Ye Jing-Jing, Minarcik John, Saier Milton H
Department of Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA.
Microbiology (Reading). 1996 Mar;142 ( Pt 3):585-592. doi: 10.1099/13500872-142-3-585.
Inducer expulsion, a phenomenon in which rapidly metabolizable sugars cause cytoplasmic dephosphorylation and efflux of pre-accumulated sugar-phosphates (sugar-P), has been documented for Streptococcus pyogenes, Streptococcus bovis, and Lactococcus lactis, but not for other Gram-positive bacteria. Using intact cells and membrane vesicles, we show that Enterococcus faecalis exhibits both inducer exclusion and inducer expulsion, and that the latter phenomenon is dependent on the metabolite-activated ATP-dependent HPr(Ser) kinase that phosphorylates Ser-46 in HPr of the phosphotransferase system. A small, heat-stable, membrane-associated, HPr(Ser-P)-activated sugar-P phosphatase (Pase II), previously identified only in Lc. lactis, is shown to be present in extracts of Enterococcus faecalis and Streptococcus pyogenes but not in those of Staphylococcus aureus, Streptococcus mutans, Streptococcus salivarius, or Bacillis subtilis, organisms that do not exhibit the inducer expulsion phenomenon. Further, Lactobacillus brevis, an organism that exhibits inducer expulsion by a different mechanism, also apparently lacks Pase II. The results reveal that Pase II is present in those organisms that exhibit the coupled sugar-P hydrolysis/expulsion mechanism but not those that lack this mechanism. They provide correlative evidence that Pase II initiates inducer expulsion in species of enterococci, streptococci and lactococci.
诱导物排出是一种快速可代谢糖导致细胞质去磷酸化以及预先积累的糖磷酸酯（糖-P）流出的现象，已在化脓性链球菌、牛链球菌和乳酸乳球菌中得到记载，但在其他革兰氏阳性菌中未见报道。利用完整细胞和膜囊泡，我们发现粪肠球菌既表现出诱导物排除又表现出诱导物排出，并且后者现象依赖于代谢物激活的ATP依赖性HPr（Ser）激酶，该激酶使磷酸转移酶系统的HPr中的Ser-46磷酸化。一种小的、热稳定的、与膜相关的、HPr（Ser-P）激活的糖-P磷酸酶（Pase II），此前仅在乳酸乳球菌中鉴定出，被证明存在于粪肠球菌和化脓性链球菌的提取物中，但不存在于金黄色葡萄球菌、变形链球菌、唾液链球菌或枯草芽孢杆菌的提取物中，这些生物体不表现出诱导物排出现象。此外，短乳杆菌是一种通过不同机制表现出诱导物排出的生物体，它显然也缺乏Pase II。结果表明，Pase II存在于那些表现出糖-P水解/排出偶联机制的生物体中，而不存在于缺乏这种机制的生物体中。它们提供了相关证据，表明Pase II在肠球菌、链球菌和乳球菌物种中启动诱导物排出。
