Characterization of a methyljasmonate-inducible lipoxygenase from barley (Hordeum vulgare cv. Salome) leaves.
We found three methyl jasmonate-induced lipoxygenases with molecular masses of 92 kDa, 98 kDa, and 100 kDa (LOX-92, -98 and -100) [Feussner, I., Hause, B., Vörös, K., Parthier, B. & Wasternack, C. (1995) Plant J. 7, 949-957]. At least two of them (LOX-92 and LOX-100), were shown to be localized within chloroplasts of barley leaves. Here, we describe the isolation of a cDNA (3073 bp) coding for LOX-100, a protein of 936 amino acid residues and a molecular mass of 106 kDa. By sequence comparison this lipoxygenase could be identified as LOX2-type lipoxygenase and was therefore designated LOX2:Hv:1. The recombinant lipoxygenase was expressed in Escherichia coli and characterized as linoleate 13-LOX and arachidonate 15-LOX, respectively. The enzyme exhibited a pH optimum around pH 7.0 and a moderate substrate preference for linoleic acid. The gene was transiently expressed after exogenous application of jasmonic acid methyl ester with a maximum between 12 h and 18 h. Its expression was not affected by exogenous application of abscisic acid. Also a rise of endogenous jasmonic acid resulting from sorbitol stress did not induce LOX2:Hv:1, suggesting a separate signalling pathway compared with other jasmonate-induced proteins of barley. The properties of LOX2:Hv:1 are discussed in relation to its possible involvement in jasmonic acid biosynthesis and other LOX forms of barley identified so far.
Vörös
K
K
Institut für Pflanzenbiochemie, Halle, Germany.
Feussner
I
I
Kühn
H
H
Lee
J
J
Graner
A
A
Löbler
M
M
Parthier
B
B
Wasternack
C
C
D000085:Acetates / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003517:Cyclopentanes / Q000494:pharmacology*; D018076:DNA, Complementary / Q000302:isolation & purification; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D001467:Hordeum / Q000201:enzymology*; D008084:Lipoxygenase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D054883:Oxylipins; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000201:enzymology; D017422:Sequence Analysis, DNA; D013012:Sorbitol / Q000494:pharmacology
D000085:Acetates; D003517:Cyclopentanes; D018076:DNA, Complementary; D054883:Oxylipins; D010937:Plant Growth Regulators; D013012:Sorbitol; C072239:methyl jasmonate; D008084:Lipoxygenase