ATP Sulfurylase is Essential for the Utilization of Sulfamate as a Sulfur Source in the Yeast Komagataella pastoris (syn. Pichia pastoris)

The methylotrophic yeast Komagataella pastoris (syn. Pichia pastoris) is one of the few known yeasts that can utilize sulfamate ([Formula: see text] ) as a sulfur source. The biochemical pathway responsible for the catabolism of sulfamate has yet to be identified. The present study sought to investigate whether sulfamate catabolism proceeds through either of the inorganic sulfur intermediates sulfate ([Formula: see text] ) or sulfite ([Formula: see text] ) before its assimilation and subsequent incorporation into sulfur-containing amino acids and their derivatives. Two key genes in the K. pastoris inorganic sulfur assimilation pathway were deleted separately and the ability of each deletion mutant to utilize sulfamate and other selected sulfur sources was studied. Deletion of the MET3 gene (which encodes the enzyme ATP sulfurylase) did not affect growth on l-methionine, sulfite, methanesulfonate, or taurine but completely abolished growth on sulfate, methyl sulfate and sulfamate. Deletion of the MET5 gene (which encodes the β subunit of the enzyme sulfite reductase) abolished growth on all tested sulfur sources except l-methionine. These results suggest that the catabolism of sulfamate proceeds through a sulfate intermediate before its assimilation.