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Peptide permeases from Streptococcus pneumoniae affect adherence to eucaryotic cells
D R Cundell1, B J Pearce, J Sandros
1Laboratory of Molecular Infectious Diseases, Rockefeller University, New York, New York 10021, USA.
Infection and Immunity
|July 1, 1995
Summary
Streptococcus pneumoniae uses peptide permeases, PlpA and Ami, to adhere to host cells by recognizing specific glycoconjugates. These bacterial proteins are crucial for initial colonization of the lungs and blood vessels.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Streptococcus pneumoniae colonizes the nasopharynx before causing infection.
- Pneumococcal adherence to host cells involves bacterial adhesins interacting with cell surface glycoconjugates.
- Identifying these adhesins is key to understanding pneumococcal pathogenesis.
Purpose of the Study:
- To identify bacterial factors mediating Streptococcus pneumoniae adherence to host cells.
- To investigate the role of exported proteins in pneumococcal colonization of the nasopharynx, lungs, and vasculature.
Main Methods:
- Screening of Streptococcus pneumoniae mutants with defects in exported proteins for adherence to erythrocytes, lung cells (LC), and endothelial cells (EC).
- Assessing adherence to cytokine-activated LC and EC to mimic in vivo conditions.
- Sequence analysis of mutated alleles to identify genes involved in adherence.
Main Results:
- Four independent mutants showed a >50% decrease in adherence to both LC and EC.
- Mutations were identified in the plpA and ami loci, encoding protein-dependent peptide permeases.
- ami mutants failed to recognize GalNAc β1-4Gal receptors, while plpA mutants failed to recognize GalNAc β1-3Gal receptors on resting cells.
Conclusions:
- Peptide permeases (PlpA and Ami) are involved in Streptococcus pneumoniae adherence to epithelial and endothelial cells.
- These proteins may act as adhesins or modulate adhesin expression.
- They play a role in the initial colonization of the lung and vascular endothelium by recognizing specific glycoconjugate receptors.