Foucaud C, Kunji E R, Hagting A, Richard J, Konings W N, Desmazeaud M, Poolman B
Station de Recherches Laitières, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
J Bacteriol. 1995 Aug;177(16):4652-7. doi: 10.1128/jb.177.16.4652-4657.1995.
A proton motive force-driven di-tripeptide carrier protein (DtpT) and an ATP-dependent oligopeptide transport system (Opp) have been described for Lactococcus lactis MG1363. Using genetically well-defined mutants in which dtpT and/or opp were inactivated, we have now established the presence of a third peptide transport system (DtpP) in L. lactis. The specificity of DtpP partially overlaps that of DtpT. DtpP transports preferentially di- and tripeptides that are composed of hydrophobic (branched-chain amino acid) residues, whereas DtpT has a higher specificity for more-hydrophilic and charged peptides. The toxic dipeptide L-phenylalanyl-beta-chloro-L-alanine has been used to select for a di-tripeptide transport-negative mutant with the delta dtpT strain as a genetic background. This mutant is unable to transport di- and tripeptides but still shows uptake of amino acids and oligopeptides. The DtpP system is induced in the presence of di- and tripeptides containing branched-chain amino acids. The use of ionophores and metabolic inhibitors suggests that, similar to Opp, DtpP-mediated peptide transport is driven by ATP or a related energy-rich phosphorylated intermediate.
已报道乳酸乳球菌MG1363存在质子动力驱动的二肽载体蛋白（DtpT）和ATP依赖的寡肽转运系统（Opp）。利用dtpT和/或opp失活的基因定义明确的突变体，我们现已确定乳酸乳球菌中存在第三种肽转运系统（DtpP）。DtpP的特异性与DtpT部分重叠。DtpP优先转运由疏水（支链氨基酸）残基组成的二肽和三肽，而DtpT对亲水性更强和带电荷的肽具有更高的特异性。有毒二肽L-苯丙氨酰-β-氯-L-丙氨酸已被用于以ΔdtpT菌株为遗传背景筛选二肽-三肽转运阴性突变体。该突变体无法转运二肽和三肽，但仍显示出氨基酸和寡肽的摄取。DtpP系统在含有支链氨基酸的二肽和三肽存在时被诱导。离子载体和代谢抑制剂的使用表明，与Opp类似，DtpP介导的肽转运由ATP或相关的富含能量的磷酸化中间体驱动。
