title: Identification of an extremely thermostable enzyme with dual sugar-1-phosphate nucleotidylyltransferase activities from an acidothermophilic archaeon, Sulfolobus tokodaii strain 7.
abstract: L-rhamnose is an essential component of the cell wall and plays roles in mediating virulence and adhesion to host tissues in many microorganisms. Glucose-1-phosphate thymidylyltransferase (RmlA, EC 2.7.7.24) catalyzes the first reaction of the four-step pathway of L-rhamnose biosynthesis, producing dTDP-D-glucose from dTTP and glucose-1-phosphate. Three RmlA homologues of varying size have been identified in the genome of a thermophilic archaeon, Sulfolobus tokodaii strain 7. In this study, we report the heterologous expression of the largest homologue (a 401 residue-long ST0452 protein) and characterization of its thermostable activity. RmlA enzymatic activity of this protein was detected from 65 to 100 degrees C, with a half-life of 60 min at 95 degrees C and 180 min at 80 degrees C. Analysis of a deletion mutant lacking the 170-residue C-terminal domain indicated that this region has an important role in the thermostability and activity of the protein. Analyses of substrate specificity indicated that the enzymatic activity of the full-length protein is capable of utilizing alpha-D-glucose-1-phosphate and N-acetyl-D-glucosamine-1-phosphate but not alpha-D-glucosamine-1-phosphate. However, the protein is capable of utilizing all four deoxyribonucleoside triphosphates and UTP. Thus, the ST0452 protein is an enzyme containing both glucose-1-phosphate thymidylyltransferase and N-acetyl-D-glucosamine-1-phosphate uridylyltransferase activities. This is the first report of a thermostable enzyme with dual sugar-1-phosphate nucleotidylyltransferase activities.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Zilian
authors.initials: Z
authors.lastname: Zhang
authors.forename: Masanari
authors.initials: M
authors.lastname: Tsujimura
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Akutsu
authors.forename: Mayumi
authors.initials: M
authors.lastname: Sasaki
authors.forename: Hideji
authors.initials: H
authors.lastname: Tajima
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kawarabayasi
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D004795:Enzyme Stability; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D016944:Sulfolobus / Q000201:enzymology*; D013816:Thermodynamics
chemical_list: D019843:Archaeal Proteins; D017931:DNA Primers; D011994:Recombinant Proteins; D009713:Nucleotidyltransferases