Abstract
Myxobacterial predation on bacteria has been investigated for several decades. However, their predation on fungi has received less attention. Here, we show that a novel outer membrane β-1,6-glucanase GluM from Corallococcus sp. strain EGB is essential for initial sensing and efficient decomposition of fungi during predation. GluM belongs to an unstudied family of outer membrane β-barrel proteins with potent specific activity up to 24,000 U/mg, whose homologs extensively exist in myxobacteria. GluM was able to digest fungal cell walls efficiently and restrict Magnaporthe oryzae infection of rice plants. Genetic complementation with gluM restored the fungal predation ability of Myxococcus xanthus CL1001, which was abolished by the disruption of gluM homolog oar. The inability to prey on fungi with cell walls that lack β-1,6-glucans indicates that β-1,6-glucans are targeted by GluM. Our results demonstrate that GluM confers myxobacteria with the ability to feed on fungi, and provide new insights for understanding predator-prey interactions. Considering the attack mode of GluM, we suggest that β-1,6-glucan is a promising target for the development of novel broad-spectrum antifungal agents.
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Acknowledgements
We would like to thank Prof. Xiaohua Mao and Prof. Huiqiang Lou for generously providing strains Myxococcus xanthus DK1622 and Neurospora crassa, Prof. Yifa Zhou for generously providing the β-1,6-glucan BIWP2, Prof. Yuezhong Li for the kind suggestions for gene knockout, Prof. Yufeng Yao and Prof. Daniel Wall and Prof. Ruifu Zhang for helpful manuscript suggestions. We are grateful to Prof. Josef Voglmeir for revising the manuscript. This work was supported by the Major State Basic Research Development Program of China (973 program, no. 2015CB150502), the National Natural Science Foundation of China (No. 31570059 and 31700054), the Postdoctoral Science Foundation of China (No. 2016M591859) and Jiangsu Agricultural science and technology innovation fund (CX(18)1003).
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Li, Z., Ye, X., Liu, M. et al. A novel outer membrane β-1,6-glucanase is deployed in the predation of fungi by myxobacteria. ISME J 13, 2223–2235 (2019). https://doi.org/10.1038/s41396-019-0424-x
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DOI: https://doi.org/10.1038/s41396-019-0424-x
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