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Updated: Mar 9, 2026
Label-Free Quantitative Proteomics Workflow for Discovery-Driven Host-Pathogen Interactions
Published on: October 20, 2020
Label-Free Quantitative Proteomic Analysis of Harmless and Pathogenic Strains of Infectious Microalgae, Prototheca
Jayaseelan Murugaiyan1, Murat Eravci2, Christoph Weise3
1Institute of Animal Hygiene and Environmental Health, Centre for Infectious Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany. jayaseelan.murugaiyan@fu-berlin.de.
Abstract:
Microalgae of the genus Prototheca (P.) spp are associated with rare algal infections of invertebrates termed protothecosis. Among the seven generally accepted species, P. zopfii genotype 2 (GT2) is associated with a severe form of bovine mastitis while P. blaschkeae causes the mild and sub-clinical form of mastitis. The reason behind the infectious nature of P. zopfii GT2, while genotype 1 (GT1) remains non-infectious, is not known. Therefore, in the present study we investigated the protein expression level difference between the genotypes of P. zopfii and P. blaschkeae. Cells were cultured to the mid-exponential phase, harvested, and processed for LC-MS analysis. Peptide data was acquired on an LTQ Orbitrap Velos, raw spectra were quantitatively analyzed with MaxQuant software and matching with the reference database of Chlorella variabilis and Auxenochlorella protothecoides resulted in the identification of 226 proteins. Comparison of an environmental strain with infectious strains resulted in the identification of 51 differentially expressed proteins related to carbohydrate metabolism, energy production and protein translation. The expression level of Hsp70 proteins and their role in the infectious process is worth further investigation. All mass spectrometry data are available via ProteomeXchange with identifier PXD005305.
Insights
Infectious Prototheca zopfii (GT2) differs from non-infectious strains and Prototheca blaschkeae in protein expression. This study identified 51 differentially expressed proteins, offering insights into algal infection mechanisms.
Area of Science:
- Microbiology
- Proteomics
- Molecular Biology
Background:
- Prototheca species are algae causing rare infections (protothecosis).
- Prototheca zopfii genotype 2 (GT2) causes severe bovine mastitis, while P. blaschkeae causes mild forms.
- The molecular basis for the differing infectiousness of P. zopfii genotypes (GT1 vs. GT2) is unknown.
Purpose of the Study:
- To investigate differences in protein expression between infectious and non-infectious Prototheca genotypes.
- To compare protein profiles of P. zopfii GT2 and P. blaschkeae.
Main Methods:
- Microalgal cultures were grown to mid-exponential phase.
- Proteins were extracted and analyzed using Liquid Chromatography-Mass Spectrometry (LC-MS).
- Quantitative analysis was performed using MaxQuant software against reference databases.
Main Results:
- 226 proteins were identified in total.
- 51 proteins were differentially expressed between infectious and environmental strains.
- Key differences were observed in proteins related to carbohydrate metabolism, energy production, and translation.
Conclusions:
- Protein expression profiles differ significantly between Prototheca genotypes with varying infectious potential.
- Differentially expressed proteins, particularly Hsp70, warrant further investigation into their role in protothecosis.
- This study provides a foundation for understanding the molecular mechanisms of Prototheca infections.
