A RIBOSOMAL-PROTEIN FROM THERMUS-THERMOPHILUS IS HOMOLOGOUS TO A GENERAL SHOCK PROTEIN

The gene encoding the ribosomal protein from Thermus thermophilus, TL5 , which binds to the 5S rRNA, has been cloned and sequenced. The codon usage shows a clear preference for G/C rich codons that is characteri stic for many genes in thermophilic bacteria. The deduced amino acid s equence consists of 206 residues. The sequence of TL5 shows a strong s imilarity to a general shock protein from Bacillus subtilis, named CTC . The protein CTC is homologous in its N-terminal part to the 5S rRNA binding protein, L25, from E coli. An alignment of the TL5, CTC and L2 5 sequences displays a number of residues that are totally conserved. No clear sequence similarity was found between TL5 and other proteins which are known to bind to 5S rRNA. The evolutionary relationship of a heat shock protein in mesophiles and a ribosomal protein in thermophi lic bacteria as well as a possible role of TL5 in the ribosome are dis cussed.