Characterization of SfPgdA, a Shigella flexneri peptidoglycan deacetylase required for bacterial persistence within polymorphonuclear neutrophils.
Microbes Infect
; 14(7-8): 619-27, 2012 Jul.
Article
in En
| MEDLINE
| ID: mdl-22307019
ABSTRACT
Peptidoglycan deacetylases protect the Gram-positive bacteria cell wall from host lysozymes by deacetylating peptidoglycan. Sequence analysis of the genome of Shigella flexneri predicts a putative polysaccharide deacetylase encoded by the plasmidic gene orf185, renamed here SfpgdA. We demonstrated a peptidoglycan deacetylase (PGD) activity with the purified SfPgdA in vitro. To investigate the role SfPgdA in virulence, we constructed a SfpgdA mutant and studied its phenotype in vitro. The mutant showed an increased sensitivity to lysozyme compared to the parental strain. Moreover, the mutant was rapidly killed by polymorphonuclear neutrophils (PMNs). Specific substitution of histidines residues 120 and 125, located within the PGD catalytic domain, by phenylalanine abolished SfPgdA function. SfPgdA expression is controlled by PhoP. Mutation of phoP increases sensitivity to lysozyme compared to the SfpgdA mutant. Here, we confirmed that SfPgdA expression is enhanced under low magnesium concentration and not produced by the phoP mutant. Ectopic expression of SfPgdA in the phoP mutant restored lysozyme resistance and parental bacterial persistence within PMNs. Together our results indicate that PG deacetylation mechanism likely contributes to Shigella persistence by subverting detection by the host immune system.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Acetylesterase
/
Shigella flexneri
/
Dysentery, Bacillary
/
Amidohydrolases
/
Neutrophils
Limits:
Child, preschool
/
Humans
/
Infant
Language:
En
Journal:
Microbes Infect
Journal subject:
ALERGIA E IMUNOLOGIA
/
MICROBIOLOGIA
Year:
2012
Document type:
Article
Affiliation country: