title: Analysis of the capsule biosynthetic locus of Mannheimia (Pasteurella) haemolytica A1 and proposal of a nomenclature system.
abstract: A 16-kbp DNA region that contains genes involved in the biosynthesis of the capsule of Mannheimia (Pasteurella) haemolytica A1 has been characterized. The gene cluster can be divided into three regions like those of the typical group II capsule biosynthetic clusters in gram-negative bacteria. Region 1 contains four genes (wzt, wzm, wzf, and wza) which code for an ATP-binding cassette transport apparatus for the secretion of the capsule materials across the membranes. The M. haemolytica A1 wzt and wzm genes were able to complement Escherichia coli kpsT and kpsM mutants, respectively. Further, the ATP binding activity of Wzt was demonstrated by its affinity for ATP-agarose, and the lipoprotein nature of Wza was supported by [(3)H]palmitate labeling. Region 2 contains six genes; four genes (orf1/2/3/4) code for unique functions for which no homologues have been identified to date. The remaining two genes (nmaA and nmaB) code for homologues of UDP-N-acetylglucosamine-2-epimerase and UDP-N-acetylmannosamine dehydrogenase, respectively. These two proteins are highly homologous to the E. coli WecB and WecC proteins (formerly known as RffE and RffD), which are involved in the biosynthesis of enterobacterial common antigen (ECA). Complementation of an E. coli rffE/D mutant with the M. haemolytica A1 nmaA/B genes resulted in the restoration of ECA biosynthesis. Region 3 contains two genes (wbrA and wbrB) which are suggested to be involved in the phospholipid modification of capsular materials.
authors.affiliation: Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. RLO@micro.uoguelph.ca
authors.forename: R Y
authors.initials: RY
authors.lastname: Lo
authors.forename: L J
authors.initials: LJ
authors.lastname: McKerral
authors.forename: T L
authors.initials: TL
authors.lastname: Hills
authors.forename: M
authors.initials: M
authors.lastname: Kostrzynska
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology; D016667:Bacterial Capsules / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002237:Carbohydrate Dehydrogenases / Q000235:genetics; D002238:Carbohydrate Epimerases / Q000235:genetics; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005807:Genes, Overlapping; D016978:Mannheimia haemolytica / Q000145:classification / Q000235:genetics*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D009626:Terminology as Topic
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C108433:Wzt protein, bacteria; C068104:kpsM protein, E coli; C068103:kpsT protein, E coli; D002237:Carbohydrate Dehydrogenases; C023228:UDP-N-acetylmannosamine dehydrogenase; D002238:Carbohydrate Epimerases; C100033:UDP acetylglucosamine-2-epimerase; C083982:wecB protein, E coli