Structure-Function Studies of the Proton-Gated Urea Channel from H. Pylori

幽门螺杆菌质子门控尿素通道的结构功能研究

• 批准号: 7755800
• 负责人: HARTMUT LUECKE
• 金额: $ 48.02万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7755800
• 关键词: Antibiotics; Carboxylic Acids; Clarithromycin; Country; Developed Countries; Development; Docking; Environment; Gastric Adenocarcinoma; Gastric mucosa; Goals; Helicobacter Infections; Helicobacter pylori; Histidine; Human; Hydrogen Bonding; Incidence; Infection; Intervention; Intestinal Diseases; Metronidazole; Mutagenesis; Names; Organism; Patients; Peptic Ulcer; Population; Preventive; Principal Investigator; Proteins; Proton Pump Inhibitors; Protons; Research; Resistance; Resolution; Risk; Stomach; Structure; Structure-Activity Relationship; Testing; Urea; Urease; Work; disorder prevention; inhibitor/antagonist; malignant stomach neoplasm; pathogen; periplasm; prevent; programs; public health relevance; three dimensional structure

DESCRIPTION (provided by applicant): Infection of the gastric mucosa by Helicobacter pylori remains a worldwide problem and contributes to peptic ulcer disease and gastric cancer. Without active intervention, at least 20% of the population of developed countries will continue to be infected by this gastric pathogen. Eradication of the organism would contribute to prevention of disease. Current eradication requires triple therapy, a proton-pump inhibitor and two antibiotics given twice a day for 10 to 14 days. Resistance to either clarithromycin or metronidazole is > 20% and rising. No monotherapy is effective. Gastric infection by H. pylori depends on the expression of a channel unique to this pathogen, UreI. UreI is a proton-gated urea channel necessary for rapid access of urea to intrabacterial urease, essential for maintaining the periplasm at pH 6.1 in the acidic environment of the stomach, as low as pH 2.5, thus allowing colonization of the stomach. Expression of the channel is increased in the stomach. The channel has 193 residues with six transmembrane segments and three periplasmic regions. Mutagenesis studies have shown that the proton gating of UreI is regulated by hydrogen bonding between histidines and carboxylic acid residues in these three periplasmic regions. Obtaining a high-resolution 3-dimensional structure of this channel is the major goal of this work. This will enable understanding of the unique proton-gating mechanism of this protein and will provide a structure to which inhibitors, some of which have been discovered already, can be docked and their structure-activity relationship identified. Inhibition of this channel would be expected to result in specific and effective monotherapy for eradication of the organism and usher in an era of test and treat, rather than only treating symptomatic patients. This would provide a preventive approach to serious upper gastro-intestinal diseases, particularly gastric cancer. PUBLIC HEALTH RELEVANCE Infection of the human stomach by Helicobacter pylori remains an unresolved problem in both the West and underdeveloped countries. Infection increases the risk of developing gastric cancer about 20-fold. Current eradication therapy is cumbersome, requiring twice-a-day administration of a proton-pump inhibitor and two antibiotics. A high-resolution structure of the proton-gated urea channel, UreI, will provide a template for the development of inhibitors that will allow simple targeted monotherapy, allowing a test and treat strategy worldwide to prevent peptic ulcer disease and reduce the incidence of gastric adenocarcinoma.

描述（申请人提供）：幽门螺杆菌感染胃粘膜是一个世界性的问题，并导致消化性溃疡疾病和胃癌。如果不积极干预，发达国家至少有20%的人口将继续感染这种胃病原体。消灭这种有机体将有助于预防疾病。目前的根除需要三联疗法，一种质子泵抑制剂和两种抗生素，每天两次，持续10至14天。对克拉霉素或甲硝唑的耐药性为20%，并且还在上升。没有单一疗法是有效的。幽门螺杆菌引起的胃感染取决于这种病原体所特有的尿路的表达。UreI是一个质子门控的尿素通道，是尿素快速进入细菌内脲酶所必需的，对于维持胃酸性环境中pH为6.1（低至pH为2.5）的周质至关重要，从而允许胃定植。该通道的表达在胃中增加。该通道有193个残基，有6个跨膜段和3个质周区。诱变研究表明，UreI的质子门控是由这三个质周区组氨酸和羧酸残基之间的氢键调节的。获得该通道的高分辨率三维结构是本工作的主要目标。这将有助于理解这种蛋白质独特的质子门控机制，并将提供一种结构，其中一些抑制剂已经被发现，可以停靠并确定它们的结构-活性关系。抑制这一通道有望产生特异性和有效的单一疗法，以根除该生物体，并迎来一个检测和治疗的时代，而不仅仅是治疗有症状的患者。这将为预防严重的上消化道疾病，特别是胃癌提供一种方法。人类胃幽门螺杆菌感染在西方和不发达国家仍然是一个未解决的问题。感染会使患胃癌的风险增加约20倍。目前的根除治疗很麻烦，需要每天两次使用质子泵抑制剂和两种抗生素。质子门控尿素通道（UreI）的高分辨率结构将为抑制剂的开发提供模板，这将允许简单的靶向单药治疗，允许在全球范围内预防消化性溃疡疾病和降低胃腺癌发病率的测试和治疗策略。