Crz1p Regulates pH Homeostasis in Candida glabrata by Altering Membrane Lipid Composition

Yan, Dongni; Lin, Xiaobao; Qi, Yanli; Liu, Hui; Chen, Xiulai; Li, Liming; Chen, Jian

doi:10.1128/aem.02186-16

Cited by 33 publications

(34 citation statements)

References 55 publications

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“…Alteration of membrane composition serves as an adaptive response to variations in pH (33). Our genome-wide analyses confirmed the critical role played by the composition and structure of the membrane lipid and its physiological function in acid tolerance (46)(47)(48).…”

Section: Discussionsupporting

confidence: 52%

“…A set of genes involved in fatty acid biosynthesis, elongation, unsaturation, and metabolism were downregulated. Many of these genes were reported to be involved in the length and number of double bonds in fatty acids and in the response to various forms of stress (33,34), which may influence the species of phospholipid produced (35). Meanwhile, key genes involved in phospholipid and sphingolipid metabolism were also downregulated, thus contributing to a decreased phospholipid and sphingolipid biosynthesis in the med15BΔ strain.…”

Section: Discussionmentioning

confidence: 95%

“…Changes in the lipid composition of the med15BΔ strain might affect the activity of membrane proteins, which are essential for barrier function (50,51). The transcription factor Crz1 was shown to function in low-pH tolerance in C. glabrata (33). In this study, we explored the role of C. glabrata Mediator subunit Med15B in providing tolerance to low-pH conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Freeze-dried samples were obtained as described above, and 50 mg dried cells was used for saponification. The saponified samples were resuspended in hexane for total sterol extraction as described previously (33). Samples of total sterol were analyzed by gas chromatography-mass spectrometry (GC-MS) (Waters, Santa Clara, MA) with a fused-silica capillary column (30 m by 0.25 mm by 0.25 m DB-5MS stationary-phase column; J&W Scientific, Folsom, CA, USA) (56).…”

Section: Med15b Regulates C Glabrata Acid Tolerance Applied and Envimentioning

confidence: 99%

“…Samples were disrupted with an MP FastPrep-homogenizer, and the membrane fractions were isolated from the cell-free supernatant by centrifugation as described previously (60). Membrane H ϩ -ATPase (H ϩ -ATPase) activity was determined according to the amount of inorganic phosphate (P i ) released from ATP in the reaction mixture as described previously (33). A 5-g membrane fraction was incubated in 120 l assay mixture A (5 mM ATP, 10 mM MgSO 4 , 50 mM KCl, 50 mM MES, 50 mM KNO 3 , 50 mM NaN 3 , 0.2 mM ammonium molybdate [pH 6.0]), where MES is 2-(N-morpholino)ethanesulfonic acid, at 30°C for 30 min.…”

Section: Targetmentioning

confidence: 99%

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Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition

Liu

et al. 2017

Appl Environ Microbiol

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Candida glabrata is a promising producer of organic acids. To elucidate the physiological function of the Mediator tail subunit Med15B in the response to low-pH stress, we constructed a deletion strain, C. glabrata med15BΔ, and an overexpression strain, C. glabrata HTUΔ/CgMED15B. Deletion of MED15B caused biomass production, glucose consumption rate, and cell viability to decrease by 28.3%, 31.7%, and 26.5%, respectively, compared with those of the parent (HTUΔ) strain at pH 2.0. Expression of lipid metabolism-related genes was significantly downregulated in the med15BΔ strain, whereas key genes of ergosterol biosynthesis showed abnormal upregulation. This caused the proportion of C 18:1 fatty acids, the ratio of unsaturated to saturated fatty acids (UFA/SFA), and the total phospholipid content to decrease by 11.6%, 27.4%, and 37.6%, respectively. Cells failed to synthesize fecosterol and ergosterol, leading to the accumulation and a 60.3-fold increase in the concentration of zymosterol. Additionally, cells showed reductions of 69.2%, 11.6%, and 21.8% in membrane integrity, fluidity, and H ϩ -ATPase activity, respectively. In contrast, overexpression of Med15B increased the C 18:1 levels, total phospholipids, ergosterol content, and UFA/SFA by 18.6%, 143.5%, 94.5%, and 18.7%, respectively. Membrane integrity, fluidity, and H ϩ -ATPase activity also increased by 30.2%, 6.9%, and 51.8%, respectively. Furthermore, in the absence of pH buffering, dry weight of cells and pyruvate concentrations were 29.3% and 61.2% higher, respectively, than those of the parent strain. These results indicated that in C. glabrata, Med15B regulates tolerance toward low pH via transcriptional regulation of acid stress response genes and alteration in lipid composition. IMPORTANCE This study explored the role of the Mediator tail subunit Med15B in the metabolism of Candida glabrata under acidic conditions. Overexpression of MED15B enhanced yeast tolerance to low pH and improved biomass production, cell viability, and pyruvate yield. Membrane lipid composition data indicated that Med15B might play a critical role in membrane integrity, fluidity, and H ϩ -ATPase activity homeostasis at low pH. Thus, controlling membrane composition may serve to increase C. glabrata productivity at low pH.KEYWORDS Candida glabrata, Mediator subunit Med15B, low-pH stress, transcriptomics, membrane lipid T he Mediator coactivator complex is required for transcription initiation in eukaryotes (1, 2). It is recruited by transcription activators and conveys regulatory information from gene-specific regulators to promoters (3, 4). Mediator can influence almost all stages of transcription and coordinated processes such as chromatin remodeling, transcription elongation, and posttranslational modifications (5, 6). Mediator is a multisubunit assembly comprising four modules: head, middle, tail, and cyclin-dependent kinase 8 (CDK8) (7). The head and middle modules are highly

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Section: Discussionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Med15b Regulates C Glabrata Acid Tolerance Applied and Envimentioning

confidence: 99%

Section: Targetmentioning

confidence: 99%

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Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition

Liu

et al. 2017

Appl Environ Microbiol

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Engineering of membrane phospholipid component enhances salt stress tolerance in Saccharomyces cerevisiae

Yin

Zhu

Luo

et al. 2020

Biotech & Bioengineering

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To increase the growth of industrial strains under environmental stress, the Saccharomyces cerevisiae BY4741 salt-tolerant strain Y00 that tolerates 1.2 M NaCl was cultured through nitroguanidine mutagenesis. The metabolomics and transcription data of Y00 were compared with those of the wild-type strain BY4741. The comparison identified two genes related to salt stress tolerance, cds1 and cho1. Modular assembly of cds1 and cho1 redistributed the membrane phospholipid component and decreased the ratio of anionic-to-zwitterionic phospholipid in strain Y03 that showed the highest salt tolerance. Therefore, significantly increased membrane potential and membrane integrity helped strain Y03 to resist salt stress (1.2 M NaCl). This study provides an effective membrane engineering strategy to enhance salt stress tolerance.

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Dynamic regulation of membrane integrity to enhance l‐malate stress tolerance in Candida glabrata

Liang

Zhou

et al. 2021

Biotech & Bioengineering

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Microbial cell factories provide a sustainable and economical way to produce chemicals from renewable feedstocks. However, the accumulation of targeted chemicals can reduce the robustness of the industrial strains and affect the production performance. Here, the physiological functions of Mediator tail subunit CgMed16 at L-malate stress were investigated. Deletion of CgMed16 decreased the survival, biomass, and half-maximal inhibitory concentration (IC 50 ) by 40.4%, 34.0%, and 30.6%, respectively, at 25 g/L L-malate stress. Transcriptome analysis showed that this growth defect was attributable to changes in the expression of genes involved in lipid metabolism. In addition, tolerance transcription factors CgUSV1 and CgYAP3 were found to interact with CgMed16 to regulate sterol biosynthesis and glycerophospholipid metabolism, respectively, ultimately endowing strains with excellent membrane integrity to resist L-malate stress. Furthermore, a dynamic tolerance system (DTS) was constructed based on CgUSV1, CgYAP3, and an L-malate-driven promoter P cgr-10 to improve the robustness and productive capacity of Candida glabrata. As a result, the biomass, survival, and membrane integrity of C. glabrata 012 (with DTS) increased by 22.6%, 31.3%, and 53.8%, respectively, compared with those of strain 011 (without DTS). Therefore, at shake-flask scale, strain 012 accumulated 35.5 g/L L-malate, and the titer and productivity of L-malate increased by 32.5% and 32.1%, respectively, compared with those of strain 011. This study provides a novel strategy for the rational design and construction of DTS for dynamically enhancing the robustness of industrial strains.

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Crz1p Regulates pH Homeostasis in Candida glabrata by Altering Membrane Lipid Composition

Cited by 33 publications

References 55 publications

Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition

Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition

Engineering of membrane phospholipid component enhances salt stress tolerance in Saccharomyces cerevisiae

Dynamic regulation of membrane integrity to enhance l‐malate stress tolerance in Candida glabrata

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