May reduce toxic product malonic semialdehyde to 3-hydroxypropionic acid, which is excreted. RutE is apparently supplemented by YdfG. Required in vivo, but not in vitro in pyrimidine nitrogen degradation. 3-hydroxypropanoate + NADP(+) = 3-oxopropanoate + H(+) + NADPH Up-regulated by the nitrogen regulatory protein C (NtrC also called GlnG) and repressed by RutR. Cells lacking this gene lose the ability to utilize pyrimidine nucleosides and bases as the sole source of nitrogen at room temperature. The Rut pathway degrades exogenous pyrimidines as the sole nitrogen source at room temperature but not at 37 degrees Celsius, a restriction that is apparently a consequence of an inadequate ability to remove toxic malonic semialdehyde at the higher temperature (RutE/YdfG function). Belongs to the nitroreductase family. HadB/RutE subfamily.