STRUCTURAL STUDIES ON BETA-LACTAMASE ENZYMES

β-内酰胺酶的结构研究

基本信息

批准号：
8169969
负责人：
CLYDE A SMITH
金额：
$ 0.27万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-05-01 至 2011-02-28
项目状态：
已结题

项目摘要

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. Beta-lactams are the most common antibiotics in clinical use and represent more than 60% of total world consumption of antimicrobial drugs. They include penicillins, cephalosporins, monobactams, penems and carbapenems, and over 50 antibiotics of this class are available on the market. A major mechanism of bacterial resistance to beta-lactam antibiotics is the production of beta-lactamases, enzymes that hydrolyze the conserved four-membered ring of beta-lactams in a two-step process. Firstly the beta-lactam ring is opened and the adduct binds covalently to an active site serine residue (the acylation step). This adduct is then deacylated by a water molecule held in place by a highly conserved glumate residue (Glu166), releasing the inactive peniciloic acid derivative of the drug. We are currently working on two recently-discovered beta-lactamase enzymes. The first, named GES-1 (Guiana Extended-Spectrum, after the country where it was first isolated) was initially described in 2000. This extended spectrum beta-lactamase (ESBL) is very distantly related to other class A beta-lactamases and produces resistance to penicillins and first-, second-, and some third-generation cephalosporins (e.g. ceftazidime) but not to monobactams and carbapenems. Since 2000, nine GES-type enzymes (GES-1 - GES-9) from different geographical locations have been described. The most alarming characteristic of the GES family of enzymes that distinguish them from the TEM and SHV superfamilies, is their apparent ability to evolve into weak carbapenemases, enzymes capable of hydrolyzing carbapenem antibiotics. We determined the GES-1 structure in 2007 and have recently crystallized and determined the structures of two other members of the GES family, GES-2 and GES-5, both of which a single point mutants of the GES-1 enzyme and which show elevated activity against the carbepenem antibiotic imipenem. In addition, we have also determined the structure of a deacylation deficient mutant (E166N) of GES-5. The second enzyme, Oih-1 was isolated

该子项目是利用该技术的众多研究子项目之一资源由 NIH/NCRR 资助的中心拨款提供。子项目及研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金，因此可以在其他 CRISP 条目中表示。列出的机构是对于中心来说，它不一定是研究者的机构。 β-内酰胺类是临床上最常用的抗生素，占世界抗菌药物总消费量的 60% 以上。它们包括青霉素类、头孢菌素类、单菌素类、青霉烯类和碳青霉烯类，市场上有超过 50 种此类抗生素。细菌对β-内酰胺抗生素耐药的一个主要机制是产生β-内酰胺酶，这种酶通过两步过程水解β-内酰胺的保守四元环。首先，β-内酰胺环打开，加合物与活性位点丝氨酸残基共价结合（酰化步骤）。然后，该加合物被高度保守的谷氨酸残基 (Glu166) 固定的水分子脱酰，释放出药物的无活性青霉酸衍生物。我们目前正在研究两种最近发现的 β-内酰胺酶。第一个被命名为 GES-1（圭亚那超广谱，以其首次分离的国家命名）最初于 2000 年被描述。这种超广谱 β-内酰胺酶 (ESBL) 与其他 A 类 β-内酰胺酶关系非常远，并产生对青霉素和第一代、第二代和某些第三代头孢菌素（例如头孢他啶）有耐药性，但对单环菌素和碳青霉烯类。自 2000 年以来，来自不同地理位置的九种 GES 型酶 (GES-1 - GES-9) 已被描述。 GES 酶家族与 TEM 和 SHV 超家族的最令人震惊的特征是它们明显能够进化成弱碳青霉烯酶，即能够水解碳青霉烯类抗生素的酶。我们于 2007 年确定了 GES-1 的结构，最近结晶并确定了 GES 家族其他两个成员 GES-2 和 GES-5 的结构，这两个成员都是 GES-1 酶的单点突变体，并且显示出对抗碳青霉烯类抗生素亚胺培南的活性升高。此外，我们还确定了GES-5的脱酰基缺陷突变体（E166N）的结构。分离出第二种酶 Oih-1