A mosaic of cross-phylum chemical interactions occurs between all metazoans and their microbiomes. A number of molecular families known to be produced by the microbiome have a profound impact on the balance between health and disease 1-9. Considering the diversity of the human microbiome, numbering over 40,000 operational taxonomic units 10 , the impact of the microbiome on the chemistry of an entire animal remains underexplored. In this study, mass spectrometry informatics and data visualization approaches 11-13 were used to provide an assessment of the impacts of the microbiome on the chemistry of an entire mammal by comparing metabolomics data from germ-free (GF) and specific pathogen Reprints and/or permissions can be provided by R. Quinn or P.C. Dorrestein.
Multifunctional living materials are attractive due to their powerful ability to self-repair and replicate. However, most natural materials lack electronic functionality. Here we show that an electric field, applied to electricity-producing
Geobacter sulfurreducens
biofilms, stimulates production of previously unknown cytochrome OmcZ nanowires with 1,000-fold higher conductivity (30 S/cm), and 3-fold higher stiffness (1.5 GPa), than the cytochrome OmcS nanowires that are important in natural environments. Using chemical imaging-based multimodal nanospectroscopy, we correlate protein structure with function, and observe pH-induced conformational switching to β-sheets in individual nanowires, which increases their stiffness and conductivity by 100-fold due to enhanced π-stacking of heme groups; this was further confirmed by computational modelling and bulk spectroscopic studies. These nanowires can transduce mechanical and chemical stimuli into electrical signals to perform sensing, synthesis and energy production. These findings of biologically-produced, highly-conductive protein nanowires may help to guide the development of seamless, bidirectional interfaces between biological and electronic systems.
SummaryEhCaBP1, a calcium-binding protein of the parasite Entamoeba histolytica, is known to participate in cellular processes involving actin filaments. This may be due to its direct interaction with actin. In order to understand the kinetics of EhCaBP1 in such processes, its movement was studied in living cells expressing GFP-EhCaBP1. The results showed that EhCaBP1 accumulated at phagocytic cups and pseudopods transiently. The time taken for appearance and disappearance of EhCaBP1 was found to be around 12 s. Site-directed mutagenesis was used to generate an EhCaBP1 mutant with reduced Ca 2+ -and G-actin binding ability without any defect in its ability to bind F-actin. The overexpression of this mutant EhCaBP1 in the E. histolytica trophozoites resulted in the impairment of erythrophagocytosis, uptake of bacterial cells, killing of target cells but not fluidphase pinocytosis. However, the mutant protein was still found to transiently localize with F-actin at the phagocytic cups and pseudopods. The mutant protein displayed reduced ability to activate endogenous kinase(s) suggesting that phagosome formation may require Ca 2+
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