Molecular characterization of a bifunctional glyoxylate cycle enzyme, malate synthase/isocitrate lyase, in Euglena gracilis.
Euglena gracilis induced glyoxylate cycle enzymes when ethanol was fed as a sole carbon source. We purified, cloned and characterized a bifunctional glyoxylate cycle enzyme from E. gracilis (EgGCE). This enzyme consists of an N-terminal malate synthase (MS) domain fused to a C-terminal isocitrate lyase (ICL) domain in a single polypeptide chain. This domain order is inverted compared to the bifunctional glyoxylate cycle enzyme in Caenorhabditis elegans, an N-terminal ICL domain fused to a C-terminal MS domain. Purified EgGCE catalyzed the sequential ICL and MS reactions. ICL activity of purified EgGCE increased in the existence of acetyl-CoA at a concentration of micro-molar order. We discussed the physiological roles of the bifunctional glyoxylate cycle enzyme in these organisms as well as its molecular evolution.
Nakazawa
Masami
M
Department of Applied Biological Chemistry, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan. mami@biochem.osakafu-u.ac.jp
Minami
Tomomi
T
Teramura
Koji
K
Kumamoto
Shohei
S
Hanato
Sayaka
S
Takenaka
Shigeo
S
Ueda
Mitsuhiro
M
Inui
Hiroshi
H
Nakano
Yoshihisa
Y
Miyatake
Kazutaka
K
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000201:enzymology; D002384:Catalysis; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D000431:Ethanol / Q000008:administration & dosage; D005056:Euglena gracilis / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007522:Isocitrate Lyase / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D007700:Kinetics; D008292:Malate Synthase / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D000431:Ethanol; D008292:Malate Synthase; D007522:Isocitrate Lyase