Theses and Dissertations


Adef Othan

Issuing Body

Mississippi State University


Gordon, Donna M.

Committee Member

Kavazis, Andreas N.

Committee Member

Stewart, James A., Jr.

Date of Degree


Original embargo terms

MSU Only Indefinitely

Document Type

Graduate Thesis - Campus Access Only


Biological Sciences

Degree Name

Master of Science


College of Arts and Sciences


Department of Biological Sciences


The rhomboid protease, Pcp1p, localizes to the mitochondrial inner membrane in Saccharomyces cerevisiae. The 346 amino acid protein contains an N-terminal mitochondria targeting signal followed by 6 transmembrane helices. Pcp1p substrates include, Ccp1p and Mgm1p; both soluble intermembrane space proteins after Pcp1p cleavage. Haploid pcp1 mutants grow slow, lose mitochondrial DNA, and have abnormal mitochondrial morphology; phenotypes similar to mgm1 mutants. Processing of Mgm1p depends on Pcp1p activity, matrix ATP levels, and a functional Tim23-Pam complex. This suggests a potential link between Pcp1p and the Tim23 complex. To test this hypothesis, epitope tagged versions of Pcp1p, Tim23p, Tim21p, and Pam18p were generated for use in immunoprecipitation and sucrose gradient ultracentrifugation experiments. The data suggest that Pcp1p exists in a higher order protein complex that may contain multiple Pcp1p subunits and components of the Tim23 translocon. The importance of this interaction in the processing of precursor proteins remains to be determined.