RT Journal Article SR Electronic(1) A1 Pandey, Satya Deo A1 Jain, Diamond A1 Kumar, Neeraj A1 Adhikary, Anwesha A1 Kumar N., Ganesh A1 Ghosh, Anindya S.YR 2020 T1 MSMEG_2432 of Mycobacterium smegmatis mc2155 is a dual function enzyme that exhibits DD-carboxypeptidase and β-lactamase activities JF Microbiology, VO 166 IS 6 SP 546 OP 553 DO https://doi.org/10.1099/mic.0.000902 PB Microbiology Society, SN 1465-2080, AB Mycobacterial peptidoglycan (PG) is an unsolved puzzle due to its complex structure and involvement of multiple enzymes in the process of its remodelling. dd-Carboxypeptidases are low molecular mass penicillin-binding proteins (LMM-PBPs) that catalyzes the cleavage of terminal d-Ala of muramyl pentapeptide branches and thereby helps in the PG remodelling process. Here, we have assigned the function of a putative LMM-PBP, MSMEG_2432 of Mycobacterium smegmatis , by showing that it exhibits both dd-CPase and β-lactamase activities. Like conventional dd-CPase (PBP5 from E. coli), upon ectopic complementation in a deformed seven PBP deletion mutant of E. coli, MSMEG_2432 has manifested its ability to restore ~75 % of the cell population to their normal rod shape. Further, in vitro dd-CPase assay has confirmed its ability to release terminal d-Ala from the synthetic tripeptide and the peptidoglycan mimetic pentapeptide substrates ending with d-Ala-d-Ala. Also, elevated resistance against penicillins and cephalosporins upon ectopic expression of MSMEG_2432 suggests the presence of β-lactamase activity, which is further confirmed in vitro through nitrocefin hydrolysis assay. Moreover, it is found apparent that D169A substitution in MSMEG_2432 influences both of its in vivo and in vitro dd-CPase and β-lactamase activities. Thus, we infer that MSMEG_2432 is a dual function enzyme that possesses both dd-CPase and β-lactamase activities., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000902