coli in rich or minimal media. Queuosine is widely distributed in bacteria, and it is present in Erlotinib EGFR inhibitor the first base of the anticodon of tRNAAsp, tRNAAsn, tRNAHis and tRNATyr . however in E. coli only tRNAAsp is a substrate for the GluQ RS enzyme. The presence of modifications within the anticodon loop of the tRNA, could enhance the accuracy of the codon binding. Then the tRNAAspQ34 might improve recognition of both GAC and GAU codons and stimulate the binding of the GAU codon to the ribo some. In Shigella flexneri it has been shown that mutations in genes required for tRNA modifications, miaA and tgt decreased virulence. miaA is required for 2 methylthio N6 isopentenyladenosine modification at position 37 of the anticodon loop and tgt is involved in queuosine modification at position 34 within the anti codon loop.

In this study, we determined the role of the genome organization and its effect on the expression of the gluQ rs gene in the major human pathogen, S. flexneri. Results Genomic organization of the S. flexneri gluQ rs gene GluQ RS is required for the synthesis of the modified nucleoside, GluQ, present on tRNAAsp. By searching the bacterial protein database Uniprot we were able to identify Inhibitors,Modulators,Libraries GluQ RS in more than a hundred bacterial species, primarily proteo bacteria. From the phylogenetic analysis we can distinguished the three subgroups of enzymes described by Dubois et al, 2004, which are characterized by the presence of the signature HXGS, Inhibitors,Modulators,Libraries HXGN or HXGH in the adenylate binding site. A similar tree was obtained using the Neighbor joining method.

Phylogenetic analysis within the subgroup of enzymes with the HXGN motif, included representatives from the Firmicutes bacterial group together with Desulfovibrio vulgaris and Truepera radio victrix enzymes. From the Inhibitors,Modulators,Libraries alignment, these members have 8 characteristic amino Inhibitors,Modulators,Libraries acids, G70PDXGGXX, that do not align with the other GluQ RS. Further genomic ana lysis indicated that the gluQ rs gene is found primarily in two genomic arrangements, either alone or located imme diately downstream of dksA. Searching within the String database and GenomeNet, we found that the dksA gluQ rs gene organization was conserved in more than 40 different species, all of which were within the gammaproteobacteria group. These included species of Aeromonadales, Alteromonadales, Enterobacteriaceae, in cluding E. coli and S.

flexneri, Pseudomanadales, Inhibitors,Modulators,Libraries and Vibrionaceae. A bioinformatics analysis of the intergenic region between dksA and gluQ rs showed great variation in the distance between the two genes among these bacterial species. In S. flexneri the intergenic region between the stop codon of dksA and the first codon of gluQ rs is only 39 base pairs. Therefore, we suspected that the tran selleck chem scription of gluQ rs was regulated by the previously characterized dksA promoter. To test this hypoth esis, we isolated total mRNA and performed RT PCR to identify an mRNA that included both genes.