Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1991-04-01
1995-06-13
Wax, Robert A.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
424 93461, 536 234, C12N 1500, C07H 1700, A01N 6300
Patent
active
054244099
DESCRIPTION:
BRIEF SUMMARY
This invention relates to recombinant DNA, and in particular to such DNA coding Bacillus thuringiensis endotoxin.
The organism Bacillus thuringiensis carries genes which encode protein endotoxins which are insecticidal to a variety of agronomically important insects. They are not however harmful to many benign insects, or to earthworms, birds, fish or mammals. These endotoxins are thus useful as agricultural insecticides, particularly against Lepidopteran pests. Bacillus thuringiensis strains have been used as agricultural insecticides for many years.
Recently, Bacillus thuringiensis endotoxin genes have been engineered into dicotyledonous plants and shown to confer protection against insect attack. The Bacillus thuringiensis kurstaki strain, A20, is the subject of our prior unpublished copending UK application No 8730132 filed 24 Dec. 1987. Strain A20 has been deposited at the National Collection of Industrial and Marine Bacteria (NCIMB) at Aberdeen, Scotland on 20 Oct. 1987 under the NCIMB Accession Number 12570. It is more active than the commonly used variety kurstaki strain, HD-1. Strain A20 carries three different, but highly related, endotoxin genes similar to those described in the scientific literature as 6.6-, 5.3-, and 4.5-type genes. The first two genes are carried in one or more copies on plasmids and also on the bacterial chromosome, while the 4.5- type gene is only found on the bacterial chromosome.
According to the present invention we provide recombinant DNA coding for an insecticidally active form of the Bacillus thuringiensis endotoxin which DNA is derived from the A20 strain of Bacillus thuringiensis. The source of the DNA maybe either the chromosome or a plasmid.
In a further aspect, our invention comprises recombinant DNA coding for an insecticidally-active form of the Bacillus thuringiensis endotoxin which is derived from a 6.6-type endotoxin gene carried on a plasmid harboured by strain A20. The maximum molecular weight of such endotoxins is about 103,000 Dalton.
We have made such recombinant DNA comprising the first 2910 basepairs (970 amino acid codons) of the N-terminal coding region of a plasmid-derived 6.6-type endotoxin gene from Strain A20. The 6.6-type construct we have made encodes a fusion protein that includes 28 amino acid codons derived from the pUC19 vector DNA. The Bacillus thuringiensis-derived portion of the recombinant DNA has 10 basepair changes as compared with the analogous plasmid-derived 6.6-type gene from Bacillus thuringiensis strain HD 73 (Adang et al, Gene 36, 1985, 289-300). Surprisingly, all of the base changes occur within the generally conserved N-terminal portion of the gene previously designated as a "highly-conserved" region (Whiteley and Schnepf, Ann. Rev. Microbiol., 40, 1986, pp549-576). Nine of the ten changes are clustered in a 0.35 kilobase segment which does not overlap with any of the 5 regions shown to be conserved in all types of endotoxin genes analysed to date (Sanchis et al., Molecular Microbiol., 3, 1989, pp229- 238). Four of the 10 base changes result in amino acid substitutions.
The invention further comprises recombinant DNA coding for an insecticidally-active form of the Bacillus thuringiensis endotoxin which is derived from a 5.3-type endotoxin gene carried on a plasmid harboured by strain A20. The maximum molecular weight of the endotoxin is about 78,000 Daltons.
We have made such recombinant DNA comprising the first 2161 basepairs (696 amino acid codons) of the N-terminal coding region of a plasmid-derived 5.3-type endotoxin gene from Strain A20. This endotoxin gene differs from the analogous plasmid-derived 5.3-type gene from Bacillus thuringiensis strain HD-1 (Geiser etal., Gene 48, 1986, pp109-118) in that a deoxyguanosine base present in the published sequence at nucleotide 2024 is not present, resulting in a reading frame shift relative to the published structural gene. This frame shift results in a termination of the endotoxin gene product at amino acid residue 696, within the Bacillus thuringiensis-derived portion of the
REFERENCES:
patent: 5061489 (1991-10-01), Bernier et al.
Chemical Abstracts, vol. 108, No. 21, 23 May 1988. (Columbus, Ohio, US), Hefford, Mary Alice et al: "Sequence of a lepidopteran toxin gene of Bacillus thuringiensis subsp kurstaki NRD-12.", see p. 182, abstract 181175c, & J. Biotechnol. 1987, 6(4), 307-22.
Hofte et al., Appl. Env. Microb., vol. 54, No. 8, Aug. 1988, pp. 2010-2017.
Prefontaine et al., Appl. Env. Microb, vol. 53, No. 12, Dec. 1987, pp. 2808-2814.
Hefford et al., J. Biotech., vol. 6, pp. 307-322, 1987.
Ely Susan
Tippett Janet M.
Hendricks Keith D.
Imperial Chemical Industries plc
Wax Robert A.
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