The AmiC/NlpD pathway dominates peptidoglycan breakdown in Neisseria meningitidisand affects cell separation, NOD1 agonist production, and infection

BioRxiv : the Preprint Server for Biology
J. M. ChanJoseph P Dillard

Abstract

The human-restricted pathogen Neisseria meningitidis, which is best known for causing invasive meningococcal disease, has a nonpathogenic lifestyle as an asymptomatic colonizer of the human naso- and oropharyngeal space. N. meningitidis releases small peptidoglycan (PG) fragments during growth. It was demonstrated previously that N. meningitidis releases low levels of tripeptide PG monomer, which is an inflammatory molecule recognized by the human intracellular innate immune receptor NOD1. In this present study, we demonstrated that N. meningitidis released more PG-derived peptides compared to PG monomers. Using a reporter cell line overexpressing human NOD1, we showed that N. meningitidis activates NOD1 using PG-derived peptides. Generation of such peptides required the presence of the periplasmic N- acetylmuramyl-L-alanine amidase AmiC, and the outer membrane lipoprotein, NlpD. AmiC and NlpD were found to function in cell separation, and mutation of either amiC or nlpD resulted in large clumps of unseparated N. meningitidis cells instead of the characteristic diplococci. Using stochastic optical reconstruction microscopy, we demonstrated that FLAG epitope-tagged NlpD localized to the septum, while similarly-tagged AmiC was fo...Continue Reading

Methods Mentioned

BETA
electron microscopy
size-exclusion chromatography
PCR
transmission electron microscopy

Software Mentioned

Elements AR
NIS
STORM
FIJI

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