The bacterial Smtr GII intron recognizes the antibiotic resistnace gene cassette attachment site attC.

CECILIA QUIROGA; PAUL H. ROY; DANIELA CENTRÓN

Pinamar, Buenos Aires, Argentina

Congreso; XLI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB).; 2005

elements from the genome formed by a structural gene and a palindromic region called attC site. A group II intron is inserted in an integron gene cassette at the junction of the structural gene and its attC site. Analysis of the S. marcescens GII intron (Smtr) has shown that this intron is capable of invading different antibiotic gene cassettes. Methods. Double transformation of an intron-containing plasmid and 9 different target site-containing plasmids were inserted into E.coli JM109 (RecA-) and JM107 (RecA+). Positive events of the intron insertion was tested by PCR. Phylogenic analysis was done with the ClustalW (V1.86) software and secondary structures were analyzed with the mFOLD (V3.1) software. Results. Positive results have shown insertion at the consensus region TA/ACAA, while the negative targets presented a modification at the ACAA region. The phylogeny analysis of bacterial GII introns reverse transcriptases revealed an cluster for the Smtr-like introns that correlates with the DNA region where they home. Secondary structure analysis shows a stem loop for the attC sites different from other target sites. Conclusion. The Smtr GII intron can be inserted in any antibiotic resistant gene cassettes that has the TA/ACAA target site corresponding to the junction point between the structural gene and its attC, which provides the secondary structure for the target recognition. Smtr-like introns present a different lineage of evolution from other bacteria introns.