Molecular coevolution of mammalian ribosomal gene terminator sequences and the transcription termination factor TTF-I

摘要: Abstract Both the DNA elements and nuclear factors that direct termination of ribosomal gene transcription exhibit species-specific differences. Even between mammals--e.g., human mouse--the signals are not identical respective (TTFs) which bind to terminator sequence fully interchangeable. To elucidate molecular basis for this species-specificity, we have cloned TTF-I from mouse cells compared their structural functional properties. Recombinant exhibits binding terminates both in cell-free assays transfection experiments. Chimeric constructs reveal major determinant resides within C terminus TTF-I. Replacing 31 C-terminal amino acids with homologous sequences relaxes DNA-binding specificity and, as a consequence, allows chimeric factor specifically stop rDNA transcription.