[RNA-recognizing function of the DNA-recognizing structure helix-turn-helix in ribosomal proteins S4 and S7 of Escherichia coli and plant chloroplasts].

The segments which satisfy the necessary requirements for DNA-recognizing structure helix-turn-helix coding have been found in amino acid sequences of RNA-recognizing E. coli ribosomal proteins S4 and S7. It has appeared that among these segments there are those that in chloroplasts S4 and S7 homologues satisfy these necessary requirements also: S4-97-121 and 108-132 (Ec), 91-115 and 102-126 (Zea mays); S7-109-133 (Ec) 110-134 (Euglena gracilis, Glycine max). Such segments have been confronted with known experimental data on 16S rRNA-binding region localization. It has appeared: 1) the segment 97-121 of S4 is localized in RNA-recognizing fragment 46-124 and one of two RNA-binding regions of this fragment containing Lys-120--belongs to the predicted DNA-recognizing structure; the segment 109-133 of S7 includes the only RNA-binding region of S7-113-117. It is concluded that E. coli ribosomal proteins S4 and S7 and their homologues from plant chloroplasts have a DNA-recognizing structure helix-turn-helix performing the RNA-recognizing function.