The Ustilago maydis null mutant strains of the RNA-binding protein UmRrm75 accumulate hydrogen peroxide and melanin.

ABSTRACT: Ustilago maydis is a dimorphic fungus that has emerged as a model organism for the study of fungal phytopathogenicity and RNA biology. In a previous study, we isolated the U. maydis UmRrm75 gene. The deletion of the UmRrm75 gene affected morphogenesis and pathogenicity. UmRrm75 gene encodes a protein containing three RNA recognition motifs. Here we determined that UmRrm75 has chaperone activity in Escherichia coli using the transcription anti-termination assay. Subsequently, we analyzed the growth of ?UmRrm75 mutants at 15?°C and 37?°C, observing that mutant strains had reduced growth in comparison to parental strains. UmRrm75 gene expression was induced under these non-optimal temperatures. ?UmRrm75 mutant colonies displayed a dark-brown color at 28?°C, which was confirmed to be melanin based on spectroscopic analysis and spectrometric data. Furthermore, ?UmRrm75 mutant strains showed the presence of peroxisomes, and increased H₂O₂ levels, even at 28?°C. The ?UmRrm75 mutant strains displayed a higher expression of redox-sensor UmYap1 gene and increased catalase activity than the parental strains. Our data show that deletion of the UmRrm75 gene results in higher levels of H₂O₂, increased melanin content, and abiotic stress sensitivity.

SUBMITTER: Rodriguez-Pina AL 

PROVIDER: S-EPMC6658566 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature