Novel Type III Polyketide Synthases Biosynthesize Methylated Polyketides in Mycobacterium marinum

Abstract

Mycobacterial pathogenesis is hallmarked by lipidic polyketides that decorate the cell envelope and mediate infection. However, factors mediating persistence remain largely unknown. Dynamic cell wall remodeling could facilitate the different pathogenic phases. Recent studies have implicated type III polyketide synthases (PKSs) in cell wall alterations in several bacteria. Comparative genome analysis revealed several type III pks gene clusters in mycobacteria. In this study, we report the functional characterization of two novel type III PKSs, MMAR_2470 and MMAR_2474, in Mycobacterium marinum. These type III pkss belong to a unique pks genomic cluster conserved exclusively in pathogenic mycobacteria. Cell-free reconstitution assays and high-resolution mass spectrometric analyses revealed methylated polyketide products in independent reactions of both proteins. MMAR_2474 protein exceptionally biosynthesized methylated alkyl-resorcinol and methylated acyl-phloroglucinol products from the same catalytic core. Structure-based homology modeling, product docking, and mutational studies identified residues that could facilitate the distinctive catalysis of these proteins. Functional investigations in heterologous mycobacterial strain implicated MMAR_2474 protein to be vital for mycobacterial survival in stationary biofilms. Our investigations provide new insights into type III PKSs conserved in pathogenic mycobacterial species.

Cytochrome P450 Monooxygenase CYP139 Family Involved in the Synthesis of Secondary Metabolites in 824 Mycobacterial Species

“…In this direction, analysis of some secondary metabolite functions pointed out that some secondary metabolites are certainly helping mycobacterial species to survive in their hosts. For example, MAR/MAP BGC products are found to be part of the cell envelope in M. marinum , possibly complicating its access to host immune system or drug actions [30]; Akaeolide has cytotoxic activity against fibroblasts, suggesting it may play a role in tissue weakening in the host [31]; JBIR-100 exhibits cytotoxic activities and inhibition of proton pumps such as vacuolar-type ATPases (V-ATPases) activities and is thus linked with an increasing number of diseases such as osteopetrosis, male infertility and renal acidosis [32,33]. Lorneic acid A inhibits phosphodiesterase PDE5 blocking the degradation of cGMP [34] and thus it might be playing a role in pulmonary hypertension.…”

Comparative genomics reveals complex natural product biosynthesis capacities and carbon metabolism across host‐associated and free‐living Aquimarina (Bacteroidetes, Flavobacteriaceae) species

“…PKSother clan A, for instance, possessed three GCFs of which one was found exclusively in members of functional group 2 (A. megaterium-macrocephali-atlantica). All BGCs in the clan encode for type III PKSs, well-known for their immense potential to synthesize small compounds with a high structural and bioactivity diversity (Parvez et al, 2018). Interestingly, within PKSother clan B are the BGCs involved with the biosynthesis of a novel polyketide named cuniculene, recently described for Aquimarina sp.…”

Mycobacterium smegmatisexpands across surfaces using hydraulic sliding

“…The top of the protrusion was preserved and appeared to be a comparatively thick (at least 20 cell layers) pellicle that resembled the mycobacterial pellicles generated on the surface of liquid cultures ( Fig. 5; Pang et al, 2012;Parvez et al, 2018). The bacteria were inoculated at a solid-air interface and proceeded to create a liquid-air interface biofilm; a phenomenon apparently not previously observed.…”