Origin of a Core Bacterial Gene via Co-option and Detoxification of a Phage Lysin

？ The morphogenesis gene spmX is constrained to a large bacterial order ？ The muramidase domain of spmX was co-opted from phage ？ Its catalytic cleft has been remodeled but retains attenuated activity ？ The domain now localizes a protein scaffold with roles in cellular morpholog