Regulates the expression of genes involved in peptidoglycan (PG) degradation. Could play a role in switch control between recycling and degradation of PG peptides. Negatively regulates the expression of the ycjY-ymjD-ymjC-mpaA operon by binding to the PgrR-box. In addition, other genes are predicted to be under the control of PgrR, including genes related to membrane formation and function. Belongs to the LysR transcriptional regulatory family.