title: The cloning and DNA sequence of the gene xylE for xylose-proton symport in Escherichia coli K12.
abstract: The gene xylE, coding for xylose-proton symport in Escherichia coli, was cloned and its DNA sequence determined. The cloning strategy utilized lambda placMu insertions and exploited the proximity of xylE to malB. A 2.8-kilobase HincII fragment of cloned DNA restored [14C]xylose transport and xylose-proton symport activities to a xylose transport-negative strain. The xylE gene was identified as a 1473-base pair open reading frame, located 373 base pairs downstream of malG, encoding a hydrophobic protein of Mr 53,607. The amino acid sequence of XylE bore little resemblance to the lactose-proton LacY symporter or melibiose-sodium MelB symporter, but a high degree of homology was found with the arabinose-proton AraE symporter of E. coli and glucose transport proteins of mammals. Structural analyses and comparisons suggest that 12 membrane-spanning segments may occur in the XylE protein.
authors.affiliation: Department of Biochemistry, University of Cambridge, United Kingdom.
authors.forename: E O
authors.initials: EO
authors.lastname: Davis
authors.forename: P J
authors.initials: PJ
authors.lastname: Henderson
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005796:Genes; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D013045:Species Specificity; D027981:Symporters; D014994:Xylose / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D027981:Symporters; C033903:xylE protein, E coli; D014994:Xylose; D004262:DNA Restriction Enzymes