Using Genomic Data to Determine the Diversity and Distribution of Target Site Motifs Recognized by Class C-attC Group II Introns

The attC sites are well-known integrase-targeted elements involved in the insertion and excision of gene cassettes from integrons. Recently, functional analysis of Sma.I2, a class C-attC group II intron, showed that this mobile element invades the attC sites through a specific process. The analysis of genomic data indicates that class C-attC group II introns are independently acquired by their bacterial hosts and evolve in the recognition of a variety of target sites, including the attCs. In addition, adaptation of class C-attC group II introns seemed to be favourable for particular genera, such as Shewanella, suggesting a possible niche for the spread of class C-attC group II introns inserted at attC sites. This understanding suggests a functional role of short palindromic DNA sequences, such as the attCs, as important tools for the acquisition of mobile elements associated with horizontal gene transfer. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.