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Signal peptide variation in cyst lectins as a potential marker for pathogenic Acanthamoeba spp
Chih-Ming Tsai1, Wei-Hung Cheng1,2, Wei-Chen Lin3,4
1Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan City, Taiwan.
Background:
Acanthamoeba species are free-living protists widely distributed in natural and artificial environments, including freshwater, soil, and water-associated facilities. Some isolates can cause opportunistic human infections, such as Acanthamoeba keratitis and granulomatous amoebic encephalitis. The life cycle of Acanthamoeba includes an active trophozoite stage and a dormant cyst stage. The cyst is surrounded by a complex double-layered wall composed of cellulose and multiple structural proteins, including cyst wall lectins. While the architecture and molecular composition of the cyst wall have been investigated, inter-isolate sequence variation of cyst wall components remains poorly characterized.
Methods:
We performed a genome-based comparative analysis of 31 previously characterized cyst wall lectins, analyzing the homologous sequence of each lectin across 31 publicly available Acanthamoeba genomes. Isolates were classified as clinical or environmental on the basis of their reported sources. Sequence similarity-based clustering was conducted to identify lectins associated with clinical isolates. For selected genes, sequence features at the 5' region were further examined and experimentally validated by polymerase chain reaction using long-term axenic clinical isolates maintained at National Cheng Kung University Hospital.
Results:
Similarity-based clustering identified eight cyst wall lectins that formed clusters enriched for clinical isolates. Among these, three lectins showed pronounced sequence variation at the 5' region in multiple clinical isolate genomes. Polymerase chain reaction (PCR) validation confirmed that these variations were present in clinical isolates and were not attributable to genome assembly artifacts. Sequence analysis suggested that these variations may affect signal peptide features at the amino terminus of the proteins.
Conclusions:
Our findings reveal previously underexplored sequence diversity in cyst wall lectins across Acanthamoeba isolates. This diversity may contribute to differences in cyst wall architecture between clinical and environmental isolates. These results provide new insight into cyst-associated molecular features that may be linked to pathogenic potential and offer a foundation for future studies on cyst-mediated adaptation and infection.
Insights
Sequence variations in Acanthamoeba cyst wall lectins were identified, with some linked to clinical isolates. This diversity may influence cyst structure and the pathogen's potential.
Area of Science:
- Microbiology
- Molecular Biology
- Genomics
Background:
- Acanthamoeba are ubiquitous protists causing opportunistic infections like keratitis.
- Their life cycle involves trophozoite and cyst stages, with the cyst wall containing proteins like lectins.
- Previous research detailed cyst wall structure but lacked data on inter-isolate sequence variation.
Purpose of the Study:
- To investigate sequence variation in Acanthamoeba cyst wall lectins across different isolates.
- To identify lectins potentially associated with clinical Acanthamoeba isolates.
- To explore the implications of sequence diversity on cyst wall properties and pathogenicity.
Main Methods:
- Genome-based comparative analysis of 31 cyst wall lectins across 31 Acanthamoeba genomes.
- Classification of isolates as clinical or environmental based on source.
- Sequence similarity-based clustering to identify lectin clusters enriched in clinical isolates.
- Experimental validation of 5' region sequence variations using PCR.
Main Results:
- Eight cyst wall lectins formed clusters associated with clinical isolates.
- Three lectins exhibited significant 5' region sequence variation in clinical isolates.
- PCR confirmed these variations were genuine and not assembly artifacts.
- Variations may impact signal peptide features in lectins.
Conclusions:
- Significant sequence diversity exists in Acanthamoeba cyst wall lectins, previously underexplored.
- This diversity may underlie differences in cyst wall architecture between clinical and environmental strains.
- Findings offer insights into cyst-associated molecular features linked to pathogenic potential.
