Structural basis of terephthalate recognition by solute binding protein TphC

From Springer Nature via Jisc Publications RouterHistory: received 2021-03-24, accepted 2021-10-06, registration 2021-10-12, pub-electronic 2021-10-29, online 2021-10-29, collection 2021-12Publication status: PublishedFunder: Commonwealth Scholarship Commission (CSC); doi: https://doi.org/10.13039/501100000867; Grant(s): INCN-2018-57Funder: RCUK | Engineering and Physical Sciences Research Council (EPSRC); doi: https://doi.org/10.13039/501100000266; Grant(s): EP/M013219/1, EP/023755/1Funder: RCUK | Biotechnology and Biological Sciences Research Council (BBSRC); doi: https://doi.org/10.13039/501100000268; Grant(s): BB/M011208/1, BB/M011208/1, BB/P01738X/1Abstract: Biological degradation of Polyethylene terephthalate (PET) plastic and assimilation of the corresponding monomers ethylene glycol and terephthalate (TPA) into central metabolism offers an attractive route for bio-based molecular recycling and bioremediation applications. A key step is the cellular uptake of the non-permeable TPA into bacterial cells which has been shown to be dependent upon the presence of the key tphC gene. However, little is known from a biochemical and structural perspective about the encoded solute binding protein, TphC. Here, we report the biochemical and structural characterisation of TphC in both open and TPA-bound closed conformations. This analysis demonstrates the narrow ligand specificity of TphC towards aromatic para-substituted dicarboxylates, such as TPA and closely related analogues. Further phylogenetic and genomic context analysis of the tph genes reveals homologous operons as a genetic resource for future biotechnological and metabolic engineering efforts towards circular plastic bio-economy solutions

Lipopeptide mediated biocontrol activity of endophytic Bacillus subtilis against fungal phytopathogens

Abstract Background The use of chemical fungicides against fungal pathogens adversely affects soil and plant health thereby resulting in overall environmental hazards. Therefore, biological source for obtaining antifungal agents is considered as an environment-friendly alternative for controlling fungal pathogens. Results In this study, seven endophytic bacteria were isolated from sugarcane leaves and screened for its antifungal activity against 10 fungal isolates belonging to the genera Alternaria, Cochliobolus, Curvularia, Fusarium, Neodeightonia, Phomopsis and Saccharicola isolated from diseased leaves of sugarcane. Among the seven bacterial isolates, SCB-1 showed potent antagonistic activity against the tested fungi. Based on the phenotypic data, Fatty Acid Methyl Esters (FAME) and 16S rRNA gene sequence analysis, the isolate SCB-1 was identified as Bacillus subtilis. The bacterial isolate was screened negative for chitinase production; however, chloroform and methanol extracts of the bacterial culture caused significant inhibition in the growth of the fungal isolates on semisolid media. Volatile component assay showed highest inhibitory activity against Saccharicola bicolor (SC1.4). A PCR based study detected the presence of the genes involved in biosynthesis of surfactin, bacillaene, difficidin, macrolactins and fengycin. Mass spectrometric analysis of the bacterial extract detected the presence of antifungal lipopeptide surfactin, but other metabolites were not detected. The biocontrol activity of the bacterial isolate was established when bacterial pretreated mung bean seeds were able to resist Fusarium infection, however, the untreated seeds failed to germinate. Conclusion The antifungal potential of isolate Bacillus subtilis SCB-1 was established against taxonomically diverse fungal pathogens including the genera Saccharicola, Cochliobolus, Alternaria and Fusarium. The potent antifungal compound surfactin as well as volatiles produced by the bacterial isolate could be responsible for its bio-control activity against fungal infections

Fungal interactions induce changes in hyphal morphology and enzyme production

In nature, species interacts/competes with one other within their surrounding for food and space and the type of interactions are unique to each species. The interacting partners secrete different metabolites, which may have high importance in human welfare. Fungal–fungal interactions are complex mechanisms that need better understanding. Here, 14 fungal isolates were facilitated in 105 possible combinations to interact on potato dextrose agar. Morphologically, no changes were observed when the same fungal isolates were allowed to interact within them. However, 10 interactions between different fungal isolates showed mutual replacement with each fungus; capturing territory from the other. Contrastingly, 35 interactions resulted into complete replacement as one of the fungi was inhibited by rapid growth of the other fungus. In 46 interactions, formation of barrage was observed leading to deadlock type of interaction wherein both fungi have restricted growth. To study in details about the barrage formation, two fungal interactions were taken (i) T. coccinea vs. L. lactinea and (ii) T. coccinea vs. T. versicolor. Microscopic changes in the hyphal growth during interaction were observed. There was significant increase in the enzymatic activities including cellulase, xylanase and chitinase during in-vitro fungal–fungal interaction, suggesting the importance of such interactions for commercial enzyme production

Structural basis of terephthalate recognition by solute binding protein TphC

The presence of the gene encoding the solute binding protein TphC has been shown to permit the uptake of terephthalate (TPA), which is the breakdown product of Polyethylene terephthalate (PET) plastic. Here the authors present a structural characterization of TphC in both open and TPA-bound closed conformations