A CRISPR-nonhomologous end-joining-based strategy for rapid and efficient gene disruption in Mycobacterium abscessus

Mycobacterium abscessus, a fast-growing, non-tuberculous mycobacterium resistant to most antimicrobial drugs, causes a wide range of serious infections in humans, posing a significant public health challenge. The development of effective genetic manipulation tools for M. abscessus is still in progress, limiting both research and therapeutic advancements. However, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) systems have emerged as promising tools for generating highly specific double-strand breaks (DSBs) in its genome. One of the mechanisms that repair these DSBs is the error-prone nonhomologous end-joining (NHEJ) pathway, which facilitates targeted gene editing. In this study, we introduced a novel application of the CRISPR-NHEJ approach in M. abscessus. We demonstrated that NrgA from M. marinum plays a crucial role in repairing DSBs induced by the CRISPR-Cas system in M. abscessus. Contrary to previous findings, our study also revealed that inhibiting or overexpressing components of homologous recombination/single-strand annealing significantly reduces the efficiency of NHEJ repair in M. abscessus. This discovery challenges current perspectives and suggests that NHEJ repair in M. abscessus may involve components from both homologous recombination and single-strand annealing pathways, highlighting the complex interactions among the three DSB repair mechanisms in M. abscessus.