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Cloning and functional characterisation of an enzyme involved in the elongation of Δ6‐polyunsaturated fatty acids from the moss Physcomitrella patens
Author(s) -
Zank Thorsten K.,
Zähringer Ulrich,
Beckmann Christoph,
Pohnert Georg,
Boland Wilhelm,
Holtorf Hauke,
Reski Ralf,
Lerchl Jens,
Heinz Ernst
Publication year - 2002
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2002.01354.x
Subject(s) - physcomitrella patens , polyunsaturated fatty acid , biochemistry , cerulenin , saccharomyces cerevisiae , biology , complementary dna , yeast , fatty acid , enzyme , gene , mutant , fatty acid synthase
Summary The moss Physcomitrella patens contains high proportions of polyunsaturated very‐long‐chain fatty acids with up to 20 carbon atoms. Starting from preformed C 18 polyunsaturated fatty acids, their biosynthesis involves a sequence of Δ6‐desaturation, Δ6‐elongation and Δ5‐desaturation. In this report we describe for the first time the characterisation of a cDNA ( PSE1 ) of plant origin with homology to the ELO‐genes from Saccharomyces cerevisiae , encoding a component of the Δ6‐elongase. Functional expression of PSE1 in S. cerevisiae led to the elongation of exogenously supplied Δ6‐polyunsaturated fatty acids. By feeding experiments with different trienoic fatty acids of natural and synthetic origin, both substrate specificity and substrate selectivity of the enzyme were investigated. The activity of Pse1, when expressed in yeast, was not sensitive to the antibiotic cerulenin, which is an effective inhibitor of fatty acid synthesis and elongation. Furthermore, the PSE1 gene was disrupted in the moss by homologous recombination. This led to a complete loss of all C 20 polyunsaturated fatty acids providing additional evidence for the function of the cDNA as coding for a component of the Δ6‐elongase. The elimination of the elongase was not accompanied by a visible alteration in the phenotype, indicating that C 20 ‐PUFAs are not essential for viability of the moss under phytotron conditions.