Alternative strategies of 2-deoxyglucose resistance and low affinity glucose transport in the ruminal bacteria, Streptococcus bovis and Selenomonas ruminantium.
Streptococcus bovis and Selenomonas ruminantium grew in the presence of the glucose analog, 2-deoxyglucose (2-DG), but the cells no longer had high affinity glucose transport. In S. bovis, 2-DG resistance was correlated with a decrease in phosphoenolpyruvate (PEP)-dependent glucose phosphotransferase (PTS) activity. The 2-DG-selected S. bovis cells relied solely upon a low affinity, facilitated diffusion mechanism of glucose transport and a 2-DG-resistant glucokinase (ATP-dependent). The glucokinase activity of S. ruminantium was competitively inhibited by 2-DG, and the 2-DG selected cells continued to use PEP-dependent PTS as a mechanism of glucose transport. In this latter case, the 2-DG selected cells switched from a mannosephosphotransferase (enzyme II) that phosphorylated glucose, mannose, and 2-DG, but not alpha-methylglucose to a glucosephosphotransferase (enzyme II) that phosphorylated glucose and alpha-methylglucoside but not 2-DG or mannose. The glucosephosphotransferase (enzyme II) had a very low affinity for glucose and the transport kinetics were similar to the facilitated diffusion system of S. bovis.
Cook
G M
GM
Section of Microbiology, Cornell University, Ithaca, NY 14853.
Russell
J B
JB
D000818:Animals; D001438:Bacteroidaceae / Q000187:drug effects / Q000378:metabolism*; D001667:Binding, Competitive; D003847:Deoxyglucose / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000378:metabolism; D008954:Models, Biological; D010770:Phosphotransferases / Q000096:biosynthesis; D016985:Streptococcus bovis / Q000187:drug effects / Q000378:metabolism*
D003847:Deoxyglucose; D010770:Phosphotransferases; D005947:Glucose