Microorganisms
colonizing the plant rhizosphere provide a number
of beneficial functions for their host. Although an increasing number
of investigations clarified the great functional capabilities of rhizosphere
microbial communities, the understanding of the precise mechanisms
underlying the impact of rhizosphere microbiome assemblies is still
limited. Also, not much is known about the various beneficial functions
of the rhizosphere microbiome. In this review, we summarize the current
knowledge of biotic and abiotic factors that shape the rhizosphere
microbiome as well as the rhizosphere microbiome traits that are beneficial
to plants growth and disease-resistance. We give particular emphasis
on the impact of plant root metabolites on rhizosphere microbiome
assemblies and on how the microbiome contributes to plant growth,
yield, and disease-resistance. Finally, we introduce a new perspective
and a novel method showing how a synthetic microbial community construction
provides an effective approach to unravel the plant–microbes
and microbes–microbes interplays.
Acid-sensing ion channels (ASICs) are neuronal voltage-independent Na+ channels that are activated by extracellular acidification. ASICs play essential roles in a wide range of physiological processes, including sodium homeostasis, synaptic plasticity, neurodegeneration, and sensory transduction. Mambalgins, a family of three-finger toxins isolated from black mamba venom, specifically inhibit ASICs to exert strong analgesic effects in vivo, thus are thought to have potential therapeutic values against pain. However, the interaction and inhibition mechanism of mambalgin on ASICs remains elusive. Here, we report a cryo-electron microscopy (cryo-EM) structure of chicken ASIC1a (cASIC1a) in complex with mambalgin-1 toxin at 5.4 Å resolution. Our structure provides the first experimental evidence that mambalgin-1 interacts directly with the extracellular thumb domain of cASIC1a, rather than inserting into the acid-sensing pocket, as previously reported. Binding of mambalgin-1 leads to relocation of the thumb domain that could disrupt the acidic pocket of cASIC1a, illustrating an unusual inhibition mechanism of toxins on ASIC channels through an allosteric effect. These findings establish a structural basis for the toxicity of the mambalgins, and provide crucial insights for the development of new optimized inhibitors of ASICs.
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