Apart from that, the model suggests that only minor changes might be necessary in order to convert the binding pocket of bacterial Tgt such that it exhibits the specificity of the eucaryotic enzyme. Hence, in an attempt to generate a model system for the active site of human Tgt and to gain insights into the relevance of particular amino acids for substrate base selectivity, we adapted the Z. mobilis Tgt active site by site-directed mutagenesis in order to mimic that of the human enzyme. This paper describes the extensive analysis of mutated Z. mobilis Tgt variants created with this objective. Evofosfamide bacteria possess several mechanisms enabling them to respond to changing and unfavorable environmental conditions or to outcompete other bacteria. One particular mechanism is the production and the release of toxins such as bacteriocins. Colicins are the best characterized group of bacteriocins produced by Escherichia coli and active against closely related E. coli bacteria or other members of the Enterobacteriaceae. Experimental studies focus on the mechanism of colicin release, colicin uptake by strains sensitive to the bacteriocin, or the evolutional and ecological importance of colicins. In contrast, the majority of the theoretical investigations have been studying the interplay of colicin-producing bacteria with bacteria that are sensitive to or resistant against the bacteriocin. Toxins, such as the bacteriocin Colicin E2 of this study, are plasmid encoded and expressed from (+)-JQ1 operons under the control of an SOS promoter. The Colicin E2 operon comprises three genes: cea, cei and cel. This operon is only expressed upon induction of the SOS response by e.g. DNA damage. When the Colicin E2 operon is expressed, two different mRNA transcripts can be found. The shorter transcript, which is transcribed at relatively high levels, includes the cea and cei gene. The longer transcript comprising all three genes, is rarely expressed only when the transcriptional terminator T1 can be overcome. For colicin E7 it was shown that translation of the cel gene is further regulated post-transcriptionally by the mRNA binding protein CsrA. CsrA itself is further regulated by the sRNAs CsrB and CsrC. These sRNA bind the CsrA protein and can thereby reduce the amount of free CsrA if sRNA expression is high. Since the operons of Colicin E2 and E7 show a high sequence homology and all regulatory elements present in the colicin E7 operon are also present in the Colicin E2 operon, it is assumed that CsrA is also inhibiting the translation of the lysis gene of the Colicin E2 operon. The co-expression of the colicin gene cea and the immunity gene cei is necessary, since the immunity protein ensures inactivity of the colicin as long as the colicin-immunity protein complex is present within the cell.