Michael J Mcclelland

US Patent:

48085251, Feb 28, 1989

Filed:

Sep 11, 1987

Appl. No.:

7/096765

Inventors:

Michael McClelland - New York NY
Louis G. Kessler - Dallas TX

Assignee:

University of Georgia Research Center - Athens GA

International Classification:

C12P 1934
C12P 2100
C07H 1512
C12Q 160

US Classification:

435 91

Abstract:

The present invention provides a method for site-specific cleavage of double stranded DNA at sequences not less than eight base pairs long, comprising methylating he DNA with a sequence-specific methylase capable of recognizing and methylating a first sequence of the DNA, thereby generating a second sequence of the DNA capable of being recognized by a site-specific endonuclease, the first and second sequences having an overlapping part thereof; the length of the combined methylase and endonuclease recognition sites being not less than eight base pairs long, and cleaving the methylated DNA by treatment with the site-specific endonuclease. This method is useful for increasing the selectivity of cutting DNA stands using restriction endonucleases, thereby permitting the isolation of large DNA fragments and the generation of unique sites in DNA fragments, e. g. , cloning vectors. Also provided is a DNA vector having a terminal sequence not less than eight base pairs long which can be recognized and cut by a site-specific endonuclease.