Repression of mab_1999 impairs growth and alters cellular morphology of Mycobacterium abscessus.

Background: Cell division is essential for bacterial survival and represents a promising target for the development of novel antibiotics, particularly in mycobacteria. The role of the division protein FtsL in Mycobacterium abscessus remains poorly understood. This study investigated the effects of MAB_1999, a predicted homolog of FtsL, on the growth and cell division of M. abscessus.

Method: To investigate the function of mab_1999, a knockdown mutant was generated via CRISPR interference (CRISPRi). The phenotypic impact of mab_1999 suppression was evaluated, with a focus on its effects on M. abscessus growth, cellular morphology, and antibiotic susceptibility.

Results: The putative homolog of FtsL in M. abscessus (MAB_1999) shares 54% amino acid sequence identity with FtsL from M. smegmatis (MSMEG_4234). CRISPRi-mediated repression of mab_1999 expression resulted in cell elongation and growth defects, although complete growth arrest was not observed. Furthermore, reduced mab_1999 expression increased the susceptibility of M. abscessus to β-lactam antibiotics, including ceftriaxone and imipenem.

Conclusions: Our findings suggest that mab_1999 is involved in cell division and cell wall integrity in M. abscessus. However, further investigation is necessary to confirm its identity as FtsL and to fully elucidate its role in the cell division process and cell wall synthesis.