Sutrina Sarah L, Alleyne Lisa, Hoyte Keisher, Blenman Margot
Department of Biological and Chemical Sciences, The University of the West Indies, Cave Hill Campus, Barbados1.
Microbiology (Reading). 2002 Dec;148(Pt 12):3857-3864. doi: 10.1099/00221287-148-12-3857.
A strain of Salmonella typhimurium in which the genes encoding the general phosphoenolpyruvate:sugar phosphotransferase system (PTS) proteins HPr and Enzyme I have been deleted, the normally cryptic gene encoding the fructose-inducible Enzyme I (EI* or EI(fructose)) is expressed, and the fructose repressor protein is inactive (fruR or cra mutant) was studied. This strain lacks HPr and EI, but expresses FPr (DTP) and EI(fructose) constitutively. Since FPr and EI(fructose) can substitute for HPr and EI, the strain grew in minimal liquid medium supplemented with the PTS sugars glucose, fructose, N-acetylglucosamine, mannitol or mannose. However, it showed very poor to negligible growth on the PTS sugar glucitol. It also grew very poorly on the non-PTS sugars maltose, melibiose and especially glycerol. Adding cAMP to the medium allowed growth on glucitol, but did not affect growth on glycerol. We suggest that poor phosphorylation of the regulatory molecule Enzyme IIA(glucose) by FPr is responsible for these effects.
对一株鼠伤寒沙门氏菌进行了研究，该菌株中编码通用磷酸烯醇丙酮酸：糖磷酸转移酶系统（PTS）蛋白HPr和酶I的基因已被删除，编码果糖诱导型酶I（EI*或EI(果糖)）的通常隐秘基因得以表达，且果糖阻遏蛋白无活性（fruR或cra突变体）。该菌株缺乏HPr和EI，但组成型表达FPr（DTP）和EI(果糖)。由于FPr和EI(果糖)可替代HPr和EI，该菌株在补充了PTS糖类葡萄糖、果糖、N - 乙酰葡糖胺、甘露醇或甘露糖的基本液体培养基中生长。然而，它在PTS糖类葡糖醇上的生长非常差甚至可忽略不计。它在非PTS糖类麦芽糖、蜜二糖尤其是甘油上的生长也非常差。向培养基中添加cAMP可使菌株在葡糖醇上生长，但不影响其在甘油上的生长。我们认为FPr对调节分子葡萄糖酶IIA的磷酸化不足是造成这些影响的原因。
