AMINO-ACID FUNCTIONAL-GROUPS INVOLVED IN THE BINDING OF ESCHERICHIA-COLI RIBOSOMAL-PROTEIN S1 TO RIBOSOMES AND NUCLEIC-ACIDS

Histidine, arginine, tyrosine, lysine and cysteine residues of protein S1 were modified with diethyl pyrocarbonate & rose bengal, 2,3-butane dione (diacetyl), tetranitrcmethane, pyridoxal 5-phosphate, and N-ethy l-maleimide, respectively. Modification of the residues and the number of modified residues were determined by either fluorescence or UV spe ctroscopy. The effect of chemical modification on the function of prot ein 31 was studied with respect to nucleic acid (poly U and M13 ssDNA) binding and ribosame binding properties of the protein. We tested S1 binding to these two types of polynucleotides because of their reporte d (Draper et al. (1977) PNAS 74, 4786-4790) binding to two different s ites on Sf. The results indicate that histidine and lysine residues of S1 play an important role in the binding of S1 to both types of nucle ic acids and that histidine and to some extent tyrosine residues are i nvolved in the binding of S1 to ribosomes. The Data indicate the need for a re-evaluation of the two nucleic acid binding-site model