Squalene is a naturally occurring triterpene with wide industrial applications. Due to limited natural resources, production of this valuable lipid in yeast is of high commercial relevance. Typically low levels of squalene in yeast can be significantly increased by specific cultivation conditions or genetic modifications. Under normal conditions, excess squalene is stored in lipid droplets (LD), while in a Saccharomyces cerevisiae mutant unable to form LD it is distributed to cellular membranes. We present here the evidence that squalene accumulation in this LD-less mutant treated with squalene monooxygenase inhibitor terbinafine induces growth defects and loss of viability. We show that plasma membrane malfunction is involved in squalene toxicity. We have found that subinhibitory concentrations of terbinafine increased the sensitivity of LD-less mutant to several membrane-active substances. Furthermore, squalene accumulation in terbinafine-treated LD-less cells disturbed the maintenance of membrane potential and increased plasma membrane permeability to rhodamine 6G. LD-less cells treated with terbinafine showed also high sensitivity to osmotic stress. To confirm the causal relationship between squalene accumulation, loss of viability and impaired plasma membrane functions we treated LD-less cells simultaneously with terbinafine and squalene synthase inhibitor zaragozic acid. Reduction of squalene levels by zaragozic acid improved cell growth and viability and decreased plasma membrane permeability to rhodamine 6G in terbinafine-treated LD-less cells. Our results support the hypothesis that plasma membrane malfunction is involved in the mechanisms of squalene lipotoxicity in yeast cells with defective lipid storage.
Squalene is a natural triterpenoid present virtually in all taxonomic groups. Its use for improving human health is rooted in ancient human history as several Pacific nations consumed the oil from livers of deep-sea sharks with high squalene content to improve their health and extend the life. In addition to the use as nutritional supplement, this molecule finds today many applications in pharmacology and cosmetics, or as a valuable industrial lubricant. Broad application potential of squalene is related to its physico-chemical characteristics, antioxidant activity and to its ability to interact with cell membranes. The industrial use of squalene is limited by short natural resources. Even today squalene is acquired mainly from shark liver oil; however, this source is no more tenable from the environmental viewpoint. Plant sources (e.g. olives, amaranth seeds) and particularly microbial production are thus gaining importance as promising alternatives for extended industrial use of squalene.
- MeSH
- biotechnologie MeSH
- skvalen * farmakologie chemická syntéza chemie terapeutické užití MeSH
- Publikační typ
- práce podpořená grantem MeSH
The role of archaeal membrane and its lipid constituents was investigated in bioenergetic functions of Methanothermobacter thermautotrophicus. The effects were determined of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, pravastatin, on lipid composition, and its impact on some bioenergetic functions of treated cells. Pravastatin remarkably inhibited the growth of M. thermautotrophicus. On membrane level, pravastatin treatment modulated the composition of the mixture of squalene and hydrosqualene derivatives as well as the activities of ATPase, A1Ao-ATP synthase and Na+/H+ antiporter. SDS-PAGE of chloroform-methanol extracts of membranes from control and pravastatin-treated cells revealed changes in the amount of AtpK proteolipids, which suggests that pravastatin modifies cell-membrane composition, hereby modulating the properties of some membrane-bound enzymes participating in energy transformation in methanoarchaea.
- MeSH
- buněčná membrána chemie metabolismus účinky léků MeSH
- elektroforéza v polyakrylamidovém gelu MeSH
- energetický metabolismus účinky léků MeSH
- financování organizované MeSH
- membránové lipidy analýza MeSH
- Methanobacteriaceae MeSH
- Na(+)-H(+) antiport metabolismus MeSH
- pravastatin farmakologie MeSH
- protonové ATPasy metabolismus MeSH
- skvalen analýza MeSH
- statiny farmakologie MeSH
