Publication Date:
2009-07-07
Description:
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.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745212/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745212/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fang, Yiling -- Jayaram, Hariharan -- Shane, Tania -- Kolmakova-Partensky, Ludmila -- Wu, Fang -- Williams, Carole -- Xiong, Yong -- Miller, Christopher -- P30 EB009998/EB/NIBIB NIH HHS/ -- R01 GM031768/GM/NIGMS NIH HHS/ -- R01 GM031768-26/GM/NIGMS NIH HHS/ -- R01 GM089688/GM/NIGMS NIH HHS/ -- T32 NS 07292/NS/NINDS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2009 Aug 20;460(7258):1040-3. doi: 10.1038/nature08201. Epub 2009 Jul 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19578361" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Sequence
;
Amino Acid Transport Systems/*chemistry/metabolism
;
Antiporters/*chemistry/metabolism
;
Bacterial Proteins/*chemistry
;
Crystallography, X-Ray
;
Escherichia coli/*chemistry
;
Escherichia coli Proteins/*chemistry/metabolism
;
Models, Molecular
;
Molecular Sequence Data
;
Multigene Family
;
Protein Conformation
;
Salmonella typhi/*chemistry
;
Structural Homology, Protein
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
