A lipoxygenase with dual positional specificity is expressed in olives (Olea europaea L.) during ripening.
Plant lipoxygenases (LOXs) are a class of widespread dioxygenases catalysing the hydroperoxidation of polyunsaturated fatty acids. Although multiple isoforms of LOX have been detected in a wide range of plants, their physiological roles remain to be clarified. With the aim to clarify the occurrence of LOXs in olives and their contribution to the elaboration of the olive oil aroma, we cloned and characterized the first cDNA of the LOX isoform which is expressed during olive development. The open reading frame encodes a polypeptide of 864 amino acids. This olive LOX is a type-1 LOX which shows a high degree of identity at the peptide level towards hazelnut (77.3%), tobacco (76.3%) and almond (75.5%) LOXs. The recombinant enzyme shows a dual positional specificity, as it forms both 9- and 13-hydroperoxide of linoleic acid in a 2:1 ratio, and would be defined as 9/13-LOX. Although a LOX activity was detected throughout the olive development, the 9/13-LOX is mainly expressed at late developmental stages. Our data suggest that there are at least two Lox genes expressed in black olives, and that the 9/13-LOX is associated with the ripening and senescence processes. However, due to its dual positional specificity and its expression pattern, its contribution to the elaboration of the olive oil aroma might be considered.
Palmieri-Thiers
Cynthia
C
Université de Corse, CNRS UMR6134 SPE, Laboratoire de Biochimie et Biologie Moléculaire Végétales, campus Grimaldi, BP52, 20250 Corte, France.
Canaan
Stéphane
S
Brunini
Virginie
V
Lorenzi
Vannina
V
Tomi
Félix
F
Desseyn
Jean-Luc
JL
Garscha
Ulrike
U
Oliw
Ernst H
EH
Berti
Liliane
L
Maury
Jacques
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D002851:Chromatography, High Pressure Liquid; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005638:Fruit / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D007700:Kinetics; D008084:Lipoxygenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D031658:Olea / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D011110:Polymorphism, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
D018076:DNA, Complementary; D011994:Recombinant Proteins; D008084:Lipoxygenase