Decoding Transcription Regulatory Mechanisms Associated with Coccidioides immitis Phase Transition Using Total RNA

Area of Science:

• Molecular biology
• Mycology
• Infectious diseases

Background:

• Studying emerging infectious diseases is challenging due to pathogen containment requirements.
• Traditional methods for analyzing pathogen gene regulation are often hindered by the need for live samples.
• Valley fever (coccidioidomycosis) is an emerging endemic fungal infection with significant health impacts.

Purpose of the Study:

• To demonstrate the utility of capped small RNA sequencing (csRNA-seq) for studying highly infectious agents.
• To unravel the transcriptional programs and regulatory mechanisms driving the pathogenesis of valley fever.
• To identify key transcription factors involved in the pathogenic growth of Coccidioides immitis.

Main Methods:

• Capped small RNA sequencing (csRNA-seq) was performed on RNA isolated from different stages of Coccidioides immitis.
• Analysis focused on identifying actively initiated transcripts, alternative promoter usage, and cis-regulatory domains.
• The role of WOPR family transcription factors in fungal virulence was investigated.

Main Results:

• csRNA-seq successfully mapped actively initiated transcripts and regulatory elements in Coccidioides immitis.
• Alternative promoter usage and connected cis-regulatory domains critical for pathogenic growth were identified.
• A WOPR homologue (CIMG_02671) was found to be essential for virulence, activating transcription in a motif-dependent manner.

Conclusions:

• csRNA-seq is a powerful and sensitive method for studying gene regulation in highly infectious pathogens under standard laboratory conditions.
• The study provides novel insights into the molecular mechanisms underlying valley fever pathogenesis.
• Identified regulatory factors and transcription factors represent potential targets for therapeutic interventions against coccidioidomycosis.