Molecular characterization of group A Streptococcus maltodextrin catabolism and its role in pharyngitis

Samuel Shelburne, David B. Keith, Michael T. Davenport, Nicola Horstmann, Richard G. Brennan, James M. Musser

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


We previously demonstrated that the cell-surface lipoprotein MalE contributes to GAS maltose/maltodextrin utilization, but MalE inactivation does not completely abrogate GAS catabolism of maltose or maltotriose. Using a genome-wide approach, we identified the GAS phosphotransferase system (PTS) responsible for non-MalE maltose/maltotriose transport. This PTS is encoded by an open reading frame (M5005_spy1692) previously annotated as ptsG based on homology with the glucose PTS in Bacillus subtilis. Genetic inactivation of M5005_spy1692 significantly reduced transport rates of radiolabelled maltose and maltotriose, but not glucose, leading us to propose its reannotation as malT for maltose transporter. The ΔmalT, ΔmalE and ΔmalE:malT strains were significantly attenuated in their growth in human saliva and in their ability to catabolize α-glucans digested by purified human salivary α-amylase. Compared with wild-type, the three isogenic mutant strains were significantly impaired in their ability to colonize the mouse oropharynx. Finally, we discovered that the transcript levels of maltodextrin utilization genes are regulated by competitive binding of the maltose repressor MalR and catabolite control protein A. These data provide novel insights into regulation of the GAS maltodextrin genes and their role in GAS host-pathogen interaction, thereby increasing the understanding of links between nutrient acquisition and virulence in common human pathogens.

Original languageEnglish (US)
Pages (from-to)436-452
Number of pages17
JournalMolecular Microbiology
Issue number2
StatePublished - Jul 2008

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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