Evolution of New Enzymes and Pathways: Soil Microbes Adapt to s-Triazine Herbicides

摘要

Pseudomonas sp. ADP was used as a model to investigate how bacteria evolve new enzymes in new combinations to metabolize s-triazine herbicides. The metabolic pathway provides inorganic nitrogen to support microbial growth. The enzymes that initiate the metabolism of the herbicide atrazine are denoted AtzA, AtzB and AtzC. The enzymes are members of the amidohydrolase superfamily and hydrolytically remove substituents from the s-triazine ring to generate cyanuric acid. Subsequent to that, cyanuric acid is hydrolyzed by a series of amidases to liberate ring carbon and nitrogen as carbon dioxide and ammonia, respectively. The complete suite of atrazine (atz) genes are found on a broad host range plasmid in Pseudomonas sp. ADP. The atz genes have spread globally and are widespread in different genera of bacteria. These studies begin to reveal how bacterial genes involved in the metabolism of anthropogenic chemicals may arise and spread in the environment.