Knockout of fatty acid desaturase genes in Pichia pastoris GS115 and its effect on the fatty acid biosynthesis and physiological consequences.
Unsaturated fatty acids (UFAs), including oleic acid (OA, C18:1n-9), linoleic acid (LA, C18:2n-6) and α-linolenic acid (ALA, C18:3n-3), are major components of membrane lipids in Pichia pastoris GS115. In order to clarify the biosynthesis pathway of UFAs on the molecular level and investigate their possible roles in growth and development of this strain, we here report modified strains with disrupted desaturase gene by homologous recombination. Gas chromatography analysis of fatty acid composition in the corresponding mutants confirmed that ∆(12)-desaturase encoded by Fad12 was responsible for the formation of LA, and ALA was synthesized by ∆(15)-desaturase encoded by Fad15. Simultaneous deletion of Fad9A and Fad9B was lethal and supplementation of OA could restore growth, indicating that possibly both Fad9A and Fad9B encoded ∆(9)-desaturase that converted SA into OA. Phenotypic analysis demonstrated that wild type and Fad15 mutant grew at almost the same rate, Fad12 mutant grew much slower than these two strains. Moreover, OA was positively correlated to cold tolerance and ethanol tolerance of GS115, whereas LA and ALA did not affect cold tolerance and ethanol tolerance of it. In addition, we showed that tolerance of GS115 to high concentration of methanol was independent of these three UFAs.
Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, Nankai University, Tianjin, People's Republic of China.
Ai-Qun
AQ
Yu
Jian-Chun
JC
Zhu
Biao
B
Zhang
Lai-Jun
LJ
Xing
Ming-Chun
MC
Li
D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis / Q000096:biosynthesis*; D010843:Pichia / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D013312:Stress, Physiological / Q000235:genetics
D005227:Fatty Acids; D044943:Fatty Acid Desaturases