title: Alteration of Wax Ester Content and Composition in Euglena gracilis with Gene Silencing of 3-ketoacyl-CoA Thiolase Isozymes.
abstract: Euglena gracilis produces wax ester under hypoxic and anaerobic culture conditions with a net synthesis of ATP. In wax ester fermentation, fatty acids are synthesized by reversing beta-oxidation in mitochondria. A major species of wax ester produced by E. gracilis is myristyl myristate (14:0-14:0Alc). Because of its shorter carbon chain length with saturated compounds, biodiesel produced from E. gracilis wax ester may have good cold flow properties with high oxidative stability. We reasoned that a slight metabolic modification would enable E. gracilis to produce a biofuel of ideal composition. In order to produce wax ester with shorter acyl chain length, we focused on isozymes of the enzyme 3-ketoacyl-CoA thiolase (KAT), a condensing enzyme of the mitochondrial fatty acid synthesis pathway in E. gracilis. We performed a gene silencing study of KAT isozymes in E. gracilis. Six KAT isozymes were identified in the E. gracilis EST database, and silencing any three of them (EgKAT1-3) altered the wax ester amount and composition. In particular, silencing EgKAT1 induced a significant compositional shift to shorter carbon chain lengths in wax ester. A model fuel mixture inferred from the composition of wax ester in EgKAT1-silenced cells showed a significant decrease in melting point compared to that of the control cells.
authors: Department of Applied Biological Chemistry, Osaka Prefecture University, Osaka, 599-8531, Japan, mami@biochem.osakafu-u.ac.jp.
authors: Masami
authors: M
authors: Nakazawa
authors: Hiroko
authors: H
authors: Andoh
authors: Keiichiro
authors: K
authors: Koyama
authors: Yomi
authors: Y
authors: Watanabe
authors: Takeo
authors: T
authors: Nakai
authors: Mitsuhiro
authors: M
authors: Ueda
authors: Tatsuji
authors: T
authors: Sakamoto
authors: Hiroshi
authors: H
authors: Inui
authors: Yoshihisa
authors: Y
authors: Nakano
authors: Kazutaka
authors: K
authors: Miyatake
mesh_terms: D000102:Acetyl-CoA C-Acyltransferase / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D005056:Euglena gracilis / Q000201:enzymology* / Q000235:genetics; D005285:Fermentation; D020868:Gene Silencing; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009227:Myristic Acids / Q000737:chemistry* / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D044366:Transition Temperature
chemical_list: D007527:Isoenzymes; D009227:Myristic Acids; D015800:Protozoan Proteins; D000102:Acetyl-CoA C-Acyltransferase