Pelletier G, Frenette M, Vadeboncoeur C
Département de biochimie (Sciences), Université Laval, Québec, Canada.
Microbiology (Reading). 1994 Sep;140 ( Pt 9):2433-8. doi: 10.1099/13500872-140-9-2433.
Streptococcus salivarius transports mannose by a phosphoenolpyruvate:sugar phosphotransferase system (PTS) which consists of a membrane Enzyme II and two forms of Enzyme III (IIIMan) with molecular masses of 38.9 kDa (IIIManH) and 35.2 kDa (IIIManL) respectively. Using a pseudorevertant (strain 57P) isolated from a IIIManL-deficient spontaneous mutant unable to grow on mannose, we demonstrated that S. salivarius could also transport mannose by an inducible fructose PTS. This PTS phosphorylated fructose at the C-1 position with a high affinity (10 microM) and mannose at the C-6 position with a low affinity (200 microM). Derepression of this system in some IIIManL-deficient mutants would explain their ability to grow on mannose.
糖磷酸转移酶系统（PTS）转运甘露糖，该系统由一种膜酶II和两种形式的酶III（IIIMan）组成，分子量分别为38.9 kDa（IIIManH）和35.2 kDa（IIIManL）。利用从一株不能在甘露糖上生长的IIIManL缺陷自发突变体中分离出的假回复体（菌株57P），我们证明唾液链球菌也可以通过诱导型果糖PTS转运甘露糖。该PTS以高亲和力（10 microM）在C-1位磷酸化果糖，以低亲和力（200 microM）在C-6位磷酸化甘露糖。在一些IIIManL缺陷突变体中该系统的去阻遏作用可以解释它们在甘露糖上生长的能力。
