A nuclear-encoded intein in the fungal pathogen Cryptococcus neoformans

Area of Science:

• Molecular Biology
• Mycology
• Genetics

Background:

• Cryptococcus neoformans is a significant human fungal pathogen, particularly affecting immunocompromised individuals like AIDS patients.
• Inteins are protein splicing elements found within genes, capable of post-translational removal and ligation of flanking protein sequences.
• The PRP8 gene encodes a crucial component of the spliceosome, essential for mRNA processing in eukaryotes.

Purpose of the Study:

• To identify and characterize novel intein-like sequences in eukaryotic genomes.
• To investigate the presence and nature of protein splicing elements in the fungal pathogen Cryptococcus neoformans.
• To explore the potential of identified inteins as therapeutic targets for cryptococcal infections.

Main Methods:

• Comparative sequence analysis of the PRP8 gene in Cryptococcus neoformans against homologous genes from other organisms.
• Bioinformatic identification of intein-like sequences and their domains.
• Analysis of the intein's location and relationship to known inteins in other yeast species.

Main Results:

• An intein-like sequence, designated Cne PRP8 intein, was identified within the PRP8 gene of Cryptococcus neoformans.
• This intein is an in-frame insertion relative to PRP8 genes of other species and shares similarities with known yeast inteins.
• The Cne PRP8 intein lacks a recognizable internal endonuclease domain, distinguishing it from some other inteins.
• This represents only the second intein discovered in a eukaryote nuclear genome, with previously identified ones found in VMA gene homologues.

Conclusions:

• The Cne PRP8 intein is a novel protein splicing element found in the genome of a major fungal pathogen.
• Its presence in the conserved PRP8 gene suggests a potential role in essential cellular processes.
• The Cne PRP8 intein presents a promising new avenue for developing targeted therapies against cryptococcal infections.