Restriction digests of pDdeM1.6 give the following sizes (kb): BamHI--5.2, 1.3; BglII--6.6; ClaI/HindIII--4.4, 1.9; EcoRI--6.6; HindIII--6.4. Restriction digests of pDdeR2.3 give the following sizes (kb): BamHI--4.4, 2.25; BglII--6.6; ClaI/HindIII--5.2, 1.4; EcoRI--6.6; HindIII--5.4, 1.4. The pDdeM1.6 insert contains the following restriction sites (approximate kb from the 5' end): BamHI--0.8; BglII--1.0. The 2.3 kb BamHI fragment contains all of the endonuclease and part of the methylase. Both are transcribed in the same direction. pDdeM1.6 encodes a truncated methylase that lacks 33 amino acids from the carboxy terminus and that are replaced by 6 amino acids from pBR322. This protein shows higher activity and stability than the wild type product. Avoid overgrowth and storage of cultures. |
