Type III polyketide synthases in lichen mycobionts

Area of Science:

• Mycology
• Biochemistry
• Genomics

Background:

• Fungi, including lichen mycobionts, produce diverse secondary metabolites.
• Type I polyketide synthases (PKSs) are currently implicated in lichen compound biosynthesis.
• Type III PKSs are a recently identified class of enzymes in fungi.

Purpose of the Study:

• To investigate the presence and phylogenetic relationships of type III PKS genes in lichen mycobionts.
• To determine if type III PKS genes are ubiquitous across fungal lineages.

Main Methods:

• Utilized CODEHOP strategy with degenerate PCR primers to identify type III CHS-like genes.
• Screened available fungal genomes for type III PKS genes.
• Performed phylogenetic analysis of aligned type III PKS sequences.

Main Results:

• Identified type III-like genes in diverse, unrelated lichen mycobionts.
• Found type III PKS genes in lichen mycobionts are closely related to those in non-lichenized fungi.
• Established that type III PKS genes are not closely related to bacterial or plant homologs.

Conclusions:

• Type III PKS genes are ubiquitous in fungi, including lichen-forming fungi.
• The presence of type III PKS genes in diverse lichens suggests an ancient evolutionary origin.
• The specific functions of type III PKSs in lichen biology require further investigation.