Enhancement of Sphingolipid Synthesis Improves Osmotic Tolerance of Saccharomyces cerevisiae

Abstract

To enhance the growth performance of Saccharomyces cerevisiae under osmotic stress, mutant XCG001, which tolerates up to 1.5 M NaCl, was isolated through adaptive laboratory evolution (ALE). Comparisons of the transcriptome data of mutant XCG001 and the wild-type strain identified ELO2 as being associated with osmotic tolerance. In the ELO2 overexpression strain (XCG010), the contents of inositol phosphorylceramide (IPC; t18:0/26:0), mannosylinositol phosphorylceramide [MIPC; t18:0/22:0(2OH)], MIPC (d18:0/22:0), MIPC (d20:0/24:0), mannosyldiinositol phosphorylceramide [M(IP)2C; d20:0/26:0], M(IP)2C [t18:0/26:0(2OH)], and M(IP)2C [d20:0/26:0(2OH)] increased by 88.3 times, 167 times, 63.3 times, 23.9 times, 27.9 times, 114 times, and 208 times at 1.0 M NaCl, respectively, compared with the corresponding values of the control strain XCG002. As a result, the membrane integrity, cell growth, and cell survival rate of strain XCG010 increased by 24.4% ± 1.0%, 21.9% ± 1.5%, and 22.1% ± 1.1% at 1.0 M NaCl, respectively, compared with the corresponding values of the control strain XCG002 (wild-type strain with a control plasmid). These findings provided a novel strategy for engineering complex sphingolipids to enhance osmotic tolerance. IMPORTANCE This study demonstrated a novel strategy for the manipulation of membrane complex sphingolipids to enhance S. cerevisiae tolerance to osmotic stress. Elo2, a sphingolipid acyl chain elongase, was related to osmotic tolerance through transcriptome analysis of the wild-type strain and an osmosis-tolerant strain generated from ALE. Overexpression of ELO2 increased the content of complex sphingolipid with longer acyl chain; thus, membrane integrity and osmotic tolerance improved.

The Plasma Membrane at the Cornerstone Between Flexibility and Adaptability: Implications for Saccharomyces cerevisiae as a Cell Factory

“…These works highlight that different membrane compositions can be advantageous toward the same stress agent. In both works, Yin et al (2020) and Zhu et al (2020) , the levels of PS and PE were increased, 35.5% and 15, 25.2, and 18.9%, respectively. However, when ELO2 was overexpressed the levels of PC, PA, and PI did not change.…”

“…Through an adaptive laboratory evolution experiment, Zhu et al (2020) were able to isolate a strain with improved tolerance to osmotic stress. Transcriptome sequencing (RNA-seq) suggested that mRNA levels of ELO2 were differentially upregulated in the isolated strain.…”

Sphingolipid metabolism, transport, and functions in plants: Recent progress and future perspectives

“…Plants also contain traces of another four C18 LCBs (d18:2(4E,8E), d18:2 (4E,8Z), t18:2 [with unknown structure], and a unique d18:1 [with a C10=C11 double bond]), one C20 LCB t20:0, and special d21:1 or d22:1 LCBs (the last two LCBs contain a C7=C8 double bond), which have been validated by either mass spectrometry (MS) or nuclear magnetic resonance (NMR) ( Kimberlin et al., 2013 ; Ngo et al., 2020 ; Panzenboeck et al., 2020 ; Wang et al., 2020a ). However, the two common LCBs d20:0 and d20:1, which are detected in animals and Saccharomyces cerevisiae , are rarely reported in plant samples ( De Castro Levatti et al., 2017 ; Zhu et al., 2020 ).…”

Engineering membrane asymmetry to increase medium‐chain fatty acid tolerance in Saccharomyces cerevisiae

“…Moreover, an engineered yeast strain showed a 14.2% increase in the final biomass compared with that of the control (Yin et al, 2020). (3) The membrane functions, including membrane integrity, membrane fluidity, and membrane permeability, can be regulated by engineering the membrane lipid profile (Z. Tan et al, 2017; G. Zhu et al, 2020) and transcriptional factors (Ling et al, 2015). As an example, to increase the stress tolerance caused by octanoic acid, Z. Tan et al (2017) successfully increased octanoic acid stress tolerance in E. coli via the combinatorial deletion of ompF and increased expression of fadL .…”