STRUCTURAL STUDIES ON AMINOGLYCOSIDE PHOSPHOTRANSFERASES

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 抗生素耐药性出现的一个主要因素是存在化学修饰常见抗生素的细菌酶。氨基糖苷类抗生素（如卡那霉素、妥布霉素和庆大霉素）就是目前几乎普遍耐药的一类抗生素。肠球菌对庆大霉素的高水平耐药是由APH（2？）在抗生素上的特定羟基处磷酸化的酶的亚家族。在结构上，氨基糖苷磷酸转移酶具有类似于真核生物Ser/Thr和Tyr蛋白激酶的催化亚基的双结构域结构。 了解这些酶如何结合和失活的氨基糖苷类将提供有价值的信息，这些酶的特异性抑制剂的设计。 我们正在研究所有四个APH（2？）磷酸转移酶，APH（2？）- Ia、APH（2？）Ic和APH（2？）屎肠球菌和APH（2？）-的Id Ic来自E.鸡。 APH（2？）Ib和APH（2？）-已测定了Ic酶。 此外，还从SeMet APH（2？）Ia晶体，结构测定正在进行中。 最近，APH（2？）-我已经长大了，收集了一些数据。

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. A major factor in the emergence of antibiotic resistance is the existence of bacterial enzymes that chemically modify common antibiotics. One such family of anti-bacterials to which there is now almost universal resistance is the aminoglycosides (e.g. kanamycin, tobramycin and gentimicin). High level resistance to gentamicin in enterococci is mediated by a group of four phosphotransferases belonging to the APH(2?) sub-family of enzymes which phosphorylate at a specific hydroxyl group on the antibiotic. Structurally, the aminoglycoside phosphotransferase enzymes have a two-domain architecture resembling the catalytic subunit of the eukaryotic Ser/Thr and Tyr protein kinases. An understanding of how these enzymes bind and deactivate the aminoglycosides will provide valuable information for the design of specific inhibitors of these enzymes. We are studying all four of the APH(2?) phosphotransferases, APH(2?)-Ia, APH(2?)-Ic and APH(2?)-Id from Enterococcus faecium and APH(2?)-Ic from E. gallinarum. The three dimensional structures of the APH(2?)-Ib and APH(2?)-Ic enzymes have been determined. In addition, three wavelength MAD data has been collected from a SeMet APH(2?)-Ia crystal and the structure determination is underway. More recently diffraction quality crystals of APH(2?)-Id have been grown and some data collected.