Characterization of a novel cold-adapted phosphinothricin N-acetyltransferase from the marine bacterium Rhodococcus sp. strain YM12

Phosphinothricin (PPT) is a kind of non-selective, environmentally friendly herbicide. PPT-tolerance genes are vital in both plant biotechnology as selectable markers and the development of transgenic herbicide-resistant crops. However, there are no other well-identified and commercially available PPT-resistance genes for use in plant genetic engineering besides two PPT N-acetyltransferase genes, which known as pat and bar derived from Streptomyces sp. Here, we isolated a novel PPT N-acetyltransferase gene from PPT-resistant marine bacteria, Rhodococcus sp. strain YM12. The gene, designated as RePAT, encoded a protein (RePAT) of 162 amino acids, which showed 37% identity with that of PAT proteins. Key kinetic constants of RePAT were determined (Km = 0.076 mM, Kcat = 131 min−1) using PPT as a substrate, the enzyme retained considerable activity at pH 8.0 and had an optimum temperature of 35 °C. Interestingly, it possessed over 50% of its maximal activity at temperature conditions between 0 and 10 °C, suggesting that this enzyme is able to protect crop against PPT injury in cold environment. These results illustrated that RePAT could be a new resource for herbicide detoxification by transgenic crops.