Redesign of RNase T1 aimed to create its ability to bind barstar.

Barnase and RNase T1 are two members from a large family of homologous microbial ribonucleases. Barnase activity is potently inhibited upon binding of the specific protein inhibitor barstar. The crystal structure of the barnase-barstar complex has been solved to a high resolution and forms a structural basis for the analysis of the tight one-to-one non- covalent complex. RNase T1 does not bind with barstar. The aim of this project is to make RNase T1 capable to bind Barstar by protein engineering. The mutants Tyr45Arg%2C Ser37Lys and Ser72Arg wil be constructed by site directed mutagenesis. We estimate that the inhibition constant of the triple mutant will be about 10-9 to 10-10 M