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 fragment (residues 1–91) of ribosomal protein TL5 binds specifically to 5S rRNA and that the region of this fragment containing residues 80–91 is a necessity for its RNA-binding activity. The fragment of Escherichia coli 5S rRNA protected by TL5 against RNase A hydrolysis was isolated and sequenced. This 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-terminal domain. Crystals of TL5 in complex with the RNA fragment diffracting to 2.75 Å resolution were obtained.