Dataset Information

Structure of a prokaryotic virtual proton pump at 3.2 A resolution.

ABSTRACT: To reach the mammalian gut, enteric bacteria must pass through the stomach. Many such organisms survive exposure to the harsh gastric environment (pH 1.5-4) by mounting extreme acid-resistance responses, one of which, the arginine-dependent system of Escherichia coli, has been studied at levels of cellular physiology, molecular genetics and protein biochemistry. This multiprotein system keeps the cytoplasm above pH 5 during acid challenge by continually pumping protons out of the cell using the free energy of arginine decarboxylation. At the heart of the process is a 'virtual proton pump' in the inner membrane, called AdiC, that imports L-arginine from the gastric juice and exports its decarboxylation product agmatine. AdiC belongs to the APC superfamily of membrane proteins, which transports amino acids, polyamines and organic cations in a multitude of biological roles, including delivery of arginine for nitric oxide synthesis, facilitation of insulin release from pancreatic beta-cells, and, when inappropriately overexpressed, provisioning of certain fast-growing neoplastic cells with amino acids. High-resolution structures and detailed transport mechanisms of APC transporters are currently unknown. Here we describe a crystal structure of AdiC at 3.2 A resolution. The protein is captured in an outward-open, substrate-free conformation with transmembrane architecture remarkably similar to that seen in four other families of apparently unrelated transport proteins.

SUBMITTER: Fang Y

PROVIDER: S-EPMC2745212 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Structure of a prokaryotic virtual proton pump at 3.2 A resolution.

Fang Yiling Y Jayaram Hariharan H Shane Tania T Kolmakova-Partensky Ludmila L Wu Fang F Williams Carole C Xiong Yong Y Miller Christopher C

Nature 20090705 7258

To reach the mammalian gut, enteric bacteria must pass through the stomach. Many such organisms survive exposure to the harsh gastric environment (pH 1.5-4) by mounting extreme acid-resistance responses, one of which, the arginine-dependent system of Escherichia coli, has been studied at levels of cellular physiology, molecular genetics and protein biochemistry. This multiprotein system keeps the cytoplasm above pH 5 during acid challenge by continually pumping protons out of the cell using the ...[more]

PMID: 19578361

Similar Datasets

Project description:Background & aimsRecognition of rumination and supragastric belching is often delayed as symptoms may be mistakenly attributed to gastroesophageal reflux disease. However, distinct from gastroesophageal reflux disease, rumination and supragastric belching are more responsive to behavioral interventions than to acid-suppressive and antireflux therapies. Postprandial high-resolution impedance manometry (PP-HRIM) is an efficient method to identify rumination and belches. We investigated the distribution of postprandial profiles determined by PP-HRIM, and identified patient features associated with postprandial profiles among patients with nonresponse to proton pump inhibitors (PPIs).MethodsWe performed a retrospective analysis of PP-HRIM studies performed on 94 adults (mean age, 50.6 y; 62% female) evaluated for PPI nonresponsiveness at an esophageal referral center, from January 2010 through May 2016. Following a standard esophageal manometry protocol, patients ingested a solid refluxogenic test meal (identified by patients as one that induces symptoms) with postprandial monitoring up to 90 minutes (median, 50 min). Patients were assigned to 1 of 4 postprandial profiles: normal; reflux only (>6 transient lower esophageal sphincter relaxations (TLESRs)/h); supragastric belch (>2 supragastric belches/h), with or without TLESR; or rumination (≥1 rumination episode/h) with or without TLESR and supragastric belching. The primary outcome was postprandial profile.ResultsOf the study participants, 24% had a normal postprandial profile, 14% had a reflux-only profile, 42% had a supragastric belch profile, and 20% had a rumination profile. In multinomial regression analysis, the rumination group most frequently presented with regurgitation, the supragastric belch and rumination groups were younger in age, and the reflux-only group had a lower esophagogastric junction contractile integral. The number of weakly acidic reflux events measured by impedance-pH monitoring in patients receiving PPI therapy was significantly associated with frequency of rumination episodes and supragastric belches.ConclusionsIn a retrospective analysis of 94 nonresponders to PPI therapy evaluated by PP-HRIM, we detected an abnormal postprandial pattern in 76% of cases: 42% of these were characterized as supragastric belching, 20% as rumination, and 14% as reflux only. Age, esophagogastric junction contractility, impedance-pH profiles, and symptom presentation differed significantly among groups. PP-HRIM can be used in the clinic to evaluate mechanisms of PPI nonresponse.

Dataset Information

Structure of a prokaryotic virtual proton pump at 3.2 A resolution.

Publications

Structure of a prokaryotic virtual proton pump at 3.2 A resolution.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets