Protein Synthesis in Cell-Free Extracts from a Thermoacidophilic Archaebacterium

Abstract

An in vitro polypeptide synthesizing system was developed from the thermoacidophilic archaebacterium, Sulfolobus solfataricus. The stimulation of phenylalanine incorporation by poly U was entirely dependent upon the addition of polyamines or increasing the Mg++ concentration. The largest stimulation was observed at 3 mM spermine in the presence of 10 mM Mg++. The optimal temperature for poly U-directed phenylalaline incorporation was 75 °C. The ability of poly G to code for glycine could be demonstrated in assays incubated at elevated temperatures. When tested at 45 °C, streptomycin and neomycin did not inhibit the poly U-phenylalanine reaction except in the case of neomycin at the highest concentration tested. Neither aminoglycoside induced significant miscoding for leucine at any concentration tested. Chloramphenicol inhibited poly UG-directed phenylalanine incorporation to a small extent. Tetracycline, virginiamycin and cycloheximide were ineffective in inhibiting polyphenylalanine synthesis, but this reaction was slightly inhibited by anisomycin at the highest concentration tested