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Differential deuterolysin expression with a peak at low pH in human pathogenic fungi Trichophyton rubrum and T.
JingJing Chen1, Oliver Blechert2, Shuzhen Xiong1
1Nanchang University, Nanchang 330006, China.
Abstract:
Trichophyton rubrum and T. mentagrophytes are the most common agents of dermatomycosis, a disease affecting millions worldwide. It has been widely recognized that secreted proteases are a key factor for host colonization. Dermatophytes have an unusually high amount of secreted protease, differentially expressed, and influenced by various conditions. This study analyzed the rule and expression of secreted deuterolysin protease of the M35 protein family in these two representative dermatophyte species. All strains secreted protease and could grow on keratin as the sole carbon and nitrogen source. Adding glucose to the keratin medium reduced the growth rate. Deuterolysin genes were most strongly expressed at acid conditions. NPIIc and NPIId expression was significantly higher than the other three deuterolysins. NPIIc had a high expression level in the two T. rubrum strains but a low expression in T. mentagrophytes strains. Both T. mentagrophytes strains had a high NPIId expression at low pH. NPIIc and NPIId deletion in T. rubrum caused a minor reduction in total protease activity, indicating the redundancy of protease in dermatophytes. It was postulated that protease gene enrichment in dermatophytes allows a sophisticated regulation of protease secretion to cope with changing conditions.
Insights
Dermatophytes like Trichophyton rubrum secrete proteases for infection. This study reveals specific deuterolysin protease genes (NPIIc, NPIId) are key, with expression varying by species and pH, suggesting adaptable virulence strategies.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- Dermatomycosis, caused by fungi like Trichophyton rubrum and T. mentagrophytes, affects millions globally.
- Secreted proteases are crucial for dermatophyte colonization and virulence.
- Dermatophytes exhibit a high and differentially expressed repertoire of secreted proteases.
Purpose of the Study:
- To investigate the role and expression of secreted deuterolysin proteases (M35 protein family) in T. rubrum and T. mentagrophytes.
- To understand how environmental conditions influence protease gene expression.
- To assess the contribution of specific deuterolysins to overall protease activity.
Main Methods:
- Culturing dermatophyte strains on keratin as the sole nutrient source.
- Analyzing protease secretion and growth rates under varying conditions (e.g., presence of glucose, pH).
- Quantifying deuterolysin gene expression (NPIIc, NPIId) using molecular techniques.
- Generating gene deletion mutants to assess protease activity.
Main Results:
- All tested strains secreted protease and utilized keratin for growth; glucose addition inhibited growth.
- Deuterolysin genes showed peak expression under acidic conditions, with NPIIc and NPIId being highly expressed.
- NPIIc expression was high in T. rubrum but low in T. mentagrophytes, while NPIId was highly expressed in T. mentagrophytes at low pH.
- Deletion of NPIIc and NPIId in T. rubrum resulted in only a minor decrease in total protease activity.
Conclusions:
- Protease gene redundancy in dermatophytes allows for functional compensation.
- Sophisticated regulation of protease secretion enables dermatophytes to adapt to diverse host environments.
- Deuterolysins, particularly NPIIc and NPIId, play significant but potentially redundant roles in dermatophyte virulence.
