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Updated: Jul 18, 2026

Enrichment of Bacterial Lipoproteins and Preparation of N-terminal Lipopeptides for Structural Determination by Mass Spectrometry
Published on: May 21, 2018
Anionic lipids enriched at the ExPortal of Streptococcus pyogenes.
Jason W Rosch1, Fong Fu Hsu, Michael G Caparon
1Department of Molecular Microbiology, Washington University School of Medicine, Box 8230, 660 S. Euclid Ave. no. 8230, St. Louis, MO 63110-1093, USA.
Streptococcus pyogenes ExPortal protein secretion relies on specific anionic phospholipids. This study identifies phosphatidylglycerol enrichment in the ExPortal, crucial for its organization and protein trafficking.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- The ExPortal of Streptococcus pyogenes is a specialized membrane microdomain.
- This microdomain is essential for protein secretion and folding.
Purpose of the Study:
- To investigate the lipid composition of the ExPortal.
- To determine the role of anionic phospholipids in ExPortal organization.
Main Methods:
- Utilized 10-N-nonyl-acridine orange staining to examine lipid distribution.
- Analyzed lipid composition in a cardiolipin-deficient mutant.
Main Results:
- Identified a microdomain enriched with phosphatidylglycerol (an anionic phospholipid) within the ExPortal.
- Observed that this microdomain colocalizes with sites of active protein secretion.
Conclusions:
- The ExPortal is an asymmetrically organized lipid microdomain.
- Enriched anionic phospholipids, particularly phosphatidylglycerol, are critical for ExPortal structure and function in protein trafficking.
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