E. coli, GlcP could be shown to specifically transport glucose, mannose, 2- deoxyglucose and methyl α-glucoside with low micromolar affinities. Accumulation of the nonmetabolizable glucose analogs was demonstrated, and inhibitor studies suggested a dependency on the proton motive force. We conclude that B. subtilis possesses at least two distinct routes of glucose entry, both of which contribute to the phenomenon of catabolite repression.
UR - http://www.scopus.com/inward/record.url?scp=0031935564&partnerID=8YFLogxK
M3 - Article
VL - 180
SP - 498
EP - 504
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 3
ER -