Streptococcus pneumoniae, S. pyogenes and S. agalactiae membrane phospholipid remodelling in response to human serum
Luke R Joyce1, Ziqiang Guan2, Kelli L Palmer1
1Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA.
Abstract:
Streptococcus pneumoniae, S. pyogenes (Group A Streptococcus; GAS) and S. agalactiae (Group B Streptococcus; GBS) are major aetiological agents of diseases in humans. The cellular membrane, a crucial site in host-pathogen interactions, is poorly characterized in streptococci. Moreover, little is known about whether or how environmental conditions influence their lipid compositions. Using normal phase liquid chromatography coupled with electrospray ionization MS, we characterized the phospholipids and glycolipids of S. pneumoniae, GAS and GBS in routine undefined laboratory medium, streptococcal defined medium and, in order to mimic the host environment, defined medium supplemented with human serum. In human serum-supplemented medium, all three streptococcal species synthesize phosphatidylcholine (PC), a zwitterionic phospholipid commonly found in eukaryotes but relatively rare in bacteria. We previously reported that S. pneumoniae utilizes the glycerophosphocholine (GPC) biosynthetic pathway to synthesize PC. Through substrate tracing experiments, we confirm that GAS and GBS scavenge lysoPC, a major metabolite in human serum, thereby using an abbreviated GPC pathway for PC biosynthesis. Furthermore, we found that plasmanyl-PC is uniquely present in the GBS membrane during growth with human serum, suggesting GBS possesses unusual membrane biochemical or biophysical properties. In summary, we report cellular lipid remodelling by the major pathogenic streptococci in response to metabolites present in human serum.
Insights
Pathogenic streptococci like Streptococcus pneumoniae adapt their cell membranes by synthesizing phosphatidylcholine (PC) when exposed to human serum. This lipid remodeling involves scavenging serum metabolites for PC biosynthesis, particularly in Group A and B Streptococcus.
Area of Science:
- Microbiology
- Biochemistry
- Host-Pathogen Interactions
Background:
- Streptococcus pneumoniae, Streptococcus pyogenes (Group A Streptococcus; GAS), and Streptococcus agalactiae (Group B Streptococcus; GBS) are significant human pathogens.
- The cellular membrane's lipid composition in streptococci is poorly understood, especially how environmental factors influence it.
- Host-pathogen interactions heavily involve the cellular membrane, highlighting the need to characterize streptococcal membrane lipids.
Purpose of the Study:
- To characterize the phospholipid and glycolipid profiles of S. pneumoniae, GAS, and GBS under different growth conditions.
- To investigate how human serum influences the lipid composition of these pathogenic streptococci.
- To elucidate the biosynthetic pathways for phosphatidylcholine (PC) synthesis in response to serum components.
Main Methods:
- Lipidomic analysis using normal phase liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS).
- Cultivation of S. pneumoniae, GAS, and GBS in routine undefined medium, defined medium, and defined medium supplemented with human serum.
- Substrate tracing experiments to confirm biosynthetic pathways for PC.
Main Results:
- All three streptococcal species synthesized phosphatidylcholine (PC) when grown in human serum-supplemented medium.
- GAS and GBS were confirmed to scavenge lysophosphatidylcholine (lysoPC) from human serum for PC biosynthesis via an abbreviated glycerophosphocholine (GPC) pathway.
- Plasmanyl-PC was uniquely detected in the GBS membrane during growth in human serum, suggesting distinct membrane properties.
Conclusions:
- Major pathogenic streptococci exhibit significant cellular lipid remodeling in response to human serum metabolites.
- The ability to synthesize PC, a eukaryotic-like lipid, is a key adaptation strategy for these bacteria in a host-like environment.
- Group B Streptococcus (GBS) displays unique membrane lipid characteristics, potentially influencing its pathogenicity or interaction with the host.
More Related Videos
08:25Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling
Published on: April 7, 2015
12:21A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness
Published on: September 28, 2022
Related Concept Videos
01:19Formation of Lipopolysaccharides
01:29Biosynthesis of Lipids
01:35Asymmetric Lipid Bilayer