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Effect of peptidoglycan amidase MSMEG_6281 on fatty acid metabolism in Mycobacterium smegmatis

Miao, Jiatong, Liu, Hanrui, Qu, Yushan, Fu, Weizhe, Qi, Kangwei, Zang, Shizhu, He, Jiajia, Zhao, Shijia, Chen, Shixing, Jiang, Tao
Microbial pathogenesis 2020 v.140 pp. 103939
ABC transporters, Mycobacterium smegmatis, acyl coenzyme A, acyl-CoA dehydrogenase, amidase, biofilm, cell walls, fatty acid metabolism, gene targeting, liquid chromatography, mycolic acids, pathogenicity, peptides, peptidoglycans, phenotype, protein-protein interactions, proteome, proteomics, tandem mass spectrometry
Mycobacterium smegmatis MSMEG_6281, a peptidoglycan (PG) amidase, is essential in maintaining cell wall integrity. To address the potential roles during the MSMEG_6281-mediated biological process, we compared proteomes from wild-type M.smegmatis and MSMEG_6281 gene knockout strain (ΔM_6281) using LC-MS/MS analysis. Peptide analysis revealed that 851 proteins were differentially produced with at least 1.2-fold changes, including some proteins involved in fatty acid metabolism such as acyl-CoA synthase, acyl-CoA dehydrogenase, MCE-family proteins, ATP-binding cassette (ABC) transporters, and MmpL4. Some proteins related to fatty acid degradation were enriched through protein-protein interaction analysis. Therefore, proteomic data showed that a lack of MSMEG_6281 affected fatty acid metabolism. Mycobacteria can produce diverse lipid molecules ranging from single fatty acids to highly complex mycolic acids, and mycobacterial surface-exposed lipids may impact biofilm formation. In this study, we also assessed the effects of MSMEG_6281 on biofilm phenotype using semi-quantitative and morphology analysis methods. These results found thatΔM_6281 exhibited a delayed biofilm phenotype compared to that of the wild-type M.smegmatis, and the changes were recovered when PG amidase was rescued in a ΔM_6281::Rv3717 strain. Our results demonstrated that MSMEG_6281 impacts fatty acid metabolism and further interferes with biofilm formation. These results provide a clue to study the effects of PG amidase on mycobacterial pathogenicity.