The mitochondrial genome of Candida albicans

Author

James Andrew Shaw

Date of Award

5-1989

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Microbiology

Major Professor

W. Stuart Riggsby

Committee Members

David A. Brian, Frank W. Larimer, Jeffery M. Becker

Abstract

Candida albicans is an opportunistic, pathogenic fungus which is primarily the cause of topical infections of the mucousal surfaces of the mouth and vagina. As an opportunistic pathogen it can also present serious problems for the immunocompromised patient. As part of the routine characterization of this medically important organism and because of the availability of direct methods to locate mitochondrial genes this project was undertaken to study the structure and function of its mitochondrial genome.

The six EcoRI fragments of the 40Kb circular mitochondrial (mt) DNA were cloned into the EcoRI site of pBR322. A detailed restriction map was prepared for 11 restriction endonucleases. Probes specific for the eight ubiquitous mitochondrial genes (large and small ribosomal RNA's [rRNA], cytochrome oxidase subunits I, II, and III, ATPase subunits 6 and 9, and cytochrome b) were derived from a special class of petite mutants of Saccharomyces cerevisiae. These probes were used in Southern blot experiments to detect those mitochondrial restriction fragments having sequence homology with the S. cerevisiae gene probes. Expression of the mitochondrial genes was demonstrated by standard Northern blot experiments.

Detailed restriction mapping of the mtDNA of Candida aibicans confirms the existence of a large inverted duplication. As is the case with some other mt and chloroplast DMAs, the non-duplicated regions of the molecule occur in two orientations with respect to each other, indicating that internal recombination occurs. Like other mtONA's, the C. albicans mtDNA contains a single Sa/l restriction site, located near one end of the large rRNA gene. In contrast to other cases however, the inverted duplication does not appear to contain any sequences coding for rRNA.

The eight ubiquitous mitochondrial structural genes mentioned previously have been located on the mtDNA of Candida albicans. The relative order of these genes reveals yet another unique arrangement for fungal mitochondrial genomes. The gene order in C. albicans is most similar to that of Saccharomyces exiguus. All eight genes are expressed and produce transcripts of sizes comparable to the homologous transcripts in other fungi. The genes encoding cytochrome oxidase subunit I, cytochrome b and cytochrome oxidase subunit II appear to have introns.

Recommended Citation

Shaw, James Andrew, "The mitochondrial genome of Candida albicans. " PhD diss., University of Tennessee, 1989.
https://trace.tennessee.edu/utk_graddiss/11762