The Glycine and Proline Reduction systems are two of the best characterized selenoenzymes in bacteria and have been found to occur in a wide variety of clostridia [1-5]. These enzymes are utilized to reduce glycine or D-proline to obtain energy via substrate level phosporylation or membrane gradients, respectively [6, 7]. This includes the pathogens C. difficile and C. botulinum [5, 8]. Strains of C. difficile are activate toxigenic pathways whenever either of these pathways is active within the cell [5, 8]. Though evolutionary studies have been conducted on ammonia producing bacteria [9] none has been done to directly characterize these two system by themselves. This includes an understanding of whether or not this system is transferred between organisms, as many of the clostridia that are to be studied are known to have an “open genome.” [8, 10] With this information we were able to generate a phylogenic model of the proline and glycine reduction systems. Through this analysis, we were able to account for many clostridial organisms that contain the system, but also many other organisms as well. These included enterobacteriaceae including a strain of the model organism, Escherichia coli. It was further concluded that Glycine Reductase was a much less centralized system and included a wide range of taxa while Proline Reductase was much more centralized to being within the phyla of firmicutes. It was also concluded that the strain of E. coli has a fully functional operon for Glycine Reductase.

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