Up-regulated expression of desaturase genes of Mucor rouxii in response to low temperature associates with pre-existing cellular fatty acid constituents

Abstract

Transcriptional response of desaturase genes to low temperature was investigated in the dimorphic fungus Mucor rouxii. The two morphological forms of M. rouxii, yeast-like and mycelial cells containing different fatty acid profiles were shifted from 30 to 10°C. Both cultures exhibited significantly altered fatty acid composition, whose content in polyunsaturated fatty acids increased as consequence of the temperature shift and was accompanied by a reduction of C18:1Δ(9) about 2 h after the temperature shift. These changes were particularly significant in phosphatidylcholine and phosphatidylethanolamine fractions. Moreover, the fatty acid profiles of monoacylglycerol and diacylglycerol were also modulated in response to the lower temperature of incubation. The changes of membrane lipids of M. rouxii were due to the cold-induced expression of Δ(9)-, Δ(12)- and Δ(6)-desaturase genes. Although the mRNA levels of the three desaturases were transiently induced by lowering the temperature, the pre-existing composition of fatty acid profiles of mycelial and yeast-like forms of M. rouxii may have lead to different expression profiles of desaturase genes that modified their membrane physical state under cold shock. While expression of Δ(12)-desaturase gene contributed mainly to cold acclimation of mycelia, Δ(9)-desaturase expression was the main transcript identified in the yeast-like culture after temperature shift.

Differential expression of desaturase genes and changes in fatty acid composition ofMortierellasp. AGED in response to environmental factors

“…AGED was basically consistent with the transcript levels of Δ9‐, Δ12‐ and Δ6‐desaturase genes in response to temperature. Desaturase gene expression was related to temperature shift, and the Δ9‐desaturase gene was more sensitive to temperature shift, which was consistent with other reports . The Δ9‐desaturase gene, which catalyzes the first step of PUFA synthesis by converting stearic acid (STA, C18:0) to oleic acid (OLA, C18:1), was more strongly regulated than other desaturase genes .…”

“…The Δ9‐desaturase gene, which catalyzes the first step of PUFA synthesis by converting stearic acid (STA, C18:0) to oleic acid (OLA, C18:1), was more strongly regulated than other desaturase genes . In M. rouxii , the transcript levels of Δ9‐desaturase increased to a greater extent than those of Δ12‐ and Δ6‐desaturases at low temperature . In cyanobacteria, there was no significant difference in the expression of Δ9‐desaturase gene desC at 22 and 38 °C, while that of Δ12‐desaturase gene desA was 3‐fold higher at 22 °C than at 38 °C.…”

“…Further study is needed to elucidate their response mechanism. Mucor rouxii exhibited significant changes in fatty acid composition when shifted from 30 to 10 °C . In P. pastoris GS115, the transcript levels of desaturase genes were also up‐regulated rapidly after the temperature shift‐down …”

Physiological Traits of Dihomo-γ-Linolenic Acid Production of the Engineered Aspergillus oryzae by Comparing Mathematical Models

“…Low DGLA proportions have also been reported for the recombinant strains of Mucor circinelloides (5.7% DGLA in TFA) and Saccharomyces cerevisiae (3.5% DGLA in TFA) even though they were challenged by cultivating at low temperatures (Yazawa et al, 2007;Khan et al, 2019). Actually, low-temperature stress has been used for enhancing the PUFA proportion, which has been thought to be involved in adaptation mechanism of the microbial cells for increasing membrane fluidity (Vigh et al, 2005;Cheawchanlertfa et al, 2011). The high DGLA proportion found in the CSH/ML culture grown at normal temperature can be possibly explained by the effect of predominant amino acids (glutamic acid and aspartic acid) in ML.…”

Genome-wide identification of the fatty acid desaturases gene family in four Aspergillus species and their expression profile in Aspergillus oryzae

“…On the other hand, researches related to the function of fatty acid desaturases from fungus on stress response are also a hotspot. Cheawchanlertfa et al revealed that the up-regulated expression of desaturase genes from Mucor rouxii was responded to low temperature (Cheawchanlertfa et al 2011 ). The fatty acid desaturases genes in A. oryzae were up-regulated in response to salinity stress (He et al 2017a ).…”