(a) Application as filed
80 The specification of the application as filed is entitled "Process for the production of polyunsaturated fatty acids in transgenic organisms".
81 The specification commences (p 1 lines 5 to 13) with the following description of the field of the invention:
The present invention relates to polynucleotides from Ostreococcus lucimarinus which code for desaturases and elongases and which can be employed for the recombinant production of polyunsaturated fatty acids. The invention furthermore relates to vectors, host cells and transgenic nonhuman organisms which comprise the polynucleotides, and to the polypeptides encoded by the polynucleotides. Finally, the invention also relates to production processes for the polyunsaturated fatty acids and for oil, lipid and fatty acid compositions.
82 Ostreococcus lucimarinus (O. lucimarinus) is a species of unicellular algae.
83 Various health benefits of PUFAs (e.g. brain development and function; eye function; cholesterol levels; arthritis) are described (p 1, line 23 to p 3, line 4).
84 It is explained (p 1 lines 15 to 30):
Fatty acids and triacylglycerides have a multiplicity of applications in the food industry, in animal nutrition, in cosmetics and in the pharmacological sector. Depending on whether they are free saturated or unsaturated fatty acids or else triacylglycerides with an elevated content of saturated or unsaturated fatty acids, they are suitable for very different applications. Polyunsaturated fatty acids such as linoleic acid and linolenic acid are essential for mammals, since they cannot be produced by the latter. Polyunsaturated ω3-fatty acids and ω6-fatty acids are therefore an important constituent in animal and human nutrition.
Polyunsaturated long-chain ω3-fatty acids such as eicosapentaenoic acid (= EPA, C20:5Δ5,8,11,14,17) or docosahexaenoic acid (= DHA, C22:6Δ4,7,10,13,16,19) are important components in human nutrition owing to their various roles in health aspects, including the development of the child brain, the functionality of the eyes, the synthesis of hormones and other signal substances, and the prevention of cardiovascular disorders, cancer and diabetes (Poulos, A Lipids 30:1-14, 1995; Horrocks, LA and Yeo YK Pharmacol Res 40:211-225, 1999). This is why there is a demand for the production of polyunsaturated long-chain fatty acids.
85 At page 2, lines 8 to 19 the specification explains that LC-PUFAs, such as EPA, DHA, AA (ARA) and DPA are conventionally obtained from fish and not synthesised in oil producing crops. The following is said:
The various fatty acids and triglycerides are mainly obtained from microorganisms such as Mortierella and Schizochytrium or from oil-producing plants such as soybean, oilseed rape, algae such as Crypthecodinium or Phaeodactylum and others, where they are obtained, as a rule, in the form of their triacylglycerides (= triglycerides = triglycerols). However, they can also be obtained from animals, such as, for example, fish. The free fatty acids are advantageously prepared by hydrolysis. Very long-chain polyunsaturated fatty acids such as DHA, EPA, arachidonic acid (=ARA, C20:4Δ5,8,11,14), dihomo-γ-linolenic acid (C20:3Δ8,11,14) or docosapentaenoic acid (DPA, C22:5Δ7,10,13,16,19) are not synthesized in oil crops such as oilseed rape, soybean, sunflower or safflower. Conventional natural sources of these fatty acids are fish such as herring, salmon, sardine, redfish, eel, carp, trout, halibut, mackerel, zander or tuna, or algae.
86 The specification acknowledges that, "there has been no lack of attempts in the past to make available genes which are involved in the synthesis of fatty acids or triglycerides for the production of oils in various organisms …" (p 3 lines 5 to 7). Such prior art is then described (p 3, line 8 to p 4, line 26).
87 It is then explained (p 4 line 27 to p 5 line 12):
Depending on their desaturation pattern, the polyunsaturated fatty acids can be divided into two large classes, viz. ω6- or ω3-fatty acids, which differ with regard to their metabolic and functional activities.
The starting material for the ω6-metabolic pathway is the fatty acid linoleic acid (18:2Δ9,12) while the ω3-pathway proceeds via linolenic acid (18:3Δ9,12,15). Linolenic acid is formed by the activity of an ω3-desaturase (Tocher et al. 1998, Prog. Lipid Res. 37, 73-117; Domergue et al. 2002, Eur. J. Biochem. 269, 4105-4113).
Mammals, and thus also humans, have no corresponding desaturase activity (Δ12- and ω3-desaturase) and must take up these fatty acids (essential fatty acids) via the food. Starting with these precursors, the physiologically important polyunsaturated fatty acids arachidonic acid (= ARA, 20:4Δ5,8,11,14), an ω6-fatty acid and the two ω3-fatty acids eicosapentaenoic acid (= EPA, 20:5Δ5,8,11,14,17) and docosahexaenoic acid (DHA, 22:6Δ4·7,10,13,17,19) are synthesized via the sequence of desaturase and elongase reactions. The application of ω3-fatty acids shows the therapeutic activity described above in the treatment of cardiovascular diseases (Shimikawa 2001, World Rev. Nutr. Diet. 88, 100-108), inflammations (Calder 2002, Proc. Nutr. Soc. 61, 345-358) and arthritis (Cleland and James 2000, J. Rheumatol. 27, 2305-2307).
88 The specification identifies that it would be advantageous to introduce genes that encode for the enzymes for LC-PUFA biosynthesis in higher plants (p 6 lines 9 to 16):
To this end, it is advantageous to introduce, into oil crops, genes which encode enzymes of the LCPUFA biosynthesis via recombinant methods and to express them therein. These genes encode for example Δ6-desaturases, Δ6-elongases, Δ5-desaturases or Δ4-desaturases. These genes can advantageously be isolated from microorganisms and lower plants which produce LCPUFAs and incorporate them in the membranes or triacylglycerides. Thus, it has already been possible to isolate Δ6-desaturase genes from the moss Physcomitrella patens and Δ6-elongase genes from P. patens and from the nematode C. elegans.
89 The specification acknowledges that such plants, comprising and expressing genes encoding the enzymes necessary for LC-PUFA biosynthesis, have been described in the prior art (p 6 lines 18 to 22), but that they produce LC-PUFAs in "amounts which require further optimization for processing the oils which are present in the plants".
90 The object of the invention is then stated (p 6, lines 24 to 30):
To make possible the fortification of food and of feed with these polyunsaturated fatty acids, there is therefore a great need for means and measures for a simple inexpensive production of these polyunsaturated fatty acids, specifically in eukaryotic systems. The object of the present invention would therefore be the provision of such means and measures. This object is achieved by the use forms which are described in the patent claims and hereinbelow.
91 The invention the subject of the application is then discussed (p 6 line 31 to p 7 line 2):
The invention, the subject of the present application, is directed to the following:
• a CoA-dependent delta-6-desaturase having the substrate specificity of the delta-6-desaturase shown in SEQ ID NO:14, and
• the above CoA-dependent delta-6-desaturase which has a preference for conversion of alpha linolenic acid compared to linoleic acid.
92 As this passage spans pp 6 and 7 of the application as filed, it has been referred to by the experts as the bridging paragraph. I will also use that description.
93 "CoA-dependent" describes a Δ6-desaturase that predominantly desaturates acyl-Coenzyme A (CoA) bound fatty acid substrates in the cytosolic acyl-CoA pool. SEQ ID NO: 13 is the polynucleotide which encodes the Δ6-desaturase from O. lucimarinus. SEQ ID NO: 14 is the polypeptide sequence encoded by SEQ ID NO: 13, that is, the CoA-dependent Δ6-desaturase polypeptide from O. lucimarinus. Of course, similar polynucleotides may either code for the same polypeptide or for a polypeptide with a similar sequence that preserves the identified biological function of interest. But of course, they may not.
94 As I have said, a substrate is the starting molecule upon which an enzyme acts. An enzyme may bind to and convert multiple substrates. Substrate specificity means the specific substrates, or the number of molecules, that an enzyme binds to at the catalytic site. There is a dispute as to the meaning of "the substrate specificity of the Δ6-desaturase shown in SEQ ID NO: 14".
95 The experts have agreed that the words "the above" mean that the statement in the second bullet point of the bridging paragraph must be read together with the statement in the first bullet point of the bridging paragraph. Further, the feature in the first bullet point does not need to include the ALA preference feature disclosed in the second bullet point.
96 The conversion preference referred to means that the CoA-dependent Δ6 desaturase has greater desaturase activity on ALA relative to LA, that is it preferentially converts ALA to SDA over converting LA to GLA.
97 The experts have agreed that the bridging paragraph is the only place in which a conversion preference for ALA or, indeed, any conversion preference is disclosed in the body of the specification of the application as filed. Moreover, they have agreed that it is only disclosed in the limited context of, and as a feature of, a CoA-dependent Δ6-desaturase having the substrate specificity of the Δ6-desaturase shown in SEQ ID NO: 14.
98 The invention described in the bridging paragraph is specifically claimed in claims 1 and 2 respectively of the application as filed.
99 Page 7, lines 4 to 18 of the application as filed then describe a number of matters "[a]ccording to the invention…". This provides:
According to the invention, the term "polynucleotide" relates to polynucleotides which comprise nucleic acid sequences which code for polypeptides with desaturase or elongase activity. The desaturase or elongase activities are preferably required for the biosynthesis of lipids or fatty acids. Especially preferably, they take the form of the following desaturase or elongase activities: Δ4-desaturase, Δ5-desaturase, Δ5-elongase, Δ6-desaturase, Δ6-elongase or Δ12-desaturase. The desaturases and/or elongases are preferably involved in the synthesis of polyunsaturated fatty acids (PUFAs) and especially preferably in the synthesis of long-chain PUFAs (LCPUFAs). Suitable detection systems for these desaturase or elongase activities are described in the examples or in WO2005/083053. Especially preferably, the above-mentioned activities are, as regards substrate specificities and conversion rates, those of the respective enzymes from Ostreococcus lucimarinus. The specific polynucleotides according to the invention, i.e. the polynucleotides with a nucleic acid sequence as shown in SEQ ID NO: 1, 3, 5, 7, 9, 11, 13 or 15, were obtained from Ostreococcus lucimarinus.
100 Various desaturases and elongases, including Δ4-desaturase activity, Δ5-desaturase activity, Δ5-elongase activity, Δ6-desaturase activity, Δ6-elongase activity or Δ12-desaturase activity, are described. As indicated, it concludes:
Especially preferably, the above-mentioned activities are, as regards substrate specificities and conversion rates, those of the respective enzymes from Ostreococcus lucimarinus.
101 But in dealing with Δ6 desaturases, relevantly this is to be read in the context of the bridging paragraph.
102 The specification then states on p 7 line 20 and p 8 lines 15 to 20:
Therefore, polynucleotides according to the invention are in particular:
…
Polynucleotides which code for a polypeptide with Δ6-desasturase activity and which (i) comprise a nucleic acid sequence as shown in SEQ ID NO:13, (ii) comprise a nucleic acid sequence which codes for a polypeptide as shown in SEQ ID NO:14, (iii) comprise a nucleic acid sequence with at least 72% identity to one of the nucleic acid sequences of (i) or (ii), or (iv) a nucleic acid sequence of a fragment of a nucleic acid from (i), (ii) or (iii).
103 For convenience, and as the experts have done, I will refer to this as the page 8 paragraph.
104 The page 8 paragraph broadly describes polynucleotides which encode a polypeptide having Δ6-desaturase activity. According to the sequence listing, SEQ ID NO: 13 is a polynucleotide which encodes the Δ6-desaturase from O. lucimarinus. From a visual comparison, it would seem that SEQ ID NO: 14 is the polypeptide sequence encoded by SEQ ID NO: 13.
105 Sub-paragraph (i) of the page 8 paragraph provides for polynucleotides that incorporate SEQ ID NO: 13 and which code for a polypeptide having Δ6-desaturase activity.
106 Sub-paragraph (ii) provides for polynucleotides which code for a polypeptide having the amino acid sequence of SEQ ID NO: 14, which is a sequence that has Δ6-desaturase activity. But there would be a pool of polynucleotide sequences that could encode for a protein that has the activity of the protein of SEQ ID NO: 14, given the redundancy in the genetic code.
107 Sub-paragraph (iii) provides for polynucleotides which code for a polypeptide having Δ6-desaturase activity and which have at least 72% identity to those sequences of sub-paragraphs (i) or (ii). Percentage identity would be determined by performing a polynucleotide sequence alignment. On its face this provides for a broader range of polynucleotides than in (i) and (ii).
108 Finally, sub-paragraph (iv) provides for polynucleotides which code for a polypeptide having Δ6-desaturase activity, but which comprise only a fragment of the sequences of (i), (ii) or (iii). This is also on its face a broader range of polynucleotides than in (i) and (ii).
109 In summary, sub-paragraphs (iii) and (iv) of the page 8 paragraph describe a broader range of polynucleotides than sub-paragraphs (i) and (ii) and the polypeptide that is coded for may have a range of differing properties. Now although the experts agree that, taken in isolation, the polynucleotide described at (iii) may not have the substrate specificity of the CoA-dependent Δ6-desaturase shown in SEQ ID NO: 14 or the relevant conversion preference as described in the bridging paragraph, in my view the descriptions at page 7, line 13 and in the page 8 paragraph should be read in the context of the invention disclosed in the bridging paragraph. That is, read as a whole, the polynucleotides described in the page 8 paragraph are examples of polynucleotides coding for the invention described in the bridging paragraph.
110 Further, the invention is also said to relate to a process for the production of a substance which has the formula shown on pages 38 to 39. The formula covers an enormous array of chemical compounds and LC-PUFAs. This aspect of the invention is claimed in dependent claim 9 of the application as filed.
111 Figures 1 to 5 of the specification compare, respectively, the sequence alignment of Δ5- and Δ6-elongase, Δ4-desaturase, Δ5-desaturase, Δ6-desaturase and Δ12-desaturase amino acid sequences from O. lucimarinus and other unicellular algae (p 64 lines 5 to 20). Figure 4 relates to Δ6-desaturase.
112 Figures 6 to 10 show gas-chromatographic determination of fatty acids from yeasts which have been transformed with various plasmids (p 64 line 21 to p 65 line 5).
113 The specification concludes with five examples of "the present invention" (p 65 lines 7 and 8). Examples 1 to 3 relate to general methods of cloning, sequence analysis and lipid extraction. Example 4 relates to cloning and characterisation of elongase genes from O. lucimarinus. Example 5 relates to cloning and characterisation of desaturase genes from O. lucimarinus. Δ6-desaturase with SEQ ID No: 14 (this did refer to SEQ ID No: 30 in the application as filed but "30" has now been corrected to "14") is characterised and its sequence similarity is compared to Δ6 desaturases from other algae (p 72 line 15 to p 74 line 26). But the activity and substrate specificity is only provided for two Δ5-desaturases and a Δ12-desaturase and not the Δ6 desaturase (pp 74 to 77).
114 The application as filed ends in 15 claims. Claim 1 is the only independent claim. Claims 2 to 8 are product claims that depend on claim 1. Claims 9 to 11 are process claims that ultimately depend on claim 1. Claims 12 to 14 are use claims that ultimately depend on claim 1. Claim 15 is a product by process claim, dependent on claims 9 to 11.
115 Claim 1 of the application as filed is for:
A CoA-dependent delta-6 desaturase having the substrate specificity of the delta-6 desaturase shown in SEQ ID NO: 14.
116 For convenience, and as the CSIRO has submitted, the "substrate specificity of the delta-6 desaturase shown in SEQ ID NO: 14" can be referred to as feature A. It is stipulated in the first bullet point of the bridging paragraph.
117 Dependent claim 2 of the application as filed is for:
The CoA-dependent delta-6 desaturase according to claim 1, wherein the desaturase has a preference for conversion of alpha linolenic acid compared to linoleic acid.
118 Again for convenience, a "preference for conversion of alpha linolenic acid compared to linoleic acid" can be referred to as feature B. It is stipulated in the second bullet point of the bridging paragraph. Accordingly, dependent claim 2 of the application as filed is for a CoA-dependent Δ6-desaturase having both feature A and feature B.
119 Dependent claim 3 of the application as filed is for:
An isolated polynucleotide comprising a nucleic acid sequence coding for the CoA-dependent Delta-6 desaturase according to claim 1.
120 Dependent claim 5 of the application as filed is relevantly for:
A host cell comprising the polynucleotide according to claim 3…
121 Dependent claim 9 of the application as filed is for:
A process for the production of a substance which has the structure shown in the general formula I hereinbelow:
where the variables and substituents are as follows:
R1 = hydroxyl, coenzyme A (thioester), lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylglycerol, lysodiphosphatidylglycerol, lysophosphatidylserine, lysophosphatidylinositol, sphingo base or a radical of the formula II
R2 = hydrogen, lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylglycerol, lysodiphosphatidylglycerol, lysophosphatidylserine, lysophosphatidylinositol or saturated or unsaturated C2-C24-alkylcarbonyl,
R3 = hydrogen, saturated or unsaturated C2-C24-alkylcarbonyl, or R2 and R3 independently of one another are a radical of the formula Ia:
n = 2, 3, 4, 5, 6, 7 or 9, m = 2, 3, 4, 5 or 6 and p = 0 or 3;
and
wherein the process comprises the cultivation of (i) a host cell according to claim 5 or (ii) of a transgenic, nonhuman organism according to claim 7 or claim 8, under conditions which permit the biosynthesis of the substance.
122 A transgenic, nonhuman organism according to claim 7 or claim 8 is one which, inter-alia, comprises an isolated polynucleotide according to claim 3.
123 Dependent claim 12 of the application as filed is for the use of the polynucleotide, or a vector, host cell, transgenic, nonhuman organism comprising the polynucleotide, according to claim 3, for the production of an oil, lipid or fatty acid composition.
124 Finally, it is to be noted that no claim of the application as filed is dependent on claim 2. Further, the application as filed does not claim a process or use that relates to a CoA-dependent Δ6-desaturase having both features A and B. Claim 2 claims a product, being a CoA-dependent Δ6-desaturase having both features.