The S.ma.I2 class C group II intron inserts at integron attC sites

CECILIA QUIROGA; PAUL H. ROY; DANIELA CENTRÓN

MICROBIOLOGY-UK

SOC GENERAL MICROBIOLOGY

Año: 2008 vol. 154 p. 1341 - 1353

1350-0872

We previously found the class C S.ma.I2 group II (GII) intron in Serratia marcescens SCH909inserted into the variable region of a class 1 integron within the attC site of the ant(299)-Ia genecassette. Here, we demonstrate that this ant(299)-Ia : : S.ma.I2 gene cassette is arecombinationally active element despite the presence of the S.ma.I2 intron. In addition, S.ma.I2 isan active GII intron capable of performing self-splicing and invading specific target sites. Intronhoming to a DNA target site is RecA-independent and recognizes the intron binding site (IBS)1and IBS3 regions, formed by the 59 TTGTT 39 consensus sequence located within the inversecore site of attC integrons. Our results also indicate that the process for S.ma.I2 intronmobilization involves a secondary structure provided by the folding of the complete attC site.Moreover, phylogenetic analysis of the class C GII introns showed a clear divergent clade formedby introns that insert within specific sites usually associated with lateral gene transfer.