title: Genetic basis for biosynthesis of the (alpha 1-->4)-linked N-acetyl-D-glucosamine 1-phosphate capsule of Neisseria meningitidis serogroup X.
abstract: The genetic basis for biosynthesis of the (alpha1-->4)-linked N-acetyl-D-glucosamine 1-phosphate capsule of Neisseria meningitidis serogroup X was defined. The biosynthesis gene cassette was a approximately 4.2-kb region located between ctrA of the capsule transport operon and galE, which encodes the UDP-glucose-4-epimerase. This location was identical to the locations of the biosynthesis cassettes in other meningococcal serogroups. Three open reading frames unique to meningococcus serogroup X were identified. Deletion-insertion mutation and colony immunoblotting confirmed that these three genes were essential for serogroup X capsule expression, and the genes were designated xcbA, xcbB, and xcbC (serogroup X capsule biosynthesis). Reverse transcriptase PCR indicated that the xcbABC genes form an operon and are cotranscribed divergently from ctrA. XcbA exhibited 52% amino acid similarity to SacB, the putative capsule polymerase of meningococcus serogroup A, suggesting that it plays a role as the serogroup X capsule polymerase. An IS1016 element was found within the intergenic region separating ctrA and xcbA in multiple strains, and this element did not interfere with capsule expression.
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA. ytzeng@emory.edu
authors.forename: Yih-Ling
authors.initials: YL
authors.lastname: Tzeng
authors.forename: Corie
authors.initials: C
authors.lastname: Noble
authors.forename: David S
authors.initials: DS
authors.lastname: Stephens
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D000595:Amino Acid Sequence; D016667:Bacterial Capsules / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001770:Blood Bactericidal Activity; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D009876:Operon; D010710:Phosphates / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012703:Serotyping; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D014534:UDPglucose 4-Epimerase / Q000737:chemistry / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C097706:CtrA protein, Caulobacter; D004268:DNA-Binding Proteins; D010710:Phosphates; D014157:Transcription Factors; D014534:UDPglucose 4-Epimerase; C020551:galactose epimerase; D000117:Acetylglucosamine