title: Chemotaxis of Escherichia coli to norepinephrine (NE) requires conversion of NE to 3,4-dihydroxymandelic acid.
abstract: Norepinephrine (NE), the primary neurotransmitter of the sympathetic nervous system, has been reported to be a chemoattractant for enterohemorrhagic Escherichia coli (EHEC). Here we show that nonpathogenic E. coli K-12 grown in the presence of 2 μM NE is also attracted to NE. Growth with NE induces transcription of genes encoding the tyramine oxidase, TynA, and the aromatic aldehyde dehydrogenase, FeaB, whose respective activities can, in principle, convert NE to 3,4-dihydroxymandelic acid (DHMA). Our results indicate that the apparent attractant response to NE is in fact chemotaxis to DHMA, which was found to be a strong attractant for E. coli. Only strains of E. coli K-12 that produce TynA and FeaB exhibited an attractant response to NE. We demonstrate that DHMA is sensed by the serine chemoreceptor Tsr and that the chemotaxis response requires an intact serine-binding site. The threshold concentration for detection is ≤5 nM DHMA, and the response is inhibited at DHMA concentrations above 50 μM. Cells producing a heterodimeric Tsr receptor containing only one functional serine-binding site still respond like the wild type to low concentrations of DHMA, but their response persists at higher concentrations. We propose that chemotaxis to DHMA generated from NE by bacteria that have already colonized the intestinal epithelium may recruit E. coli and other enteric bacteria that possess a Tsr-like receptor to preferred sites of infection.
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA.
authors.forename: Sasikiran
authors.initials: S
authors.lastname: Pasupuleti
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA.
authors.forename: Nitesh
authors.initials: N
authors.lastname: Sule
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA.
authors.forename: William B
authors.initials: WB
authors.lastname: Cohn
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA.
authors.forename: Duncan S
authors.initials: DS
authors.lastname: MacKenzie
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA arulj@tamu.edu mike@bio.tamu.edu.
authors.forename: Arul
authors.initials: A
authors.lastname: Jayaraman
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA arulj@tamu.edu mike@bio.tamu.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Manson
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D001426:Bacterial Proteins / Q000378:metabolism; D002633:Chemotaxis; D048168:Escherichia coli K12 / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D020869:Gene Expression Profiling; D008333:Mandelic Acids / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008995:Monoamine Oxidase / Q000096:biosynthesis / Q000235:genetics; D009638:Norepinephrine / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008333:Mandelic Acids; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607604:tsr protein, E coli; C000989:3,4-dihydroxymandelic acid; D000445:Aldehyde Oxidoreductases; C053855:phenylacetaldehyde dehydrogenase; D008995:Monoamine Oxidase; C585158:TynA protein, E coli; D009638:Norepinephrine