title: Structural enzymology of Helicobacter pylori methylthioadenosine nucleosidase in the futalosine pathway.
abstract: The recently discovered futalosine pathway is a promising target for the development of new antibiotics. The enzymes involved in this pathway are crucial for the biosynthesis of the essential prokaryotic respiratory compound menaquinone, and as the pathway is limited to few bacterial species such as the gastric pathogen Helicobacter pylori it is a potential target for specific antibiotics. In this report, the crystal structure of an H. pylori methylthioadenosine nucleosidase (MTAN; an enzyme with broad specificity and activity towards 6-amino-6-deoxyfutalosine), which is involved in the second step of menaquinone biosynthesis, has been elucidated at a resolution of 1.76 Å and refined with R factors of Rwork = 17% and Rfree = 21%. Activity studies on the wild type and active-site mutants show that the hydrolysis of 6-amino-6-deoxyfutalosine follows a mechanism similar to that of Escherichia coli MTAN. Further evidence for this mode of action is supplied by the crystal structures of active-site mutants. Through the use of reaction intermediates, the structures give additional evidence for the previously proposed nucleosidase mechanism. These structures and the confirmed reaction mechanism will provide a structural basis for the design of new inhibitors targeting the futalosine pathway.
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England.
authors.forename: Robbert Q
authors.initials: RQ
authors.lastname: Kim
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Offen
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England.
authors.forename: Gideon J
authors.initials: GJ
authors.lastname: Davies
authors.affiliation: School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Stubbs
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D016480:Helicobacter pylori / Q000201:enzymology* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009705:Nucleosides / Q000378:metabolism*; D011683:Purine-Nucleoside Phosphorylase / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D009705:Nucleosides; C122040:futalosine; D011683:Purine-Nucleoside Phosphorylase; C021784:5'-methylthioadenosine phosphorylase
keywords: Helicobacter pylori; futalosine pathway; hydrolases