Glby, is a PBP with β-lactamase activity and is required for in vivo viability of M. abscessus

The prevalence of Mycobacteroides abscessus, Mab, (also known as Mycobacterium abscessus) has been increasing steadily globally. Patients with structural lung conditions such as bronchiectasis, cystic fibrosis and chronic obstructive pulmonary disease are at high risk of developing pulmonary Mab disease. The disease is often recurrent as the current treatment regimen is considered sub-efficacious. The cell wall peptidoglycan of bacteria is required for their viability and its biosynthetic pathway is enriched in proteins whose inhibition is the basis for two of the most widely used classes of antibiotics to treat bacterial infections. The peptidoglycan of Mab is distinct from that of most bacteria as its synthesis involves penicillin binding proteins (PBP) and L,D-transpeptidases. Here, we demonstrate that Mab gene locus MAB_3167c encodes a PBP (hereafter referred to as Glby) and is required for normal planktonic growth in liquid broth. Glby exhibits a strong {beta}-lactamase activity and is sensitive to {beta}-lactamase inhibitors. In a mouse model of pulmonary Mab disease, mutant lacking this gene was unable to proliferate, gradually cleared and undetectable after three weeks. In a collection of 1.046 Mab clinical isolates, there is evidence that changes in amino acid sequence that compromise Glby function are not favored. These evidences suggest that an agent that can inhibit Glby in vivo has the potential to be an efficacious treatment against Mab disease.