N-terminal domain, residues 1-91, of ribosomal protein TL5 from Thermus thermophilus binds specifically and strongly to the region of 5S rRNA containing loop E

In this work we show for the first time that the overproduced N-terminal fr agment (residues 1-91) of ribosomal protein TL5 binds specifically to 5S rR NA and that the region of this fragment containing residues 80-91 is a nece ssity for its RNA-binding activity. The fragment of Escherichia coli 5S rRN A protected by TL5 against RNase A hydrolysis was isolated and sequenced. T his 39 nucleotides fragment contains loop E and helices IV and V of 5S rRNA , The isolated RNA fragment forms stable complexes with TL5 and its N-termi nal domain. Crystals of TL5 in complex with the RNA fragment diffracting to 2.75 Angstrom resolution were obtained. (C) 1999 Federation of European Bi ochemical Societies.