title: Molecular characterization of phosphorylcholine expression on the lipooligosaccharide of Histophilus somni.
abstract: Histophilus somni (Haemophilus somnus) is an important pathogen of cattle that is responsible for respiratory disease, septicemia, and systemic diseases such as thrombotic meningoencephalitis, myocarditis, and abortion. A variety of virulence factors have been identified in H. somni, including compositional and antigenic variation of the lipooligosaccharide (LOS). Phosphorylcholine (ChoP) has been identified as one of the components of H. somni LOS that undergoes antigenic variation. In this study, five genes (lic1ABCD(Hs) and glpQ) with homology to genes responsible for ChoP expression in Haemophilus influenzae LOS were identified in the H. somni genome. An H. somni open reading frame (ORF) with homology to H. influenzae lic1A (lic1A(Hi)) contained a variable number of tandem repeats (VNTR). However, whereas the tetranucleotide repeat 5'-CAAT-3' is present in lic1A(Hi), the VNTR in H. somni lic1A (lic1A(Hs)) consisted of 5'-AACC-3'. Due to the propensity of VNTR to vary during replication and cause the ORF to shift in and out of frame with the upstream start codon, the VNTR were deleted from lic1A(Hs) to maintain the gene constitutively on. This construct was cloned into Escherichia coli, and functional enzyme assays confirmed that lic1A(Hs) encoded a choline kinase, and that the VNTR were not required for expression of a functional gene product. Variation in the number of VNTR in lic1A(Hs) correlated with antigenic variation of ChoP expression in H. somni strain 124P. However, antigenic variation of ChoP expression in strain 738 predominately occurred through variable extension/truncation of the LOS outer core. These results indicated that the lic1(Hs) genes controlled expression of ChoP on the LOS, but that in H. somni there are two potential mechanisms that account for antigenic variation of ChoP.
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Shaadi F
authors.initials: SF
authors.lastname: Elswaifi
authors.forename: Frank
authors.initials: F
authors.lastname: St Michael
authors.forename: Avula
authors.initials: A
authors.lastname: Sreenivas
authors.forename: Andrew
authors.initials: A
authors.lastname: Cox
authors.forename: George M
authors.initials: GM
authors.lastname: Carman
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Inzana
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D001426:Bacterial Proteins / Q000235:genetics; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D002797:Choline Kinase / Q000235:genetics; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D006190:Haemophilus / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D006192:Haemophilus Infections / Q000662:veterinary; D008070:Lipopolysaccharides / Q000378:metabolism*; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D010767:Phosphorylcholine / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D010767:Phosphorylcholine; D002797:Choline Kinase
references.citation: J Bacteriol. 2004 Nov;186(21):7429-39
references.pmid: 15489455
references.citation: Sci Am. 1999 Jan;280(1):94-9
references.pmid: 9891422
references.citation: Carbohydr Res. 2003 May 23;338(11):1223-8
references.pmid: 12747865
references.citation: Anal Biochem. 1982 Jan 1;119(1):115-9
references.pmid: 6176137
references.citation: Infect Immun. 2000 Aug;68(8):4593-7
references.pmid: 10899860
references.citation: Nature. 1993 Sep 16;365(6443):274-6
references.pmid: 8371783
references.citation: Carbohydr Res. 2004 Feb 25;339(3):529-35
references.pmid: 15013390
references.citation: EMBO J. 2002 Mar 15;21(6):1465-76
references.pmid: 11889052
references.citation: Microb Pathog. 2000 May;28(5):301-12
references.pmid: 10799280
references.citation: Cell. 1989 Nov 17;59(4):657-65
references.pmid: 2479481
references.citation: Electrophoresis. 1999 Mar;20(3):462-5
references.pmid: 10217153
references.citation: J Med Microbiol. 1996 Jan;44(1):35-40
references.pmid: 8544209
references.citation: Nature. 1987 Sep 3-9;329(6134):21
references.pmid: 3041224
references.citation: Infect Immun. 1997 Mar;65(3):943-50
references.pmid: 9038301
references.citation: J Clin Microbiol. 1985 Aug;22(2):192-8
references.pmid: 4031034
references.citation: Clin Microbiol Rev. 2004 Jul;17(3):581-611, table of contents
references.pmid: 15258095
references.citation: Infect Immun. 2000 Jan;68(1):310-9
references.pmid: 10603403
references.citation: Scand J Immunol. 1988 Aug;28(2):129-37
references.pmid: 2457934
references.citation: Mol Microbiol. 1999 Sep;33(5):919-32
references.pmid: 10476027
references.citation: J Biol Chem. 1998 Mar 20;273(12):6844-52
references.pmid: 9506987
references.citation: Methods Enzymol. 1992;209:134-46
references.pmid: 1323026
references.citation: J Exp Med. 1998 Feb 16;187(4):631-40
references.pmid: 9463413
references.citation: Am J Vet Res. 1987 Mar;48(3):366-9
references.pmid: 3565890
references.citation: Carbohydr Res. 2005 Mar 21;340(4):665-72
references.pmid: 15721338
references.citation: Infect Immun. 1997 Nov;65(11):4675-81
references.pmid: 9353049
references.citation: Infect Immun. 1998 Sep;66(9):4263-7
references.pmid: 9712776
references.citation: Mol Microbiol. 2000 Jan;35(1):234-45
references.pmid: 10632893
references.citation: Mol Microbiol. 1991 Jun;5(6):1549-60
references.pmid: 1664907
references.citation: J Biol Chem. 1999 May 21;274(21):14857-66
references.pmid: 10329685
references.citation: Infect Immun. 2002 Sep;70(9):4870-9
references.pmid: 12183531
references.citation: Eur J Biochem. 2000 Jun;267(12):3902-13
references.pmid: 10849010
references.citation: J Bacteriol. 2007 Oct;189(20):7384-91
references.pmid: 17704225
references.citation: Mol Microbiol. 2001 Sep;41(5):1029-36
references.pmid: 11555284
references.citation: Mol Microbiol. 2000 Mar;35(6):1550-9
references.pmid: 10760154
references.citation: Infect Immun. 2001 Mar;69(3):1650-60
references.pmid: 11179340
references.citation: J Microbiol Methods. 2008 Aug;74(2-3):106-9
references.pmid: 18502523
references.citation: Mol Microbiol. 2000 Jul;37(1):13-27
references.pmid: 10931302
references.citation: Microb Pathog. 1997 Dec;23(6):327-33
references.pmid: 9441859
references.citation: Infect Immun. 1997 Oct;65(10):4250-7
references.pmid: 9317034
references.citation: Mol Biol Evol. 1987 May;4(3):203-21
references.pmid: 3328815
references.citation: Eur J Biochem. 1998 Apr 15;253(2):507-16
references.pmid: 9654104
references.citation: Eur J Biochem. 1993 Aug 1;215(3):851-7
references.pmid: 8354290
references.citation: Mol Microbiol. 1996 Apr;20(1):165-74
references.pmid: 8861214
references.citation: Microbiol Mol Biol Rev. 1998 Jun;62(2):275-93
references.pmid: 9618442
references.citation: J Infect Dis. 1983 Sep;148(3):492-9
references.pmid: 6604761
references.citation: Infect Immun. 1992 Jul;60(7):2943-51
references.pmid: 1612761
references.citation: J Clin Microbiol. 2000 Dec;38(12):4412-9
references.pmid: 11101573
references.citation: Mol Microbiol. 2003 Oct;50(2):537-48
references.pmid: 14617177
references.citation: J Mol Biol. 1990 Oct 5;215(3):403-10
references.pmid: 2231712