申请人:The Regents of the University of California
公开号:US07238489B2
公开(公告)日:2007-07-03
The present invention is a substantially purified sortase-transamidase enzyme from Gram-positive bacteria, such as Staphylococcus aureus. The enzyme having a molecular weight of about 23,539 daltons and catalyzing a reaction that covalently cross-links the carboxyl terminus of a protein having a sorting signal to the peptidoglycan of a Gram-positive bacterium, the sorting signal having: (1) a motif of LPX3X4G (SEQ ID NO: 37) therein; (2) a substantially hydrophobic domain of at least 31 amino acids carboxyl to the motif; and (3) a charged tail region with at least two positively charged residues carboxyl to the substantially hydrophobic domain, at least one of the two positively charged residues being arginine, the two positively charged residues being located at residues 31-33 from the motif, wherein X3 is any of the twenty naturally-occurring L-amino acids and X4 is selected from the group consisting of alanine, serine, and threonine, and wherein sorting occurs by cleavage between the fourth and fifth residues of the LPX3X4G (SEQ ID NO: 37) motif. Variants of the enzyme, methods for cloning the gene encoding the enzyme and expressing the cloned gene, and methods of use of the enzyme, including for screening for antibiotics and for display of proteins or peptides on the surfaces of Gram-positive bacteria, are also disclosed.
本发明涉及一种来自革兰氏阳性细菌(如金黄色葡萄球菌)的基本纯化的肽酶转酰胺酶酶,该酶的分子量约为23,539道尔顿,催化将具有排序信号的蛋白质的羧基端与革兰氏阳性细菌的肽聚糖共价交联的反应,其中排序信号具有:(1)其中包含LPX3X4G(SEQ ID NO:37)的基序;(2)在基序羧基端至少31个氨基酸的位置上具有基本上疏水的区域;和(3)在基本上疏水的区域羧基端至少有两个带正电荷的残基,其中至少一个带正电荷的残基是精氨酸,两个带正电荷的残基位于基序的第31-33个残基处,其中X3是20种天然L-氨基酸中的任意一种,X4选自丙氨酸,丝氨酸和苏氨酸的群组,其中排序发生在LPX3X4G(SEQ ID NO:37)基序的第四个和第五个残基之间的剪切处。本发明还公开了该酶的变体,克隆编码该酶的基因并表达克隆基因的方法,以及使用该酶的方法,包括筛选抗生素和在革兰氏阳性细菌表面显示蛋白质或肽的方法。