期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1995
卷号：92
期号：10
页码：4422-4426
DOI：10.1073/pnas.92.10.4422
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Domain 5 (D5) is a small hairpin structure within group II introns. A bimolecular assay system depends on binding by D5 to an intron substrate for self-splicing activity. In this study, mutations in D5 identify two among six nearly invariant nucleotides as being critical for 5' splice junction hydrolysis but unimportant for binding. A mutation at another site in D5 blocks binding. Thus, mutations can distinguish two D5 functions: substrate binding and catalysis. The secondary structure of D5 may resemble helix I formed by the U2 and U6 small nuclear RNAs in the eukaryotic spliceosome. Our results support a revision of the previously proposed correspondence between D5 and helix I on the basis of the critical trinucleotide 5'-AGC-3' present in both. We suggest that this trinucleotide plays a similar role in promoting the chemical reactions for both splicing systems.
