Claims for Patent: 5,420,032

Summary for Patent: 5,420,032

Title:	Homing endonuclease which originates from chlamydomonas eugametos and recognizes and cleaves a 15, 17 or 19 degenerate double stranded nucleotide sequence
Abstract:	The present invention relates to a homing endonuclease which originates from Chlamydomonas eugametos, and was overproduced in E. coli, purified and characterized. The homing endonuclease of the present invention recognizes and cleaves degenerate double-stranded DNA at a specific recognition site; it particularly recognizes and cleaves 15, 17 and 19 nucleotide sequences. The cleavage of target DNA by this endonuclease produces a 4 nucleotide extension with a 3\' OH overhang. A method to use the endonuclease of the present invention to cleave DNA fragments useful for gene mapping is also disclosed.
Inventor(s):	Marshall; Philip (Chomedey Est, CA), Lemieux; Claude (Quebec, CA), Gauthier; Antonin (Montreal, CA), Turmel; Monique (Quebec, CA)
Assignee:	Universitge Laval (Quebec, CA)
Application Number:	07/991,855
Patent Claims:	1. An isolated endonuclease from Chlamydomonas eugametos which recognizes and cuts at a recognition sequence in a degenerate double-stranded target DNA sequence, wherein said recognition sequence includes the following nucleic acid sequence: ##STR12## and wherein N is T or A and N' is T or A and wherein the staggered line represents where the endonuclease cuts the degenerate double-stranded target DNA sequence. 2. An isolated endonuclease originating from the chloroplast of unicellular green algae Chlamydomonas eugametos which recognizes and cleaves a degenerate double-stranded target DNA sequence, said endonuclease, when encountered in its natural environment, is involved in an intron homing process, said process being defined by the insertion of an intron in an insertion site of a corresponding allele, said insertion involving recognition and cleavage of both strands of a naturally occurring wild-type sequence consisting essentially of at least a part of the following nucleic acid sequence by said endonuclease: ##STR13## wherein said insertion site is represented by the open triangles and the cleavage on both strands is represented by a staggered line; said cleavage being effected by cutting after the fifth nucleotide downstream from said insertion site on the upper strand of said wild-type sequence, and by cutting before the first nucleotide upstream from said insertion site on the lower stand of said wild-type sequence, said downstream direction being the 5'.fwdarw.3' direction and said upstream direction being the 3'.fwdarw.5' direction; said cleavage thereby generating a four nucleotide 3' protruding sequence; said degenerate double-stranded target DNA sharing homology with said wild-type sequence in such a way that said homology still confers recognition and cleavage of said target DNA by said endonuclease with an efficiency of cleavage comprising between about 50 to 100% of the efficiency of cleavage of the corresponding wild-type sequence after a 1 to 16 hour reaction period, at an optimal temperature of 37.degree. C. 3. An endonuclease according to claim 1, wherein N and N' are T and A, respectively. 4. An endonuclease according to claim 2, wherein the degeneracy of said target DNA is defined by base-pair substitutions effected at specific sites on said naturally occurring wild-type target sequence, said target DNA bearing said substitutions still being recognized and cleaved by said endonuclease, with an efficiency of cleavage being comprised between 50% and 100% of cleavage of said wild-type sequence, after a 1 to 16 hour reaction period, at an optimal temperature of 37.degree. C. 5. An endonuclease according to claim 1 which recognizes and cleaves a double-stranded target DNA which nucleic acid sequence is selected from the group consisting of the following nucleic acid sequences: wherein degeneracy of sequence is represented by underlined base-pair substitutions. 6. An endonuclease according to claim 4 which recognizes and cleaves a double-stranded target DNA which nucleic acid sequence is selected from the group consisting of the following nucleic acid sequences: wherein base-pair substitutions are underlined. 7. An endonuclease according to claim 1 which recognizes and cleaves a double-stranded target DNA which nucleic acid sequence is selected from the group consisting of the following nucleic acid sequences: wherein degeneracy of sequence is represented by underlined base-pair substitutions. 8. An endonuclease according to claim 4 which recognizes and cleaves a double-stranded target DNA which nucleic acid sequence is selected from the group consisting of the following nucleic acid sequences: wherein base-pair substitutions are underlined. 9. An endonuclease according to claim 1 which recognizes and cleaves a double-stranded target DNA which nucleic acid sequence is selected from the group consisting of the following nucleic acid sequences: wherein degeneracy of sequence is represented by underlined base-pair substitutions. 10. An endonuclease according to claim 4 which recognizes and cleaves a double-stranded target DNA which nucleic acid sequence is selected from the consisting of the following nucleic acid sequences group: wherein base-pair substitutions are underlined. 11. An endonuclease according to claim 2, wherein said wild-type sequence originates from the chloroplast of unicellular green alga Chlamydomonas moewusii.

Details for Patent 5,420,032

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Merck Sharp & Dohme Corp.	INTRON A	interferon alfa-2b	For Injection	103132	06/04/1986		2012-05-30
Merck Sharp & Dohme Corp.	INTRON A	interferon alfa-2b	For Injection	103132			2012-05-30
Merck Sharp & Dohme Corp.	INTRON A	interferon alfa-2b	Injection	103132			2012-05-30