Mitochondrial fatty acid synthesis type II: more than just fatty acids.
Eukaryotes harbor a highly conserved mitochondrial pathway for fatty acid synthesis (FAS), which is completely independent of the eukaryotic cytosolic FAS apparatus. The activities of the mitochondrial FAS system are catalyzed by soluble enzymes, and the pathway thus resembles its prokaryotic counterparts. Except for octanoic acid, which is the direct precursor for lipoic acid synthesis, other end products and functions of the mitochondrial FAS pathway are still largely enigmatic. In addition to low cellular levels of lipoic acid, disruption of genes encoding mitochondrial FAS enzymes in yeast results in a respiratory-deficient phenotype and small rudimentary mitochondria. Recently, two distinct links between mitochondrial FAS and RNA processing have been discovered in vertebrates and yeast, respectively. In vertebrates, the mitochondrial 3-hydroxyacyl-acyl carrier protein dehydratase and the RPP14 subunit of RNase P are encoded by the same bicistronic transcript in an evolutionarily conserved arrangement that is unusual for eukaryotes. In yeast, defects in mitochondrial FAS result in inefficient RNase P cleavage in the organelle. The intersection of mitochondrial FAS and RNA metabolism in both systems provides a novel mechanism for the coordination of intermediary metabolism in eukaryotic cells.
Hiltunen
J Kalervo
JK
Department of Biochemistry and Biocenter Oulu, University of Oulu, FI-90014 Oulu, Finland. kalervo.hiltunen@oulu.fi
Schonauer
Melissa S
MS
Autio
Kaija J
KJ
Mittelmeier
Telsa M
TM
Kastaniotis
Alexander J
AJ
Dieckmann
Carol L
CL
D000818:Animals; D005227:Fatty Acids / Q000096:biosynthesis*; D008040:Genetic Linkage / Q000235:genetics; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D012343:RNA, Transfer / Q000235:genetics; D043262:Ribonuclease P / Q000378:metabolism; D008063:Thioctic Acid / Q000096:biosynthesis
D005227:Fatty Acids; D008063:Thioctic Acid; D012343:RNA, Transfer; D043262:Ribonuclease P