It claimed 1.5 million lives in 2020, second only to COVID-19 amongst infectious diseases. The organic substrate for BacA-SbmA is unknown, but increased resistance of deficient mutants against peptide antibiotics strongly means that BacA is required for uptake of antimicrobial peptides . Coli sbmA-null mutants are resistant to the proline-rich antimicrobial peptide Bac7, a cathelicidin-derived...