The DNA Sequence and Structural Characteristic of The 5'-Nontranscribed Spacer of Silkworm Attacus ricini rDNA.

We have found that the SacII-EcoRI fragment in the nontranscribed spacer (NTS) of silkworm Attacus ricini rDNA is a nuclear scaffold-associated region (SRA) and showed the function as the ARS element in yeast. This paper reports the sequence of this NTS region and the various characteristic potential functional motifs as analyzed by computer. It is 1 025 bp long and AT-Rich. With 9 bent DNA motifs, 10 T-boxes, 5 A-boxes motifs, 13 topoisomerase II as well as 15 ARS consensus sequences. In addition, there are several dozens of inverted repeats and ATTA/TAAT, ATTTA/TAAAT, ATATTT/AAATAT motifs commonly believed to be the binding sites of many homeodomain proteins. These motifs, concentrated in the SAR region, may play very important role in the regulation of gene transcription and replication at the chromatin level.