The S.ma.I2 class C group II intron inserts at integron attC sites.
We previously found the class C S.ma.I2 group II (GII) intron in Serratia marcescens SCH909 inserted into the variable region of a class 1 integron within the attC site of the ant(2'')-Ia gene cassette. Here, we demonstrate that this ant(2'')-Ia : : S.ma.I2 gene cassette is a recombinationally active element despite the presence of the S.ma.I2 intron. In addition, S.ma.I2 is an active GII intron capable of performing self-splicing and invading specific target sites. Intron homing to a DNA target site is RecA-independent and recognizes the intron binding site (IBS)1 and IBS3 regions, formed by the 5' TTGTT 3' consensus sequence located within the inverse core site of attC integrons. Our results also indicate that the process for S.ma.I2 intron mobilization 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 formed by introns that insert within specific sites usually associated with lateral gene transfer.
Quiroga
Cecilia
C
Centre de Recherche en Infectiologie, Université Laval, Québec, Canada.|Departamento de Microbiología, Inmunología y Parasitología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
Roy
Paul H
PH
Département de Biochimie et de Microbiologie, Université Laval, Québec, Canada.|Centre de Recherche en Infectiologie, Université Laval, Québec, Canada.
Centrón
Daniela
D
Departamento de Microbiología, Inmunología y Parasitología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial / Q000235:genetics*; D032023:Integrons; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012326:RNA Splicing; D012329:RNA, Bacterial / Q000235:genetics*; D011938:Rec A Recombinases / Q000235:genetics; D011995:Recombination, Genetic; D012689:Sequence Homology, Nucleic Acid; D012706:Serratia marcescens / Q000235:genetics*
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D011938:Rec A Recombinases