The present invention relates to a fungal C 16/18 fatty acid elongase that is able to catalyze the conversion of palmitate (16:0) to stearic acid (18:0). Specifically, the nucleotide sequence of a Mortierella alpina C 16/18 fatty acid elongase is provided (designated as “ELO3”). Methods of increasing microbial oil production, increasing carbon flux into the polyunsaturated fatty acid biosynthetic pathway and increasing the content of polyunsaturated fatty acids by over-expression of the C 16/18 fatty acid elongase are described herein. Most desirably, the substrate specificity of the instant ELO3 will be particularly useful to enable accumulation of long-chain polyunsaturated fatty acids in oleaginous yeast, such as Yarrowia lipolytica.
1. An isolated nucleic acid molecule encoding a C 16/18 fatty acid elongase enzyme, selected from the group consisting of:
(a) an isolated nucleic acid molecule encoding the amino acid sequence as set forth in SEQ ID NO:2 and
(b) an isolated nucleic acid molecule that hybridizes with (a) under the following hybridization conditions: 0.1×SSC, 0.1% SDS, 65° C. and washed with 2×SSC, 0.1% SDS followed by 0.1×SSC, 0.1% SDS; or,
an isolated nucleic acid molecule that is completely complementary to (a) or (b).
2. The isolated nucleic acid molecule of claim 1 as set forth in SEQ ID NO: 1.
3. An isolated nucleic acid molecule comprising a first nucleotide sequence encoding a C 16/18 fatty acid elongase enzyme of at least 275 amino acids that has at least 95% identity based on the BLAST method of alignment when compared to a polypeptide having the sequence as set forth in SEQ ID NO:2;
or a second nucleotide sequence comprising the complement of the first nucleotide sequence.
4. A chimeric gene comprising the isolated nucleic acid molecule of claim 1 operably linked to suitable regulatory sequences.
5. An isolated host cell comprising the isolated nucleic acid molecule of claim 1 .
6. The isolated host cell of claim 5 selected from the group consisting of algae, bacteria, fungi and yeast.
7. The transformed host cell of claim 6 wherein the yeast is an oleaginous yeast.
8. The transformed host cell of claim 7 wherein the oleaginous yeast cell is selected from the group consisting of: Yarrowia, Candida,Rhodotorula, Rhodosporidium, Cryptococcus, Trichosporon and Lipomyces.
9. The transformed host cell of claim 8 wherein the host cell is Yarrowia lipolytica.