Schönert Stefan, Seitz Sabine, Krafft Holger, Feuerbaum Eva-Anne, Andernach Iris, Witz Gabriele, Dahl Michael K
Lehrstuhl für Mikrobiologie, Fachbereich Biologie der Universität Konstanz, Universitätsstrasse 10, M605, D-78457 Konstanz, Germany.
J Bacteriol. 2006 Jun;188(11):3911-22. doi: 10.1128/JB.00213-06.
Bacillus subtilis can utilize maltose and maltodextrins that are derived from polysaccharides, like starch or glycogen. In this work, we show that maltose is taken up by a member of the phosphoenolpyruvate-dependent phosphotransferase system and maltodextrins are taken up by a maltodextrin-specific ABC transporter. Uptake of maltose by the phosphoenolpyruvate-dependent phosphotransferase system is mediated by maltose-specific enzyme IICB (MalP; synonym, GlvC), with an apparent K(m) of 5 microM and a V(max) of 91 nmol . min(-1) . (10(10) CFU)(-1). The maltodextrin-specific ABC transporter is composed of the maltodextrin binding protein MdxE (formerly YvdG), with affinities in the low micromolar range for maltodextrins, and the membrane-spanning components MdxF and MdxG (formerly YvdH and YvdI, respectively), as well as the energizing ATPase MsmX. Maltotriose transport occurs with an apparent K(m) of 1.4 microM and a V(max) of 4.7 nmol . min(-1) . (10(10) CFU)(-1).
枯草芽孢杆菌能够利用源自多糖（如淀粉或糖原）的麦芽糖和麦芽糊精。在本研究中，我们发现麦芽糖通过磷酸烯醇式丙酮酸依赖性磷酸转移酶系统的一个成员进行摄取，而麦芽糊精则通过麦芽糊精特异性ABC转运蛋白进行摄取。磷酸烯醇式丙酮酸依赖性磷酸转移酶系统对麦芽糖的摄取由麦芽糖特异性酶IICB（MalP；同义词，GlvC）介导，其表观K(m)为5微摩尔，V(max)为91纳摩尔·分钟(-1)·(10(10)CFU)(-1)。麦芽糊精特异性ABC转运蛋白由麦芽糊精结合蛋白MdxE（以前称为YvdG）组成，其对麦芽糊精的亲和力在低微摩尔范围内，还有跨膜成分MdxF和MdxG（以前分别称为YvdH和YvdI）以及供能ATP酶MsmX。麦芽三糖的转运表观K(m)为1.4微摩尔，V(max)为4.7纳摩尔·分钟(-1)·(10(10)CFU)(-1)。
