Saier M H, Yamada M, Erni B, Suda K, Lengeler J, Ebner R, Argos P, Rak B, Schnetz K, Lee C A
Department of Biology, USCD, La Jolla, California 92093.
FASEB J. 1988 Mar 1;2(3):199-208. doi: 10.1096/fasebj.2.3.2832233.
The amino acyl sequences of eight permeases (enzymes II and enzyme II-III pairs) of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) have been analyzed. All systems show similar sizes, and six of these systems exhibit the same molecular weight +/- 2%. Several exhibit sequence homology. Characteristic NH2-terminal and COOH-terminal sequences were found. The NH2-terminal leader sequences are believed to function in targeting of the permeases to the membrane, whereas the characteristic COOH-terminal sequences are postulated to mediate interaction with the energy-coupling protein phospho HPr. One of the systems, the one specific for mannose, exhibits distinctive characteristics. A pair of probable phosphorylation sites was detected in each of the five most similar systems, those specific for beta-glucosides, sucrose, glucose, N-acetylglucosamine, and mannitol. One of the two equivalent phosphorylation sites (proposed phosphorylation site 1) was located approximately 80 residues from the COOH terminus of each system. The other site (proposed phosphorylation site 2) was located approximately 440 residues from the COOH termini of the glucose and N-acetylglucosamine systems, approximately 320 residues from the COOH termini of the beta-glucoside and sucrose systems, and 381 residues from the COOH terminus of the mannitol system. Intragenic rearrangement during evolutionary history may account for the different positions of phosphorylation sites 2 in the different PTS permeases. More extensive intragenic rearrangements may have given rise to entirely different positions of phosphorylation in the glucitol, mannose, and lactose systems. A single, internal amphipathic alpha-helix with characteristic features was found in each of seven of the eight enzymes II. The lactose-specific enzyme III of Staphylococcus aureus was unique in possessing a COOH-terminal amphipathic alpha-helix rich in basic amino acyl residues. Possible functions for these amphipathic segments are discussed.
糖磷酸转移酶系统（PTS）的8种通透酶（酶II和酶II - III对）的氨酰基序列进行了分析。所有系统显示出相似的大小，其中6个系统的分子量相同，误差在±2%以内。有几个系统表现出序列同源性。发现了特征性的氨基末端和羧基末端序列。氨基末端前导序列被认为在将通透酶靶向到膜上起作用，而特征性的羧基末端序列被假定介导与能量偶联蛋白磷酸 - HPr的相互作用。其中一个系统，即对甘露糖特异的系统，表现出独特的特征。在五个最相似的系统中，即对β - 葡萄糖苷、蔗糖、葡萄糖、N - 乙酰葡糖胺和甘露醇特异的系统中，每个系统都检测到一对可能的磷酸化位点。两个等效磷酸化位点之一（提议的磷酸化位点1）位于每个系统羧基末端约80个残基处。另一个位点（提议的磷酸化位点2）位于葡萄糖和N - 乙酰葡糖胺系统羧基末端约440个残基处，β - 葡萄糖苷和蔗糖系统羧基末端约320个残基处，以及甘露醇系统羧基末端381个残基处。进化历史中的基因内重排可能解释了不同PTS通透酶中磷酸化位点2的不同位置。更广泛的基因内重排可能导致了葡糖醇、甘露糖和乳糖系统中磷酸化位置完全不同。在8种酶II中的7种中，每种都发现了一个具有特征的单一内部两亲性α - 螺旋。金黄色葡萄球菌的乳糖特异性酶III独特之处在于其羧基末端富含碱性氨酰基残基的两亲性α - 螺旋。讨论了这些两亲性片段的可能功能。
