Abstract Number: PB0425
Meeting: ISTH 2021 Congress
Background: Group A Streptococcus (GAS) is a human specific pathogen that conscripts the fibrinolytic system to increase its survival and dissemination in the body. In skin-trophic strain AP53 this disruption requires cell wall-anchored plasminogen (hPg)-binding GAS M-protein (PAM) that is anchored via the transpeptidase, sortase A (srtA). Deletion of srtA results in localization of PAM to the cell membrane and the supernatant, a reduction of whole cell hPg binding and activation, and disruption of surface properties. The degree to which membrane-bound PAM in the absence of srtA in GAS strain AP53 is able to bind hPg for activation, and whether changes to other cell surface properties are due to protein localization or transcription, have not been established.
Aims: To further understand the role of srtA in determining cell surface properties and ability to bind hPg for activation in GAS strain AP53.
Methods: An AP53/ΔsrtA mutant was generated by routine techniques. An isogenic complemented strain and a Δpam strain were also generated for comparison. Digestion with PlyC and ultracentrifugation were used to isolate cell fractions. Spectrophotometry was used to quantify bacterial capsule and hydrophobicity. hPg activation assays were performed using a colorimetric reporter. Quantitative RT-PCR was performed to compare transcriptional changes.
Results: Membrane fractions from AP53/ΔsrtA, but not the wild type or complement, activated hPg. In AP53/ΔsrtA, transcription of PAM was unchanged. AP53/ΔsrtA had lower hydrophobicity than wild type but no change in the amount of capsule.
Conclusions: Our data support the hypothesis that PAM retained in the cell membrane retains its ability to bind hPg and is responsible for whole cell hPg binding and activation. Additionally, lack of changes in the amount of capsule and in transcription suggest that observed changes in hydrophobicity and hPg binding and activation when srtA is deleted are due to disruption of PAM surface anchoring rather than changes in transcription.
To cite this abstract in AMA style:Russo B, Ploplis V, Castellino F. Changes in Plasminogen Binding and Cell Surface Properties in Streptococcus pyogenes in the Absence of Sortase A Are Due to Disruptions in Localization of M-protein [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/changes-in-plasminogen-binding-and-cell-surface-properties-in-streptococcus-pyogenes-in-the-absence-of-sortase-a-are-due-to-disruptions-in-localization-of-m-protein/. Accessed May 16, 2022.
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