The metabolic basis for the accumulation of acetylated sphingosine bases in the yeast Hansenula ciferri

Yechezkel Barenholz*, Irit Edelman, Shimon Gatt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

1. 1. The contents of free and acetylated sphingosine bases of 25 yeast strains of the genus Hansenula were determined. On the basis of their sphingosine base content, these strains could be divided into three main subgroups: a, low producers which had 2-5 μmoles sphingosine bases per 1 of growth medium; b, intermediate producers (10-40 μmoles per 1) and high producers (120-260 μmoles per 1). 2. 2. All intermediate and high producers belonged to the species Hansenula ciferri. Several strains of this species as well as all species other than H. ciferri were low producers. 3. 3. The intermediate and high producers incorporated radioactivity of 3H or 14C-labelled serine, glucose, palmitate or acetate into sphingosine bases at rates 15-500 × higher than the low producers. 4. 4. There was no correlation between sphingosine base content and the following : Growth rate, DNA content, oxygen uptake, CO2evolution, incorporation of [3H]-leucine and [3H]serine into cell proteins, incorporation of glucose into total fatty acids, as well as levels of palmitic acid thiokinase, glucose-6-phosphatase and glucose-6-phosphate dehydrogenase. 5. 5. An enzyme which acetylates sphingosine bases (sphingosine-acetyl CoA acetyl transferase) was present in the microsomes of the high and intermediate producers but was practically absent from those of the low producers. 6. 6. The results suggest that accumulation of sphingosine bases in the intermediate or high producers is due to increased rates of biosynthesis; the free bases are subsequently acetylated by acetyl-CoA, a reaction catalyzed by the enzyme sphingosine-acetyl-CoA acetyl transferase.

Original languageEnglish
Pages (from-to)458-465
Number of pages8
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume248
Issue number3
DOIs
StatePublished - 14 Dec 1971

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