title: The hydantoin transport protein from Microbacterium liquefaciens.
abstract: The gene hyuP from Microbacterium liquefaciens AJ 3912 with an added His6 tag was cloned into the expression plasmid pTTQ18 in an Escherichia coli host strain. The transformed E. coli showed transport of radioisotope-labeled 5-substituted hydantoins with apparent K(m) values in the micromolar range. This activity exhibited a pH optimum of 6.6 and was inhibited by dinitrophenol, indicating the requirement of energy for the transport system. 5-Indolyl methyl hydantoin and 5-benzyl hydantoin were the preferred substrates, with selectivity for a hydrophobic substituent in position 5 of hydantoin and for the l isomer over the d isomer. Hydantoins with less hydrophobic substituents, cytosine, thiamine, uracil, allantoin, adenine, and guanine, were not effective ligands. The His-tagged hydantoin transport protein was located in the inner membrane fraction, from which it was solubilized and purified and its identity was authenticated.
authors.affiliation: Astbury Centre for Structural Molecular Biology, University of Leeds, West Yorkshire, United Kingdom. shunichi_suzuki@ajinomoto.com
authors.forename: Shun'ichi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Peter J F
authors.initials: PJ
authors.lastname: Henderson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D004140:Dinitrophenols / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D006827:Hydantoins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008835:Micrococcaceae / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004140:Dinitrophenols; D006827:Hydantoins; C067244:5-indolylmethylhydantoin; C031427:5-benzylhydantoin