Reassortment of DNA recognition domains and the evolution of new specificities

Gann, A. A., Campbell, A. J., Collins, J. F., Coulson, A. F., Murray, N. E. (July 1987) Reassortment of DNA recognition domains and the evolution of new specificities. Molecular Microbiology, 1 (1). pp. 13-22. ISSN 0950-382X (Print)0950-382x

DOI: 10.1111/j.1365-2958.1987.tb00521.x


Type I restriction enzymes comprise three subunits only one of which, the S polypeptide, dictates the specificity of the DNA sequence recognized. Recombination between two different hsdS genes, SP and SB, led to the isolation of a system, SQ, which had a different specificity from that of either parent. The finding that the nucleotide sequence recognized by SQ is a hybrid containing components from both the SP and SB target sequences suggested that DNA recognition is carried out by two separable domains within each specificity polypeptide. To test this we have made the recombinant gene of reciprocal structure and demonstrate that it encodes a polypeptide whose recognition sequence, deduced in vivo, is as predicted by this model. We also report the sequence of the SB specificity gene, so that information is now available for the five known members of this family of enzymes. All show a similar organization of conserved and variable regions. Comparisons of the predicted amino acid sequences reveal large non-conserved areas which may not even be structurally similar. This is remarkable since these different S subunits are functionally identical, except for the specificity with respect to the DNA sequence with which they interact. We discuss the correlation of the variation in polypeptide sequence with recognition specificities.

Item Type: Paper
Uncontrolled Keywords: Bacteriophage lambda/*genetics Base Sequence *Biological Evolution DNA Restriction Enzymes/*genetics Escherichia coli/enzymology/*genetics *Genes *Genes, Viral Macromolecular Substances Molecular Sequence Data
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > restriction enzyme
CSHL Authors:
Communities: School of Biological Sciences > SBS Administration
Depositing User: Matt Covey
Date: July 1987
Date Deposited: 23 Jun 2014 18:41
Last Modified: 09 Sep 2021 18:54
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