The physical localization of the gene for ribosomal protein S20.

As a prerequisite to the examination of the structure and properties of the promoter for ribosomal protein S20 of Escherichia coli, I have determined the cleavage sites in lambdadapB2cI857S7 DNA for four restriction endonucleases. Subsequently, purified fragments obtained after digestion of this DNA with BamI or HindIII have served as templates for coupled transcription and translation. This has permitted the localization of the structural gene for S20 within a 1000 base pair segment of lambdadapB2cIB57S7 DNA . Cleavage of this DNA with HindIII partially inactivates the expression of S20 in vitro, implying that one HindIII site lies in or near a region essential for the expression of S20.