ORIGINAL PAPER

Current Genetics

, Volume 34, Issue 6, pp 438-448

First online:

YNT20, a bypass suppressor of yme1 yme2, encodes a putative 3′-5′ exonuclease localized in mitochondria of Saccharomyces cerevisiae

  • Theodor HanekampAffiliated withDepartment of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071-3944, USA
  • , P. E. ThorsnessAffiliated withDepartment of Molecular Biology, University of Wyoming, Laramie, WY 82071-3944, USA e-mail: thorsnes@uwyo.edu Tel.:+1-307-766-2038 Fax: +1-307-766-5098

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Abstract

Mutation of YME genes in yeast results in a high rate of mitochondrial DNA escape to the nucleus. The synthetic respiratory growth defect of yme1 yme2 yeast strains is suppressed by recessive mutations in YNT20. Inactivation of YNT20 creates a cold-sensitive respiratory growth defect that is more pronounced in a yme1 background and which is suppressed by yme2. Inactivation of YNT20 causes a qualitative reduction in the rate of mitochondrial DNA escape in yme1, but not yme2, strains, suggesting that YNT20 plays a role in the yme1-mediated mitochondrial DNA escape pathway. YNT20p is a soluble mitochondrial protein that belongs to a subfamily of putative 3′-5′ exonucleases. Furthermore, conserved sequence elements in Yme2p suggest that this protein may also function as an exonuclease.

Key words Mitochondrial DNA escape Mitochondria 3′-5′ exonuclease Yeast