Two thymidylate synthetases in Bacillus subtilis.

Abstract

Bacillus subtilis grown at temperatures below 37 degrees contains two thymidylate synthetases, TSaseA and TSaseB. Their presence is dependent on functional thyA and thyB genes, respectively. When cells are grown at 46 degrees they only contain TSaseA activity. This allous an easy positive selection for thyA and thyA, THYB mutants. The two TSases have been physically separated, and they show similar overall requirements for activity. However, they differ significantly in both their kinetic and their physicochemical properties.