肽聚糖识别蛋白(PGRPs)是一类在PGN代谢和抗菌防御中起重要作用的多功能蛋白,它们的功能已经在哺乳动物中得到了很好的表征,骨鱼,和昆虫。然而,有关两栖类长型PGRP功能的信息相当有限。这里,我们从非洲爪蛙中鉴定并克隆了一个长型PGRP基因(命名为Xl-PGRP-L),非洲爪狼.Xl-PGRP-L基因在所有检查的orangs/组织中检测到,并在肠道中迅速诱导,肝脏,和PGN刺激后的肺。序列分析表明,Xl-PGRP-L具有催化PGRP的酰胺酶活性所需的四个Zn2结合残基(His358,Tyr395,His470和Cys478),和酰胺酶活性测定表明,重组Xl-PGRP-L云以Zn2依赖性方式降解PGN,这表明Xl-PGRP-L属于催化PGRP。此外,Xl-PGRP-L对革兰氏阴性菌塔田爱德华氏菌和革兰氏阳性菌无乳链球菌具有抗菌活性。本研究代表了有关两栖动物长型PGRP生物活性的第一个表征,因此有助于更好地了解四足动物PGRPs的功能和两栖动物抗菌防御的分子机制。
Peptidoglycan recognition proteins (PGRPs) are a family of multifunctional proteins playing vital roles in PGN metabolism and antibacterial defense, and their functions have been well-characterized in mammals, bony fishes, and insects. However, the information about the functions of amphibian long-type PGRP is rather limited. Here, we identified and cloned a long-type PGRP gene (named Xl-PGRP-L) from African clawed frog, Xenopus laevis. Xl-PGRP-L gene was detected in all orangs/tissues examined, and was rapidly induced in intestine, liver, and lung following the stimulation of PGN. Sequence analysis showed that Xl-PGRP-L possesses four Zn2+-binding residues (His358, Tyr395, His470, and Cys478) required for amidase activity of catalytic PGRPs, and assays for amidase activity revealed that recombinant Xl-PGRP-L cloud degrade PGN in a Zn2+-dependent manner, indicating that Xl-PGRP-L is belonging to catalytic PGRPs. In addition, Xl-PGRP-L have antibacterial activity against Gram-negative bacteria Edwardsiella tarda and Gram-positive bacteria Streptococcus agalactiae. The present investigation represents the first characterization regarding the biological activities of amphibian long-type PGRPs, thus contributes to a better understanding of the functions of tetrapod PGRPs and the molecular mechanisms of amphibian antibacterial defense.