A Lytic Transglycosylase of Neisseria gonorrhoeae Is Involved in Peptidoglycan-Derived Cytotoxin Production

Abstract

Neisseria gonorrhoeae releases soluble fragments of peptidoglycan during growth. These molecules are implicated in the pathogenesis of various forms of gonococcal infection. A major peptidoglycan fragment released by gonococci is identical to the tracheal cytotoxin of Bordetella pertussis and has been shown to kill ciliated fallopian tube cells in organ culture. Previous studies indicated that a unique lytic peptidoglycan transglycosylase (AtlA) was responsible for some, but not all, of the peptidoglycan-derived cytotoxin (PGCT) production in certain gonococcal strains. To examine the role of other putative lytic transglycosylases in PGCT production, we made a deletion mutation in a gonococcal gene exhibiting similarity with genes encoding lytic transglycosylases from other bacterial species. The gonococcal mutant was viable and grew normally, but it was less autolytic than the wild-type strain in stationary-phase culture and under nongrowth conditions. The gonococcal mutant was reduced in peptidoglycan turnover, and the profile of the released products showed a reduction in monomeric peptidoglycan. Proportionally more multimeric fragments were released. These results suggest that this gonococcal gene (ltgA) encodes a lytic peptidoglycan transglycosylase and that it is responsible for a significant proportion of the PGCT released by N. gonorrhoeae.

Genome-wide analysis of DNA repeats in Burkholderia cenocepacia J2315 identifies a novel adhesin-like gene unique to epidemic-associated strains of the ET-12 lineage

“…Among the 45 genes, 34 have been previously described as virulence factors in Burkholderia strains or other bacterial pathogenic genera, such as Neisseria, Mycobacterium, Haemophilus and Vibrio. These include genes for phase-variable oligosaccharide structure of lipopolysaccharide (Hughes et al, 1997;Vinion-Dubiel & Goldberg, 2003), siderophore production (Anderson et al, 2004;Visser et al, 2004), multidrugresistant transporters (Wigfield et al, 2002), cable pili , and intra-and extracellular enzymes, such as haemolysin and lytic transglycosylase (Cloud & Dillard, 2002;Takahashi et al, 2004).…”

The amoebae plate test implicates a paralogue of lpxB in the interaction of Legionella pneumophila with Acanthamoeba castellanii

“…While the structure of the toxic product of LcsC remains to be identified, it might either associate with bacteria or be released into the supernatant. Soluble cytotoxic peptidoglycan derivatives have been described for Bordetella pertussis, Neisseria gonorrhoeae, Haemophilus influenzae and other bacteria (Burroughs et al, 1993;Cloud & Dillard, 2002;Cookson et al, 1989;Luker et al, 1993Luker et al, , 1995. For example, the murein-derived tracheal cytotoxin (TCT; N-acetyl-GlcN-1,6-anhydro-N-acetyl-muramyl-LAla-c-D-Glu-meso-diaminopimelyl-D-Ala) from B. pertussis is released by growing bacteria and is sufficient to reproduce the cytopathology observed during whooping cough.…”

Mutation of a Single Lytic Transglycosylase Causes Aberrant Septation and Inhibits Cell Separation of Neisseria gonorrhoeae

“…Effects of ltgC mutation on PG fragment release. To determine if LtgC functions in the production or release of PG monomers, PG from MS11 and KC118 was metabolically labeled with [6-3 H]glucosamine, and released PG fragments were collected and analyzed by size-exclusion chromatography as previously described (2). PG monomer release was not significantly reduced in the ltgC mutant, showing at most a slight decrease (Fig.…”

“…However, soluble PG fragments were released into the medium at a higher rate in the ltgC mutant than in the wild type. PG turnover was measured for the wild-type, ltgC mutant, and complemented strains as described previously (2). After 4 h, only 51.2% Ϯ 4.3% of macromolecular PG remained in KC118.…”

“…Colonies of KC118 appeared slightly smaller on an agar plate, and the mutant did not appear to grow rapidly when inoculated into liquid culture. Gonococci were grown with aeration in gonococcal base liquid medium as previously described (2). When inoculated at equivalent optical densities, both the number of CFU per milliliter (Fig.…”