Stable association of 70-kDa heat shock protein induces latent multisite specificity of a unisite-specific endonuclease in yeast mitochondria

J Biol Chem. 1999 Sep 3;274(36):25682-90. doi: 10.1074/jbc.274.36.25682.

Abstract

The multisite-specific endonuclease Endo.SceI of yeast mitochondria is unique among endonucleases because its 50-kDa subunit forms a stable dimer with the mitochondrial 70-kDa heat shock protein (mtHSP70), which otherwise fulfills a chaperone function by binding transiently to unfolded proteins. Here we show that the mtHSP70 subunit confers broader sequence specificity, greater stability, and higher activity on the 50-kDa subunit. The 50-kDa subunit alone displayed weaker activity and highly sequence-specific endonuclease activity. The 50-kDa protein exists as a heterodimer with mtHSP70 in vivo, allowing Endo.SceI to cleave specifically at multiple sites on mitochondrial DNA. Endo.SceI may have evolved from a highly specific endonuclease that gained broader sequence specificity after becoming a stable partner of mtHSP70.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Deoxyribonucleases, Type II Site-Specific / chemistry
  • Deoxyribonucleases, Type II Site-Specific / genetics
  • Deoxyribonucleases, Type II Site-Specific / metabolism*
  • Dimerization
  • Enzyme Induction
  • HSP70 Heat-Shock Proteins / metabolism*
  • Mitochondria / metabolism*
  • Molecular Chaperones / metabolism
  • Molecular Sequence Data
  • Protein Binding
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins
  • Substrate Specificity

Substances

  • HSP70 Heat-Shock Proteins
  • Molecular Chaperones
  • Saccharomyces cerevisiae Proteins
  • SCEI protein, S cerevisiae
  • Deoxyribonucleases, Type II Site-Specific

Associated data

  • GENBANK/AF159242