The DNA binding parvulin Par17 is targeted to the mitochondrial matrix by a recently evolved prepeptide uniquely present in Hominidae.
BACKGROUND
The parvulin-type peptidyl prolyl cis/trans isomerase Par14 is highly conserved in all metazoans. The recently identified parvulin Par17 contains an additional N-terminal domain whose occurrence and function was the focus of the present study.


RESULTS
Based on the observation that the human genome encodes Par17, but bovine and rodent genomes do not, Par17 exon sequences from 10 different primate species were cloned and sequenced. Par17 is encoded in the genomes of Hominidae species including humans, but is absent from other mammalian species. In contrast to Par14, endogenous Par17 was found in mitochondrial and membrane fractions of human cell lysates. Fluorescence of EGFP fusions of Par17, but not Par14, co-localized with mitochondrial staining. Par14 and Par17 associated with isolated human, rat and yeast mitochondria at low salt concentrations, but only the Par17 mitochondrial association was resistant to higher salt concentrations. Par17 was imported into mitochondria in a time and membrane potential-dependent manner, where it reached the mitochondrial matrix. Moreover, Par17 was shown to bind to double-stranded DNA under physiological salt conditions.


CONCLUSIONS
Taken together, the DNA binding parvulin Par17 is targeted to the mitochondrial matrix by the most recently evolved mitochondrial prepeptide known to date, thus adding a novel protein constituent to the mitochondrial proteome of Hominidae.
Kessler
Daniel
D
Department of Structural and Medicinal Biochemistry, Center for Medical Biotechnology - ZMB, University of Duisburg-Essen, 45117 Essen, Germany. daniel.kessler@uni-due.de
Papatheodorou
Panagiotis
P
Stratmann
Tina
T
Dian
Elke Andrea
EA
Hartmann-Fatu
Cristina
C
Rassow
Joachim
J
Bayer
Peter
P
Mueller
Jonathan Wolf
JW
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002458:Cell Fractionation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D006367:HeLa Cells; D015186:Hominidae / Q000235:genetics*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000235:genetics* / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D021381:Protein Transport; D016415:Sequence Alignment
D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; C000606846:PIN1 protein, human; C000606848:PIN4 protein, human; D019696:Peptidylprolyl Isomerase