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Identification and functional reconstitution of yeast mitochondrial carrier for S-adenosylmethionine

C M T Marobbio1, G Agrimi, F M Lasorsa

  • 1Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Bari, Italy.

The EMBO Journal
|November 12, 2003
PubMed

Insights

Researchers identified the Saccharomyces cerevisiae mitochondrial carrier protein Sam5p, crucial for S-adenosylmethionine (SAM) transport. This discovery sheds light on essential metabolic pathways and protein functions within yeast mitochondria.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Yeast Genetics

Background:

  • The Saccharomyces cerevisiae genome encodes 35 mitochondrial carrier proteins, with many lacking functional identification.
  • Mitochondrial carrier proteins are vital for transporting metabolites across the inner mitochondrial membrane.

Purpose of the Study:

  • To identify and characterize the mitochondrial carrier protein responsible for S-adenosylmethionine (SAM) transport in yeast.
  • To elucidate the function of Sam5p within the mitochondrial metabolic network.

Main Methods:

  • Gene overexpression in bacteria and protein reconstitution into phospholipid vesicles.
  • Functional characterization using transport assays.
  • Localization studies using Sam5p-GFP fusion protein.
  • Analysis of knockout mutant phenotypes (auxotrophy, petite phenotype).

Main Results:

  • Sam5p was identified as the mitochondrial S-adenosylmethionine (SAM) transporter.
  • Sam5p-GFP fusion protein localized to yeast mitochondria.
  • Cells lacking Sam5p exhibited biotin auxotrophy and a petite phenotype.
  • These phenotypes were rescued by expressing cytosolic SAM synthetase (Sam1p) within mitochondria.

Conclusions:

  • Sam5p is the functional mitochondrial transporter for S-adenosylmethionine (SAM).
  • Mitochondrial SAM transport is essential for biotin biosynthesis and cellular respiration in yeast.
  • This finding provides insights into yeast mitochondrial metabolism and carrier protein function.

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