Archaeal proline dehydrogenase from Pyrobaculum aerophilum : sequence comparison.

Abstract

Based on the amino acid sequence, proline dehydrogenase from hyperthermophilic archaeon, Pyrobaculum aerophilum showed no significant homology with previously known bacterial proline dehydrogenase, as exemplified with Salmonella typhimurium and Escherichia Coli putA proteins, as well as archaeal dye-linked L-proline dehydrogenase from Thermococcus profundus. Multiple sequence alignment revealed a close relation to the archaeal FAD dependent oxidoreductase enzyme family. Gene organizations around Pyrobaculum aerophilum proline dehydrogenase and archaeal FAD dependent oxidoreductases were similar, suggesting possibly similar amino acid regulation and catabolism. However, differences were recorded in the stereospecificity of amino acid activity. The predicted model of Pyrobaculum aerophilum proline dehydrogenase demonstrated high structural similarity to sarcosine oxidase from Corynebacterium sp. U-96 and L-proline dehydrogenase from Pyrococcus horikoshii with root mean square deviation of 2.043 and 1.983 respectively. Nonetheless, low amino acid sequence homology categorizes the Pyrobaculum aerophilum enzyme as an independent class of enzymes.