Isc1 regulates sphingolipid metabolism in yeast mitochondria

Hiroshi Kitagaki, L. Ashley Cowart, Nabil Matmati, Silvia Vaena de Avalos, Sergei A. Novgorodov, Youssef Zeidan, Jacek Bielawski, Lina M. Obeid, Yusuf A. Hannun

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

The Saccharomyces cerevisiae inositol sphingolipid phospholipase C (Isc1p), a homolog of mammalian neutral sphingomyelinases, hydrolyzes complex sphingolipids to produce ceramide in vitro. Epitope-tagged Isc1p associates with the mitochondria in the post-diauxic phase of yeast growth. In this report, the mitochondrial localization of Isc1p and its role in regulating sphingolipid metabolism were investigated. First, endogenous Isc1p activity was enriched in highly purified mitochondria, and western blots using highly purified mitochondrial membrane fractions demonstrated that epitope-tagged Isc1p localized to the outer mitochondrial membrane as an integral membrane protein. Next, LC/MS was employed to determine the sphingolipid composition of highly purified mitochondria which were found to be significantly enriched in α-hydroxylated phytoceramides (21.7 fold) relative to the whole cell. Mitochondria, on the other hand, were significantly depleted in sphingoid bases. Compared to the parental strain, mitochondria from isc1Δ in the post-diauxic phase showed drastic reduction in the levels of α-hydroxylated phytoceramide (93.1% loss compared to WT mitochondria with only 2.58 fold enrichment in mitochondria compared to whole cell). Functionally, isc1Δ showed a higher rate of respiratory-deficient cells after incubation at high temperature and was more sensitive to hydrogen peroxide and ethidium bromide, indicating that isc1Δ exhibits defects related to mitochondrial function. These results suggest that Isc1p generates ceramide in mitochondria, and the generated ceramide contributes to the normal function of mitochondria. This study provides a first insight into the specific composition of ceramides in mitochondria.

Original languageEnglish (US)
Pages (from-to)2849-2861
Number of pages13
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1768
Issue number11
DOIs
StatePublished - Nov 2007
Externally publishedYes

Fingerprint

Sphingolipids
Mitochondria
Metabolism
Yeast
Yeasts
Ceramides
Mitochondrial Membranes
Epitopes
Hydrobromic Acid
Membranes
Sphingomyelin Phosphodiesterase
Ethidium
Type C Phospholipases
Inositol
Respiratory Rate
Chemical analysis
Hydrogen Peroxide
Saccharomyces cerevisiae
Membrane Proteins
Western Blotting

Keywords

  • ISC1
  • Lipidomics
  • Mitochondria
  • Sphingolipid
  • Sphingomyelinase
  • Yeast

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics

Cite this

Kitagaki, H., Cowart, L. A., Matmati, N., Vaena de Avalos, S., Novgorodov, S. A., Zeidan, Y., ... Hannun, Y. A. (2007). Isc1 regulates sphingolipid metabolism in yeast mitochondria. Biochimica et Biophysica Acta - Biomembranes, 1768(11), 2849-2861. https://doi.org/10.1016/j.bbamem.2007.07.019

Isc1 regulates sphingolipid metabolism in yeast mitochondria. / Kitagaki, Hiroshi; Cowart, L. Ashley; Matmati, Nabil; Vaena de Avalos, Silvia; Novgorodov, Sergei A.; Zeidan, Youssef; Bielawski, Jacek; Obeid, Lina M.; Hannun, Yusuf A.

In: Biochimica et Biophysica Acta - Biomembranes, Vol. 1768, No. 11, 11.2007, p. 2849-2861.

Research output: Contribution to journalArticle

Kitagaki, H, Cowart, LA, Matmati, N, Vaena de Avalos, S, Novgorodov, SA, Zeidan, Y, Bielawski, J, Obeid, LM & Hannun, YA 2007, 'Isc1 regulates sphingolipid metabolism in yeast mitochondria', Biochimica et Biophysica Acta - Biomembranes, vol. 1768, no. 11, pp. 2849-2861. https://doi.org/10.1016/j.bbamem.2007.07.019
Kitagaki H, Cowart LA, Matmati N, Vaena de Avalos S, Novgorodov SA, Zeidan Y et al. Isc1 regulates sphingolipid metabolism in yeast mitochondria. Biochimica et Biophysica Acta - Biomembranes. 2007 Nov;1768(11):2849-2861. https://doi.org/10.1016/j.bbamem.2007.07.019
Kitagaki, Hiroshi ; Cowart, L. Ashley ; Matmati, Nabil ; Vaena de Avalos, Silvia ; Novgorodov, Sergei A. ; Zeidan, Youssef ; Bielawski, Jacek ; Obeid, Lina M. ; Hannun, Yusuf A. / Isc1 regulates sphingolipid metabolism in yeast mitochondria. In: Biochimica et Biophysica Acta - Biomembranes. 2007 ; Vol. 1768, No. 11. pp. 2849-2861.
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AU - Zeidan, Youssef

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