IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
artículos
Título:
Biosynthesis of polyunsaturated fatty acids in lower eukaryotes
Autor/es:
A. D. UTTARO
Revista:
IUBMB LIFE
Referencias:
Año: 2006 vol. 58 p. 563 - 571
ISSN:
1521-6543
Resumen:
Polyunsaturated fatty acids have important structural roles in
cell membranes. They are also intermediates in the synthesis of
biologically active molecules such as eicosanoids, which mediate
fever, inflammation, blood pressure and neurotransmission. Arachidonic
and docosahexaenoic acids are essential components of brain
tissues and, through their involvement in the development of neural
and retinal functions, important dietary nutrients for neonatal
babies. Lower eukaryotes are particularly rich in C20-22 polyunsaturated
fatty acids. Fungi and marine microalgae are currently
used to produce nutraceutic oils. Other protists and algae are being
studied because of the variability in their enzymes involved in
polyunsaturated fatty acid biosynthesis. Such enzymes could be used
as source for the production of transgenic organisms able to
synthesize designed oils for human diet or, in the case of parasitic
protozoa, they might be identified as putative chemotherapeutic
targets. Polyunsaturated fatty acids can be synthesized by two
different pathways: an anaerobic one, by using polyketide synthase
related enzymes, and an aerobic one, which involves the action of
elongases and oxygen dependent desaturases. Desaturases can be
classified into three main types, depending on which of the consecutive
steps of polyunsaturated fatty acid synthesis they are
involved with. The enzymes may be specialized to act on: saturated
substrates (type I); mono- and di-unsaturated fatty acids by
introducing additional double bonds at the methyl-end site of the
existing double bonds (type II); or the carboxy half (front-end) of
polyunsaturated ones (type III). Type III desaturases require the
alternating action of elongases. A description of the enzymes that
have been isolated and functionally characterized is provided, in
order to highlight the different pathways found in lower eukaryotes.