title: The structural basis of chain length control in Rv1086.
abstract: In Mycobacterium tuberculosis, two related Z-prenyl diphosphate synthases, E,Z-farnesyl diphosphate synthase (Rv1086) and decaprenyl diphosphate synthase (Rv2361c), work in series to synthesize decaprenyl phosphate (C(50)) from isopentenyl diphosphate and E-geranyl diphosphate. Decaprenyl phosphate plays a central role in the biosynthesis of essential mycobacterial cell wall components, such as the mycolyl-arabinogalactan-peptidoglycan complex and lipoarabinomannan; thus, its synthesis has attracted considerable interest as a potential therapeutic target. Rv1086 is a unique prenyl diphosphate synthase in that it adds only one isoprene unit to geranyl diphosphate, generating the 15-carbon product (E,Z-farnesyl diphosphate). Rv2361c then adds a further seven isoprene units to E,Z-farnesyl diphosphate in a processive manner to generate the 50-carbon prenyl diphosphate, which is then dephosphorylated to generate a carrier for activated sugars. The molecular basis for chain-length discrimination by Rv1086 during synthesis is unknown. We also report the structure of apo Rv1086 with citronellyl diphosphate bound and with the product mimic E,E-farnesyl diphosphate bound. We report the structures of Rv2361c in the apo form, with isopentenyl diphosphate bound and with a substrate analogue, citronellyl diphosphate. The structures confirm the enzymes are very closely related. Detailed comparison reveals structural differences that account for chain-length control in Rv1086. We have tested this hypothesis and have identified a double mutant of Rv1086 that makes a range of longer lipid chains.
authors.affiliation: Centre for Biomolecular Science, The University, St. Andrews, Scotland KY16 9RH, UK.
authors.forename: Wenjian
authors.initials: W
authors.lastname: Wang
authors.forename: Changjiang
authors.initials: C
authors.lastname: Dong
authors.forename: Michael
authors.initials: M
authors.lastname: McNeil
authors.forename: Devinder
authors.initials: D
authors.lastname: Kaur
authors.forename: Sebabrata
authors.initials: S
authors.lastname: Mahapatra
authors.forename: Dean C
authors.initials: DC
authors.lastname: Crick
authors.forename: James H
authors.initials: JH
authors.lastname: Naismith
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D019883:Alkyl and Aryl Transferases; C412569:Rv1086 protein, Mycobacterium tuberculosis