TAILIEUCHUNG - Báo cáo Y học: GNA33 from Neisseria meningitidis serogroup B encodes a membrane-bound lytic transglycosylase (MltA)

In a previous study, we used the genome of serogroup B Meningococcus to identify novel vaccine candidates. One of these molecules, GNA33, is well conserved among Meningococcus B strains, other Meningococcus serogroups and Gonococcus and induces bactericidal antibodies as a result of being a mimetic antigen of the PorA epitope . GNA33 encodes a 48-kDa lipoprotein that is identical with membrane-bound lytic transglycosylase A (MltA) from Escherichia coli. In this study, we expressed GNA33, | Eur. J. Biochem. 269 3722-3731 2002 FEBS 2002 doi GNA33 from Neisseria meningitidis serogroup B encodes a membrane-bound lytic transglycosylase MltA Gary T. Jennings1 Silvana Savino1 Elisa Marchetti1 Beatrice Arico1 Thomas Kast2 Lucia Baldi1 Astrid Ursinus2 Joachim-Volker Holtje2 Robert A. Nicholas3 Rino Rappuoli1 and Guido Grandi1 . Chiron . Siena Italy 2Max Planck Institute fur Entwicklungsbiologie Abteilung Biochemie Tubingen Germany 3Department of Pharmacology University of North Carolina at Chapel Hill NC USA In a previous study we used the genome of serogroup B Meningococcus to identify novel vaccine candidates. One of these molecules GNA33 is well conserved among Meningococcus B strains other Meningococcus serogroups and Gonococcus and induces bactericidal antibodies as a result of being a mimetic antigen of the PorA epitope . GNA33 encodes a 48-kDa lipoprotein that is identical with membrane-bound lytic transglycosylase A MltA from Escherichia coli. In this study we expressed GNA33 . Meningococcus MltA as a lipoprotein in E. coli. The lipoprotein nature of recombinant MltA was demonstrated by incorporation of 3H palmitate. MltA lipoprotein was purified to homogeneity from E. coli membranes by cationexchange chromatography. Muramidase activity was con firmed when MltA was shown to degrade insoluble murein sacculi and unsubstituted glycan strands. HPLC analysis demonstrated the formation of 1 6-anhydrodisaccharide tripeptide and tetrapeptide reaction products confirming that the protein is a lytic transglycosylase. Optimal muramidase activity was observed at pH and 37 C and enhanced by Mg2 Mn2 and Ca2 . The addition of Ni2 and EDTA had no significant effect on activity whereas Zn2 inhibited activity. Triton X-100 stimulated activity . Affinity chromatography indicated that MltA interacts with penicillin-binding protein 2 from Meningococcus B and like MltA from E. coli may form part of a .

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