STRUCT BAS FOR PEPTIDOGLYCAN RECOGNITION BY HUMAN PEPTIDOGLYCAN RECOGNITION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 肽聚糖识别蛋白(PGRPs)是先天免疫系统的模式识别分子，它结合细菌细胞壁的肽聚糖(PGN)，在某些情况下还能水解肽聚糖(1)。从昆虫到哺乳动物，它们都高度保守。PGRPs以高亲和力结合PGN，是宿主抵御细菌感染的重要贡献者。昆虫PGRPs至少有19个，参与激活信号通路，诱导抗菌肽的表达。相比之下，哺乳动物的PGRPs(其中有四种)不通过宿主信号通路发挥作用，但对革兰氏阳性和阴性细菌都具有直接杀菌作用(1)。事实上，这些PGRPs是一类新的杀菌蛋白，与目前已知的哺乳动物抗菌肽具有不同的结构和作用机制。哺乳动物PgrP-L是一种N-乙酰胞壁酰基-L-丙氨酸酰胺酶，能降解PgN。最近，人们发现PGRP-L也具有促炎作用，与其酰胺酶活性无关(2)。我们以前发表了人PGRP-Ipha和-Ibeta与PGN片段的复合体的结构，并提出了它们杀菌活性的机制(3，4)。我们现在计划将我们的工作扩展到pGRP-L，它含有一个大的N-末端结构域，与其他已知蛋白质没有序列同源性，其结构仍有待确定。PGRP-L结构将提供关于三种不同类型的模式识别分子(PGRP、NOD2和TLR4)如何在细菌病原体的炎症反应中相互依赖的作用的见解。最近，我们获得了一些太小(~50微米)的小晶体，不能用我们的内部探测器进行数据采集。它们的衍射率最高可达7？，单位晶胞尺寸为

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Peptidoglycan recognition proteins (PGRPs) are pattern recognition molecules of the innate immune system that bind and, in certain cases, hydrolyze peptidoglycans (PGNs) of bacterial cell walls (1). They are highly conserved from insects to mammals. PGRPs bind PGNs with high affinity and are important contributors to host defense against bacterial infections. Insects PGRPs, of which there are at least 19, are involved in activating signaling pathways that induce expression of anti-microbial peptides. By contrast, mammalian PGRPs, of which there are four, do not act through host signaling pathways, but are directly bactericidal against both Gram-positive and -negative bacteria (1). Indeed, these PGRPs are a new class of bactericidal proteins that have a different structure and mechanism of action than currently known mammalian antimicrobial peptides. Mammalian PGRP-L is an N-acetylmuramoyl-L-alanine amidase that hydrolyzes PGN. Very recently, it was found that PGRP-L also has a proinflammatory function, unrelated to its amidase activity (2). We previously published structures of human PGRP-Ialpha and -Ibeta in complex with PGN fragments, and have proposed a mechanism for their bactericidal activity (3,4). We now plan to extend our work to PGRP-L, which contains a large N-terminal domain with no sequence homology to other known proteins, and whose structure remains to be established. The PGRP-L structure will provide insights into how three different types of pattern recognition molecules (PGRPs, Nod2 and TLR4) play interdependent roles in inflammatory responses to bacterial pathogens. Recently, We obtained a few small crystals which are too small (~50um) for data collection with our in-house detector. They diffract to a maximum resolution of 7 ¿ with unit cell dimensions of