GNA33 of Neisseria meningitidis Is A Lipoprotein Required for Cell Separation, Membrane Architecture, and Virulence

Università degli Studi di Siena, Siena, Tuscany, Italy
Infection and Immunity (Impact Factor: 3.73). 05/2004; 72(4):1914-9. DOI: 10.1128/IAI.72.4.1914-1919.2004
Source: PubMed


GNA33 is a membrane-bound lipoprotein with murein hydrolase activity that is present in all Neisseria species and well conserved in different meningococcal isolates. The protein shows 33% identity to a lytic transglycolase
(MltA) from Escherichia coli and has been shown to be involved in the degradation of both insoluble murein sacculi and unsubstituted glycan strands. To
study the function of the gene and its role in pathogenesis and virulence, a knockout mutant of a Neisseria meningitidis serogroup B strain was generated. The mutant exhibited retarded growth in vitro. Transmission electron microscopy revealed
that the mutant grows in clusters which are connected by a continuous outer membrane, suggesting a failure in the separation
of daughter cells. Moreover, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of culture supernatant revealed
that the mutant releases several proteins in the medium. The five most abundant proteins, identified by matrix-assisted laser
desorption ionization-time-of-flight mass spectrometry analysis, belong to the outer membrane protein family. Finally, the
mutant showed an attenuated phenotype, since it was not able to cause bacteremia in the infant rat model. We conclude that
GNA33 is a highly conserved lipoprotein which plays an important role in peptidoglycan metabolism, cell separation, membrane
architecture, and virulence.

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