Positive selection for resistance to 2-deoxyglucose gives rise, in Streptococcus salivarius, to seven classes of pleiotropic mutants, including ptsH and ptsI missense mutants.
We have used the toxic non-metabolizable glucose/mannose analogue 2-deoxyglucose to isolate a comprehensive collection of mutants of the phosphoenolpyruvate:sugar phosphotransferase system from Streptococcus salivarius. To increase the range of possible mutations, we isolated spontaneous mutants on different media containing 2-deoxyglucose and various metabolizable sugars, either lactose, melibiose, galactose or fructose. We found that the frequency at which 2-deoxyglucose-resistant mutants were isolated varied according to the growth substrate. The highest frequency was obtained with the combination galactose and 2-deoxyglucose and was 15-fold higher than the rate observed with the mixture melibiose and 2-deoxyglucose, the combination that gave the lowest frequency. By combining results from: (i) Western blot analysis of IIIMan, a specific component of the phosphoenolpyruvate:mannose phosphotransferase system in S. salivarius; (ii) rocket immunoelectrophoresis of HPr and EI, the two general energy-coupling proteins of the phosphotransferase system; and (iii) from gene sequencing, mutants could be assigned to seven classes.(ABSTRACT TRUNCATED AT 250 WORDS)
Gauthier
L
L
Department of Biochemistry (Sciences), Université Laval, Québec, Canada.
Thomas
S
S
Gagnon
G
G
Frenette
M
M
Trahan
L
L
Vadeboncoeur
C
C
D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003847:Deoxyglucose / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005632:Fructose / Q000494:pharmacology; D005690:Galactose / Q000494:pharmacology; D007122:Immunoelectrophoresis; D007785:Lactose / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics*; D017852:Phosphotransferases (Nitrogenous Group Acceptor) / Q000235:genetics*; D012641:Selection, Genetic; D013291:Streptococcus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development
D001426:Bacterial Proteins; D005632:Fructose; D003847:Deoxyglucose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; C061852:phosphoenolpyruvate-mannitol-specific enzyme III; D017852:Phosphotransferases (Nitrogenous Group Acceptor); C022360:phosphoenolpyruvate-protein phosphotransferase; D007785:Lactose; D005690:Galactose