This PRTase family, and C-terminal TRSP domain, are related to OPRTases [1], and are predicted to use Orotate as substrate. These genes are found in the biosynthetic operon associated with the Ter stress-response operon and are predicted to be involved in the biosynthesis of a ribo-nucleoside involved in stress response [1].

1: Ter-dependent stress response systems: novel pathways related to metal sensing, production of a nucleoside-like metabolite, and DNA-processing. Anantharaman V, Iyer LM, Aravind L; Mol Biosyst. 2012;8:3142-3165. PMID:23044854