Presence of class C group II introns among Shewanella isolates.

CECILIA QUIROGA; DANIELA CENTRÓN

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008

Bacterial group II introns are organized in several classes, from A to F, and distributed in several microorganisms. These elements have the ability to move to new regions in a genome through an RNA intermediate by a retrohoming event. Previously, we found that a class C group II intron from Shewanella baltica OS185 shared a common ancestor with the S.ma.I2 intron from the clinical isolate Serratia marcescens. The aim of this work was to identify the class C group II introns among Shewanella isolates and to determine their genetic contexts. We searched for S.ma.I2 homologues in 10 Shewanella clinical and 7 environmental isolates using the PCR technique with specific primers. All the isolates harboured a group II intron; while the Shewanella algae Sh10 isolate had 100% nucleotide identity with S.ma.I2. In silico analysis showed that over 17 complete and 7 partial genome projects 5 harboured a class C intron in their chromosomes. Alike S.ma.I2, these introns were located downstream of secondary structures indicating a similar mechanism of recombination. Also, a second class of introns, the cloroplast-like class, was also present in Shewanella coexisting with the class C introns. The Shewanella bacteria harbour different intron classes and are potentially involved in the horizontal transference of class C introns to clinical niches.