Reanalysis of the mitochondrial genome of the pneumocandin- producing fungus Glarea lozoyensis

Abstract:

[Objective] Glarea lozoyensis is a filamentous fungus used for industrial production of the antifungal drug caspofungin. Previously, the mitochondrial genome (mitogenome) of a mutant strain ATCC 74030 was reported. The purpose of the current study is to test if mutagen treatments have caused changes on the mitogenome of the fungus. [Methods] The mitogenome of the wild strain ATCC 20868 was assembled and compared with the published mitogenome of ATCC 74030. PCR assays were done for both strains. Additional analyses were done using correct mitogenome sequences. [Results] We successfully assembled the mitogenome of the wild strain ATCC 20868. Initial comparison of the mitogenomes of the wild and mutant strains indicated six variable nucleotide sites and two regions with length variations. PCR assays and subsequent sequencing, however, showed no difference between the two strains. The differences observed from initial comparison were due to sequence errors present in the published mitogenome of ATCC 74030. Interestingly, three intron-containing tRNAs and a rnpB gene were detected in the mitogenome of the fungus. Obvious repetitive elements were identified within the G. lozoyensis mitogenome, and duplication events were identified between its mitochondrial and nuclear genomes. [Conclusion] We verified that there existed erroneous sequences in the published mitogenome of ATCC 74030; mutagens did not cause variations on the mitogenome of G. lozoyensis. We reported the authentic mitogenome sequence of G. lozoyensis and found frequent gene transfer between mitochondrial and nuclear genomes in the fungus.