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Contribution of AmyA, an extracellular α-glucan degrading enzyme, to group A streptococcal host–pathogen interaction.
- Source :
-
Molecular Microbiology . Oct2009, Vol. 74 Issue 1, p159-174. 16p. 3 Diagrams, 1 Chart, 5 Graphs. - Publication Year :
- 2009
-
Abstract
- α-Glucans such as starch and glycogen are abundant in the human oropharynx, the main site of group A Streptococcus (GAS) infection. However, the role in pathogenesis of GAS extracellular α-glucan binding and degrading enzymes is unknown. The serotype M1 GAS genome encodes two extracellular proteins putatively involved in α-glucan binding and degradation; pulA encodes a cell wall anchored pullulanase and amyA encodes a freely secreted putative cyclomaltodextrin α-glucanotransferase. Genetic inactivation of amyA, but not pulA, abolished GAS α-glucan degradation. The Δ amyA strain had a slower rate of translocation across human pharyngeal epithelial cells. Consistent with this finding, the Δ amyA strain was less virulent following mouse mucosal challenge. Recombinant AmyA degraded α-glucans into β-cyclomaltodextrins that reduced pharyngeal cell transepithelial resistance, providing a physiologic explanation for the observed transepithelial migration phenotype. Higher amyA transcript levels were present in serotype M1 GAS strains causing invasive infection compared with strains causing pharyngitis. GAS proliferation in a defined α-glucan-containing medium was dependent on the presence of human salivary α-amylase. These data delineate the molecular mechanisms by which α-glucan degradation contributes to GAS host–pathogen interaction, including how GAS uses human salivary α-amylase for its own metabolic benefit. [ABSTRACT FROM AUTHOR]
- Subjects :
- *GLUCANS
*STARCH
*GLYCOGEN
*STREPTOCOCCUS
*PATHOGENIC microorganisms
*ENZYMES
*GENOMES
Subjects
Details
- Language :
- English
- ISSN :
- 0950382X
- Volume :
- 74
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Molecular Microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 44280386
- Full Text :
- https://doi.org/10.1111/j.1365-2958.2009.06858.x