Acyl-ACP thioesterases from macadamia (Macadamia tetraphylla) nuts: cloning, characterization and their impact on oil composition.
Plant Physiol Biochem
; 49(1): 82-7, 2011 Jan.
Article
in En
| MEDLINE
| ID: mdl-21071236
ABSTRACT
The mechanisms by which macadamia nuts accumulate the unusual palmitoleic and asclepic acyl moieties, which constitute up to 20% of the fatty acids in some varieties, are still unknown. Acyl-acyl carrier protein (ACP) thioesterases (EC 3.1.2.14) are intraplastidial enzymes that terminate the synthesis of fatty acids in plants and that facilitate the export of the acyl moieties to the endoplasmic reticulum where they can be used in the production of glycerolipids. Here, we have investigated the possible role of acyl-ACP thioesterase activity in the composition of macadamia kernel oil. Accordingly, two acyl-ACP thioesterases were cloned from developing macadamia kernels, one of the FatA type and the other of the FatB type. These enzymes were heterologously expressed in Escherichia coli, and the recombinant thioesterases were purified, characterized kinetically and assayed with a variety of substrates, demonstrating the high specificity of macadamia FatA towards 161-ACP. Acyl-ACP thioesterase activity was also characterized in crude extracts from two different varieties of macadamia, Cate and Beaumont, which accumulate different amounts of n-7 fatty acids. The impact of acyl-ACP thioesterase activities on the oil composition of these kernels is discussed in the light of these results.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Thiolester Hydrolases
/
Plant Oils
/
Acyl Carrier Protein
/
Macadamia
/
Fatty Acids
/
Nuts
Language:
En
Journal:
Plant Physiol Biochem
Journal subject:
BIOQUIMICA
/
BOTANICA
Year:
2011
Type:
Article
Affiliation country:
Spain