Mutational analysis of fructose-1,6-bisphosphate aldolase of Neisseria meningitidis serogroup B

Abstract

Fructose-1,6-bisphosphate aldolase (FBA) is a classical cytoplasmic glycolytic enzyme which, despite lacking a predicted signal peptide, has been demonstrated to be expressed and transported to the surface of numerous Gram-positive bacteria and shown to interact with host molecules and perform non-glycolytic biological functions. Genome-based studies have also demonstrated that the glycolytic pathway appears to be non-functional in the meningococcus due to absence of phosphofructokinase, one of the important enzymes in this pathway. This study aimed to investigate whether the FBA, a so-called housekeeping enzyme, is required for maximal in vitro growth of N. meningitidis. An FBA knock-out mutant was created in N. meningitidis using an inverse polymerase chain reaction (PCR) and allelic exchange methodology. Phenotypic analysis of FBA-deficient mutant strains such as growth profiling experiments showed that the FBA-deficient mutant grew at the same rate (in broth culture and on solid media) as the wild-type strain, suggesting that FBA is not required for optimal growth of N. meningitidis under the in vitro conditions tested. No differences in either colony or bacterial cell morphology (using light microscopy) were observed. In summary, despite being a central enzyme in the glycolytic cycle, FBA is not required for in vitro growth of N. meningitidis.

Key words: Neisseria meningitidis, aldolase, mutagenesis, growth kinetics, glycolytic cycle.