Detection of enzymatic activities related to the tRNA splicing pathway in Methanosarcina acetivorans cell extract.

At least two separate enzymes, an endonuclease and a ligase, are thought to be involved in the tRNA splicing pathway. The yeast and archaeal endonucleases acting in the first step of tRNA splicing commonly produce 2', 3'-cyclic phosphate and 5' hydroxy group at the exon-intron borders. Despite this similarity in the first step of tRNA splicing, the subsequent mechanism of archaeal splicing pathway has not been elucidated yet. We have been searching for the archaeal ligase activity from Methanosarcina acetivorans. Here, we report the distinct activity of a splicing endonuclease detected in its cell extract.