The telomerase reverse transcriptase subunit from the dimorphic fungus Ustilago maydis.

Area of Science:

• Mycology
• Molecular Biology
• Genetics

Background:

• Telomerase, an enzyme maintaining telomere length, is vital for cellular lifespan.
• The reverse transcriptase subunit (TERT) is a key component of telomerase.
• Ustilago maydis serves as a model organism for studying fungal genetics and biology.

Purpose of the Study:

• To investigate the function of the telomerase reverse transcriptase subunit (Trt1) in the dimorphic fungus Ustilago maydis.
• To characterize the effects of trt1 disruption on fungal growth, survival, and reproduction.
• To explore telomere maintenance mechanisms and potential alternative survival strategies in Ustilago maydis.

Main Methods:

• Gene disruption of the trt1 gene in Ustilago maydis.
• Phenotypic analysis of trt1 mutants, including growth rate, replicative potential, and survival assays.
• Telomerase activity assays in wild-type and mutant strains.
• Complementation of the mutant strain with a plasmid expressing Trt1.
• In planta crosses and terminal restriction fragment analysis.

Main Results:

• Disruption of trt1 resulted in senescence-like phenotypes, including delayed growth, reduced replicative potential, and decreased survival.
• Telomerase activity was absent in trt1 disruption mutants but present in wild-type strains.
• Complementation with Trt1 restored growth proficiency and replicative potential in the mutant.
• Trt1 was essential for teliospore formation in homozygous diploids and telomerase showed haploinsufficiency in heterozygous diploids.
• Terminal restriction fragment analysis suggested the presence of alternative survival mechanisms.

Conclusions:

• The reverse transcriptase subunit of telomerase (Trt1) is essential for the viability and reproductive fitness of Ustilago maydis.
• Telomerase plays a critical role in telomere maintenance and overall cellular health in this fungus.
• Ustilago maydis may possess alternative mechanisms for telomere maintenance or cellular survival, similar to those observed in other yeast species.