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Group II introns are both catalytic RNAs and mobile retroelements that move through a process catalyzed by a RNP complex consisting of an intron-encoded protein and the spliced intron lariat RNA. Group II intron-encoded proteins are multifunctional and contain an N-terminal reverse transcriptase domain, followed by a putative RNA-binding domain (domain X) associated with RNA splicing or maturase activity and a C-terminal DNA binding⁄DNA endonuclease region. | ễFEBS Journal Structural features in the C-terminal region of the Sinorhizobium meliloti Rmlntl group II intron-encoded protein contribute to its maturase and intron DNA-insertion function Maria D. Molina-Sanchez Francisco Martinez-Abarca and Nicolas Toro Grupo de Ecología Genetica Estacion ExperimentaldelZaidin Consejo Superior de Investigaciones Cientificas Granada Spain Keywords catalytic RNAs maturase retroelements reverse transcriptase splicing Correspondence N. Toro Estacion ExperimentaldelZaidin Consejo Superior de Investigaciones Cientificas Calle Profesor Albareda 1 18008 Granada Spain Fax 34 9581 29600 Tel 34 9581 81600 E-mail nicolas.toro@eez.csic.es Received 28 September 2009 revised 29 October 2009 accepted 4 November 2009 doi 10.1111 j.1742-4658.2009.07478.x Group II introns are both catalytic RNAs and mobile retroelements that move through a process catalyzed by a RNP complex consisting of an intron-encoded protein and the spliced intron lariat RNA. Group II intron-encoded proteins are multifunctional and contain an N-terminal reverse transcriptase domain followed by a putative RNA-binding domain domain X associated with RNA splicing or maturase activity and a C-terminal DNA binding DNA endonuclease region. The intron-encoded protein encoded by the mobile group II intron RmInt1 which lacks the DNA binding DNA endonuclease region has only a short C-terminal extension C-tail after a typical domain X apparently unrelated to the C-terminal regions of other group II intron-encoded proteins. Multiple sequence alignments identified features of the C-terminal portion of the RmInt1 intron-encoded protein that are conserved throughout evolution in the bacterial ORF class D suggesting a group-specific functionally important protein region. The functional importance of these features was demonstrated by analyses of deletions and mutations affecting conserved amino acid residues. We found that the C-tail of the RmInt1 intron-encoded protein contributes to the .
