title: Acyl-ACP thioesterases from Camelina sativa: cloning, enzymatic characterization and implication in seed oil fatty acid composition.
abstract: Acyl-acyl carrier protein (ACP) thioesterases are intraplastidial enzymes that terminate de novo fatty acid biosynthesis in the plastids of higher plants by hydrolyzing the thioester bond between ACP and the fatty acid synthesized. Free fatty acids are then esterified with coenzyme A prior to being incorporated into the glycerolipids synthesized through the eukaryotic pathway. Acyl-ACP thioesterases belong to the TE14 family of thioester-active enzymes and can be classified as FatAs and FatBs, which differ in their amino acid sequence and substrate specificity. Here, the FatA and FatB thioesterases from Camelina sativa seeds, a crop of interest in plant biotechnology, were cloned, sequenced and characterized. The mature proteins encoded by these genes were characterized biochemically after they were heterologously expressed in Escherichia coli and purified. C. sativa contained three different alleles of both the FatA and FatB genes. These genes were expressed most strongly in expanding tissues in which lipids are very actively synthesized, such as developing seed endosperm. The CsFatA enzyme displayed high catalytic efficiency on oleoyl-ACP and CsFatB acted efficiently on palmitoyl-ACP. The contribution of these two enzymes to the synthesis of C. sativa oil was discussed in the light of these results.
authors.affiliation: Instituto de la Grasa, CSIC, Avda Padre García Tejero 4, 41012 Seville, Spain.
authors.forename: Manuel Fernando
authors.initials: MF
authors.lastname: Rodríguez-Rodríguez
authors.affiliation: Instituto de la Grasa, CSIC, Avda Padre García Tejero 4, 41012 Seville, Spain. Electronic address: emforce@ig.csic.es.
authors.forename: Joaquín J
authors.initials: JJ
authors.lastname: Salas
authors.affiliation: Instituto de la Grasa, CSIC, Avda Padre García Tejero 4, 41012 Seville, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Garcés
authors.affiliation: Instituto de la Grasa, CSIC, Avda Padre García Tejero 4, 41012 Seville, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Martínez-Force
mesh_terms: D000213:Acyl Carrier Protein / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D019607:Brassicaceae / Q000201:enzymology*; D004926:Escherichia coli / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis* / Q000096:biosynthesis / Q000378:metabolism; D010938:Plant Oils / Q000378:metabolism*; D010944:Plants / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012639:Seeds / Q000737:chemistry*; D013379:Substrate Specificity; D013869:Thiolester Hydrolases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000213:Acyl Carrier Protein; D005227:Fatty Acids; D010938:Plant Oils; D013869:Thiolester Hydrolases; C018748:oleoyl-(acyl-carrier-protein) hydrolase
keywords: Acyl-ACP thioesterases; Camelina sativa; FatA; FatB; Fatty acid bio-synthesis