Contribution of genes from the capsule gene complex (cps) to lipooligosaccharide biosynthesis and serum resistance in Neisseria meningitidis.
Within the capsule gene complex (cps) of Neisseria meningitidis B a 5.5 kb DNA fragment encodes proteins with strong homologies to enzymes of the lipopolysaccharide biosynthetic pathway of Salmonella typhimurium and Escherichia coli, GalE, RfbB, RfbC and RfbD. A meningococcal galE mutant expressed a truncated lipooligosaccharide (LOS), which terminated at the glucose residue between inner and outer core, and a second galE gene present outside the cps cluster was found to be transcriptionally and functionally inactive and, thus, unable to complement this defect. Because of the defect in the outer core, the LOS of the galE-defective meningococcal mutant was not sialylated. In contrast, carbohydrate analysis of the LOS of an rfb-defective meningococcal mutant revealed no difference from the LOS of the wild-type strain, suggesting that the rfb genes are inactive. This was supported by Northern blot analysis, which showed that expression of the rfb gene products was transcriptionally regulated. The inability of the meningococcal galE mutant, which cannot sialylate the LOS, allowed us to investigate the significance of LOS sialylation in relation to the presence of the polysialic acid capsule. Sialylated LOS, but not the polysialic acid capsule, is necessary to confer complete serum resistance on the meningococcus by inhibition of the alternative complement pathway.
Institut für Medizinische Mikrobiologie, Medizinische Hochschule Hannover, Germany.
S
S
Hammerschmidt
C
C
Birkholz
U
U
Zähringer
B D
BD
Robertson
J
J
van Putten
O
O
Ebeling
M
M
Frosch
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002238:Carbohydrate Epimerases / Q000235:genetics* / Q000378:metabolism; D002240:Carbohydrate Sequence; D003170:Complement Pathway, Alternative; D003165:Complement System Proteins / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000235:genetics; D005798:Genes, Bacterial; D006836:Hydro-Lyases / Q000235:genetics* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism*; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid; D009345:Neisseria meningitidis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012794:Sialic Acids / Q000502:physiology; D013045:Species Specificity; D014534:UDPglucose 4-Epimerase; D002237:Carbohydrate Dehydrogenases
D001426:Bacterial Proteins; D002238:Carbohydrate Epimerases; D003165:Complement System Proteins; D006836:Hydro-Lyases; D008070:Lipopolysaccharides; D019158:N-Acetylneuraminic Acid; D012794:Sialic Acids; D014534:UDPglucose 4-Epimerase; C022771:dTDPglucose 4,6-dehydratase; C088100:TDP-deoxyglucose epimerase; C020092:dTDP-4-ketorhamnose 3,5-epimerase; D002237:Carbohydrate Dehydrogenases; C020551:galactose epimerase