The attC is a site specific recombination hot spot of different mobile elements.

CECILIA QUIROGA; DANIELA CENTRÓN

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

The sites attC are genetic elements involved in the site-specific recombination of gene cassettes mediated by the tyrosine recombinase integrase, and in the recombination of class C-attC group II (CattG2) introns. Their general structure consists of two short regions of sequence similarity at their boundaries (1R-2R and 1L-2L) separated by a stretch of imperfect internal dyad symmetry. The sites attC form stem-loop structures through a single strand DNA intermediate. The goal of this work was to understand the evolution of three genetic elements: attCs, integrases and CattG2 introns, which converge in two different site-specific recombination mechanisms. Seventy bacterial genomes were selected by their identity to the S.ma.I2 intron, inserted within an attC site of a class 1 integron. Only 11 introns (15.7%) showed an 46% identity to S.ma.I2 and belonged to a genome that also encoded an integrase. Sequence analysis with computational tools showed that all CattG2 introns invade the TTGTT motif and were inserted downstream of or in stem-loops structures. Three out of 5 stems were located within chromosomal integrons, which suggest that they can be identified as typical attC sites. Hence, genome evolution seems to converge in the use of a common target site for two different recombination systems.