Modification of E. coli ribosomes and coliphage MS2 RNA by bisulfite: effects on ribosomal binding and protein synthesis.

The reaction of E. coli 70s ribosomes with 0.2 M NaH-35 s03 (pH 7.1, 3.5hrs, 37 degree) led to the conversion of 4.5% of the uracil residues of the R, RNA into 5.6-dihydrouracil-6-sulfonate residues. The modified ribosomes exhibited a significant decrease in their ability to bind (14-C)-phenylalanyl-(RNA-phe and to incorporate (14-C)-phenylalanine into protein in the presence of polyuridylic acid. The ability of the modified ribosomes to form an initiation complex as measured by the A-U-G or coliphage MS2 RNA dependent binding of (14-C)-fmet-tRNA-fmet was also impaired, as was their ability to incorporate (14-C) lysine into protein with MS2 RNA as messenger. Treatment os MS RNA with 0.2 M sodium (35-S) bisulfite, pH 7.0 at 25 degrees C resulted in the substitution of 2.7% and 6.2% of the uracil residues by bisulfite after 1 and 3.5 hrs of reaction, respectively. Impairment of function of the MS2 RNA in both initiation complex formation and transplantation assays was observed. These reactions of uracil residues of mRNA and rRNA may be a cause of biological damage inflicted by sodium bisulfite and sulfur dioxide.