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Open Access Research article

The DNA binding parvulin Par17 is targeted to the mitochondrial matrix by a recently evolved prepeptide uniquely present in Hominidae

Daniel Kessler1, Panagiotis Papatheodorou2, Tina Stratmann1, Elke Andrea Dian2, Cristina Hartmann-Fatu1, Joachim Rassow2, Peter Bayer1* and Jonathan Wolf Mueller1*

Author Affiliations

1 Department of Structural and Medicinal Biochemistry, Center for Medical Biotechnology – ZMB, University of Duisburg-Essen, 45117 Essen, Germany

2 Institut für Physiologische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany

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BMC Biology 2007, 5:37  doi:10.1186/1741-7007-5-37

Published: 17 September 2007

Abstract

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.

Conclusion

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.