Metal ion catalysis during group II intron self-splicing: parallels with the spliceosome

Article Abstract:

Metal ion catalysis takes place in group II intron self-splicing and striking parallels with the spliceosome exist. The 3'-sulfur substitution at the 5' splice site of a group II intron causes a metal specificity switch in the first step of splicing. Comparisons of mechanism for group II self-splicing introns and the spliceosome are important in finding out whether the two means of splicing are related. The 3'-sulfur substitution of a spliceosomal intron has just the same effects found in cis-splicing of the group II intron.

Physiological aspects, Metal ions

Functional interactions of Prp8 with both splice sites at the spliceosomal catalytic center

Article Abstract:

Functional interactions of Prp8 having two splice sites at the spliceosomal catalytic center are discussed. Prp8 is remarkably conserved in a wide range of organisms, seems to be central to the spliceosome, and interacts directly with the GU dinucleotide at the 5'SS, so the exact location of the 5'SS:h-Prp8 UV cross link has been mapped and striking proximity showed up for two of the prp8 (ital) suppressor mutations with the site of the 5'SS:hPrp8 crosslink. .

Physiological regulation, Biological control systems, Messenger RNA

Initial recognition of U12-dependent introns requires both U11/5' splice-site and U12/branchpoint interactions

Article Abstract:

Studies using RNase H protection assays support the theory that intron recognition exhibits greater rigidity than the major spliceosome processes. Recognition of branchpoint sequence and 5' splice-site elements by U12 and U11 snRNPs displays significant cooperativity, and both sites are required within the pre-mRNA substrate to generate efficient complex formation.

Nucleotide sequence, Base sequence