Gene expression and microsecond scale conformational dynamics suggest potential regulatory mechanisms for the expanded subtilase family of <i>T. rubrum</i>

Dermatophytes, such as Trichophyton rubrum, are the primary causative agent for superficial fungal infections worldwide. Recent rise in drug resistant cases of dermatophytes have been observed highlighting the urgent need for new therapeutic targets. In this study, the correlation of expression dynamics of the secreted subtilase family with key in silico-identified sequence and structural features has been investigated. Expression analysis revealed two discrete clusters for the sixteen subtilases (Sub1 to Sub16) of T. rubrum, with distinct temporal expression patterns. Sub8, Sub9, Sub10, Sub12, Sub14 and Sub15 with expression at early stages of growth (day7) formed one distinct subgroup. Sub1, Sub3, Sub4, Sub5 and Sub13, exhibit expression at multiple growth stages, suggesting that members of the expanded subtilase family could be deployed in a coordinated manner to optimize substrate utilization throughout the growth cycle of the fungus. Further, more than eight microseconds of MD simulations were employed to provide cues into unique protease-specific regulatory mechanisms. A flexible regulatory loop was identified in Sub2 that potentially restricts access to larger peptides, making it functionally suitable for smaller peptides. Together, these findings demonstrate how conserved catalytic motifs combine with adaptive structural features in the expanded subtilase family of T. rubrum to regulate activity according to growth stage and substrate availability.