PUFA Polyketide Synthase Systems and Uses Thereof

Abstract

Disclosed are the complete polyunsaturated fatty acid (PUFA) polyketide synthase (PKS) systems from Schizochytrium , and biologically active fragments and homologues thereof. More particularly, this invention relates to nucleic acids encoding such PUFA PKS systems, to proteins and domains thereof that comprise such PUFA PKS systems, to genetically modified organisms (plants and microorganisms) comprising such PUFA PKS systems, and to methods of making and using the PUFA PKS systems disclosed herein. This invention also relates to genetically modified plants and microorganisms and methods to efficiently produce lipids enriched in various polyunsaturated fatty acids (PUFAs) as well as other bioactive molecules by manipulation of a PUFA polyketide synthase (PKS) system.

1 - 16 . (canceled) 
     
     
         17 . An isolated nucleic acid molecule comprising a nucleic acid sequence selected from the group consisting of:
 a) a nucleic acid sequence of SEQ ID NO:29;   b) a nucleic acid sequence encoding an amino acid sequence of SEQ ID NO:30; and   c) a nucleic acid sequence encoding an amino acid sequence that is at least 90% identical to SEQ ID NO:30 or that is a fragment of SEQ ID NO:30, wherein the amino acid sequence has FabA-like β-hydroxy acyl-ACP dehydrase (DH) activity, and wherein said amino acid sequence comprises the sequence of H-G-I-A-N-P-T-F-V-H-A-P-G-K-I (positions 876-890 of SEQ ID NO:6) at positions corresponding to amino acids 426-440 of SEQ ID NO:30.   
     
     
         18 - 45 . (canceled) 
     
     
         46 . A plant or a part of the plant, wherein the total fatty acid profile in the plant or part of the plant comprises detectable amounts of DHA (docosahexaenoic acid (C22:6, n-3)) and DPA (docosapentaenoic acid (C22:5, n 6). 
     
     
         47 . The plant or a part of the plant of  claim 46 , wherein the ratio of DPAn-6 to DHA is less than 1:1. 
     
     
         48 . The plant or a part of the plant of  claim 46 , wherein the total fatty acid profile in the plant or part of the plant contains less than 5% by weight in total of all of the following PUFAs: gamma-linolenic acid (GLA; 18:3, n-6), PUFAs having 18 carbons and four carbon-carbon double bonds, PUFAs having 20 carbons and three carbon-carbon double bonds, and PUFAs having 22 carbons and two or three carbon-carbon double bonds. 
     
     
         49 . The plant or a part of the plant of  claim 46 , wherein the total fatty acid profile in the plant or part of the plant comprises at least about 0.5% by weight of at least one polyunsaturated fatty acid (PUFA) selected from the group consisting of DHA (C22:6n-3) and DPAn-6 (C22:5n-6), and wherein the total fatty acid profile in the plant or part of the plant contains less than 5% in total of all of the following PUFAs: gamma-linolenic acid (GLA; 18:3, n-6), PUFAs having 18 carbons and four carbon-carbon double bonds, PUFAs having 20 carbons and three carbon-carbon double bonds, and PUFAs having 22 carbons and two or three carbon-carbon double bonds. 
     
     
         50 . The plant or a part of the plant of  claim 46 , wherein the total fatty acid profile in the plant or part of the plant comprises at least about 0.5% by weight of at least one polyunsaturated fatty acid (PUFA) selected from the group consisting of DHA (C22:6n-3) and DPAn-6 (C22:5n-6), and wherein the total fatty acid profile in the plant or part of the plant contains PUFAs having 18 carbons and four carbon-carbon double bonds, PUFAs having 20 carbons and three carbon-carbon double bonds, and PUFAs having 22 carbons and two or three carbon-carbon double bonds. 
     
     
         51 . The plant or a part of the plant of  claim 46 , wherein the total fatty acid profile in the plant or part of the plant comprises at least about 0.5% by weight of at least one polyunsaturated fatty acid (PUFA) selected from the group consisting of DHA (C22:6n-3) and DPAn-6 (C22:5n-6), and wherein the total fatty acid profile in the plant or part of the plant contains less than 2% of gamma-linolenic acid (GLA; 18:3, n-6) and dihomo-gamma-linolenic acid (DGLA or HGLA; 20:3, n-6). 
     
     
         52 . Seeds obtained from the plant or part of the plant of  claim 46 . 
     
     
         53 . A food product comprising the seeds of  claim 52 . 
     
     
         54 . An oil obtained from seeds of the plant of  claim 46  any. 
     
     
         55 . A food product comprising the oil of  claim 54 . 
     
     
         56 . An oil blend comprising the oil of  claim 54  and another oil. 
     
     
         57 - 59 . (canceled) 
     
     
         60 . The oil of  claim 54 , comprising the following fatty acids: DHA (C22:6n-3), DPAn-6 (C22:5n-6), oleic acid (C18:1), linolenic acid (C18:3), linoleic acid (C18:2), C16:0, C18:0, C20:0, C20:1n-9, C20:2n-6, C22:1n-9; wherein the oil comprises less than 0.5% of any of the following fatty acids: gamma-linolenic acid (GLA; 18:3, n-6), PUFAs having 18 carbons and four carbon-carbon double bonds, PUFAs having 20 carbons and three carbon-carbon double bonds, and PUFAs having 22 carbons and two or three carbon-carbon double bonds. 
     
     
         61 - 66 . (canceled) 
     
     
         67 . The plant or a part of the plant of  claim 46 , wherein the ratio of DPAn-6 to DHA is 1:1 or greater than 1:1.