Arginine-agmatine antiporter in extreme acid resistance in Escherichia coli.
The process of arginine-dependent extreme acid resistance (XAR) is one of several decarboxylase-antiporter systems that protects Escherichia coli and possibly other enteric bacteria from exposure to the strong acid environment of the stomach. Arginine-dependent acid resistance depends on an intracellular proton-utilizing arginine alpha-decarboxylase and a membrane transport protein necessary for delivering arginine to and removing agmatine, its decarboxylation product, from the cytoplasm. The arginine system afforded significant protection to wild-type E. coli cells in our acid shock experiments. The gene coding for the transport protein is identified here as a putative membrane protein of unknown function, YjdE, which we now name adiC. Strains from which this gene is deleted fail to mount arginine-dependent XAR, and they cannot perform coupled transport of arginine and agmatine. Homologues of this gene are found in other bacteria in close proximity to homologues of the arginine decarboxylase in a gene arrangement pattern similar to that in E coli. Evidence for a lysine-dependent XAR system in E. coli is also presented. The protection by lysine, however, is milder than that by arginine.
Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
Ram
R
Iyer
Carole
C
Williams
Christopher
C
Miller
D000376:Agmatine / Q000378:metabolism*; D026905:Amino Acid Transport Systems / Q000235:genetics / Q000378:metabolism*; D017920:Antiporters / Q000235:genetics / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism*; D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D006863:Hydrogen-Ion Concentration
C476528:AdiC protein, E coli; D026905:Amino Acid Transport Systems; D017920:Antiporters; D003470:Culture Media; D029968:Escherichia coli Proteins; D000376:Agmatine; D001120:Arginine