Mutations of the Listeria monocytogenes Peptidoglycan<i>N</i>-Deacetylase and<i>O</i>-Acetylase Result in Enhanced Lysozyme Sensitivity, Bacteriolysis, and Hyperinduction of Innate Immune Pathways

Rae, Chris S.; Geissler, Aimee; Adamson, Paul C; Portnoy, Daniel A.

doi:10.1128/iai.00077-11

Cited by 86 publications

(106 citation statements)

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“…1B and C), confirming that all of the mutants identified were significantly more susceptible to lysozyme than WT L. monocytogenes. The screening results were validated by the iden-tification of mutations of pgdA and prsA2, both of which are required for lysozyme resistance in L. monocytogenes (10,26). Insertions in oatA were not identified in the screen; however, this was not surprising, as the oatA phenotype is significant only when paired with ⌬pgdA ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…For lists of all of the strains and primers used in this study, see Tables S2 and S3 in the supplemental material, respectively. Transductions were performed by using U153 phage as previously described (18). Briefly, 10 7 phage were grown in the donor strain, incubated with 10 8 recipient bacteria, and selected for on BHI-erythromycin plates. For construction of the pgdA pbpX rli31 triple mutant, the rli31:: Tn917 transposon was transduced into ⌬pgdA pbpX::Tn and selected for on BHI-chloramphenicol plates.…”

Section: Methodsmentioning

confidence: 99%

“…PgdA deacetylates the amino group of NAG, while OatA O-acetylates NAM, converting the sugar backbone into a poor lysozyme substrate (7,8). pgdA mutants of Streptococcus pneumoniae and oatA mutants of Staphylococcus aureus are lysozyme sensitive, and in each case, lysozyme-sensitive mutants are attenuated in animal models of infection (7)(8)(9)(10).…”

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confidence: 99%

“…Indeed, pgdA oatA double mutants are extremely lysozyme sensitive and more than 1,000-fold less virulent in mice (10). In vitro, pgdA oatA double mutants show increased killing upon phagocytosis by macrophages and undergo bacteriolysis in the macrophage cytosol, which leads to induction of macrophage cell death by pyroptosis (10).…”

mentioning

confidence: 99%

“…Both PgdA and OatA contribute to lysozyme resistance in L. monocytogenes, and pgdA mutants are attenuated during oral and intravenous (i.v.) infections of mice (9,10,12). Indeed, pgdA oatA double mutants are extremely lysozyme sensitive and more than 1,000-fold less virulent in mice (10).…”

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confidence: 99%

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Listeria monocytogenes Is Resistant to Lysozyme through the Regulation, Not the Acquisition, of Cell Wall-Modifying Enzymes

et al. 2014

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Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is highly resistant to lysozyme, a ubiquitous enzyme of the innate immune system that degrades cell wall peptidoglycan. Two peptidoglycan-modifying enzymes, PgdA and OatA, confer lysozyme resistance on L. monocytogenes; however, these enzymes are also conserved among lysozyme-sensitive nonpathogens. We sought to identify additional factors responsible for lysozyme resistance in L. monocytogenes. A forward genetic screen for lysozyme-sensitive mutants led to the identification of 174 transposon insertion mutations that mapped to 13 individual genes. Four mutants were killed exclusively by lysozyme and not other cell wall-targeting molecules, including the peptidoglycan deacetylase encoded by pgdA, the putative carboxypeptidase encoded by pbpX, the orphan response regulator encoded by degU, and the highly abundant noncoding RNA encoded by rli31. Both degU and rli31 mutants had reduced expression of pbpX and pgdA, yet DegU and Rli31 did not regulate each other. Since pbpX and pgdA are also present in lysozyme-sensitive bacteria, this suggested that the acquisition of novel enzymes was not responsible for lysozyme resistance, but rather, the regulation of conserved enzymes by DegU and Rli31 conferred high lysozyme resistance. Each lysozyme-sensitive mutant exhibited attenuated virulence in mice, and a time course of infection revealed that the most lysozyme-sensitive strain was killed within 30 min of intravenous infection, a phenotype that was recapitulated in purified blood. Collectively, these data indicate that the genes required for lysozyme resistance are highly upregulated determinants of L. monocytogenes pathogenesis that are required for avoiding the enzymatic activity of lysozyme in the blood. Lysozyme is a ubiquitous bactericidal enzyme found in the blood, bodily secretions, and phagocytic cells of all animals (1-3). Lysozyme degrades the bacterial cell wall by hydrolyzing the ␤1-4 linkage between the N-acetylglucosamine (NAG) and Nacetylmuramic acid (NAM) residues that comprise the peptidoglycan backbone, often resulting in bacteriolysis (4). Not surprisingly, many pathogens have evolved mechanisms of lysozyme resistance (5, 6). The best-characterized mechanisms of lysozyme resistance involve the acetylation state of the peptidoglycan, catalyzed by the deacetylase PgdA and/or the acetyltransferase OatA. PgdA deacetylates the amino group of NAG, while OatA O-acetylates NAM, converting the sugar backbone into a poor lysozyme substrate (7,8). pgdA mutants of Streptococcus pneumoniae and oatA mutants of Staphylococcus aureus are lysozyme sensitive, and in each case, lysozyme-sensitive mutants are attenuated in animal models of infection (7-10).Listeria monocytogenes is a facultative intracellular pathogen of animals and humans that causes severe disease in pregnant women and immunocompromised individuals (11). Both PgdA and OatA contribute to lysozyme resistance in L. monocytogenes, and pgdA mutants are attenuated during oral a...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Listeria monocytogenes Is Resistant to Lysozyme through the Regulation, Not the Acquisition, of Cell Wall-Modifying Enzymes

et al. 2014

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Listeria innocua isolated from diseased ruminants harbour minor virulence genes of L. monocytogenes

Matto¹,

D’Alessandro

Mota

et al. 2022

Veterinary Medicine & Sci

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Listeriosis is one of the most common nervous diseases in ruminants, and is caused almost exclusively by the Gram-positive bacterium, Listeria monocytogenes. However, there are few reports of listeriosis associated with L. innocua, which is genetically closely related to L. monocytogenes, but considered non-pathogenic. In this work, we report two cases of suppurative meningoencephalitis in apparently previously healthy ruminants from different farms, in which two strains of L. innocua were recovered. The whole genomes from both isolates were sequenced, allowing phylogenetic analyses to be performed, which indicated that the two strains were very closely related. Virulence determinants were searched, especially genes coding for the main L. monocytogenes virulence factors which have been previously described in L. innocua. Surprisingly, the two isolates do not possess such virulence determinants. Instead, both strains carried a set of genes that encode for other virulence factors of the genus Listeria detected using the Virulence Factor Database (VFDB): iap (division and invasion of host cells), lpeA (entry into non-professional phagocytes cells), fbpA (multifunctional virulence factor, including adherence to host cells), lspA (surface protein anchoring), lap (adhesion to enterocytes and trans epithelial translocation), pdgA (resistance to lysozyme), oatA (resistance to different antimicrobial compounds and also required for growth inside macrophages), lplA1 (use of host-metabolites for in vivo growth), gtcA (catalyses teichoic acid of bacterial wall), prsA2 (cell invasion, vacuole lysis and intracellular growth), clpC, clpE and clpP (survival under several stress conditions). These genes among others detected, could be involved in the ability of L. innocua to produce damage in animal and human hosts. These results highlight the multifactorial profile of Listeria pathogenesis and the need for comprehensive scientific research that address microbiological, environmental and veterinary aspects of listeriosis.

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The Antimicrobial Functions of Macrophages

Flannagan

2014

Macrophages: Biology and Role in the Pathology of Diseases

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Mutations of the Listeria monocytogenes PeptidoglycanN-Deacetylase andO-Acetylase Result in Enhanced Lysozyme Sensitivity, Bacteriolysis, and Hyperinduction of Innate Immune Pathways

Cited by 86 publications

References 71 publications

Listeria monocytogenes Is Resistant to Lysozyme through the Regulation, Not the Acquisition, of Cell Wall-Modifying Enzymes

Listeria monocytogenes Is Resistant to Lysozyme through the Regulation, Not the Acquisition, of Cell Wall-Modifying Enzymes

Listeria innocua isolated from diseased ruminants harbour minor virulence genes of L. monocytogenes

The Antimicrobial Functions of Macrophages

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