Biology subjects

Cornish, V. W.

Publications and source records attributed to Cornish, V. W..

3 recordsLinked to original sources

bioRxiv2026

Pseudomonas aeruginosa R-bodies deliver an ADP deaminase toxin

Diverse bacteria produce proteinaceous polymeric coils called R-bodies (refractile bodies), which extend into ~10 m-long needles in response to environmental triggers. It has been proposed that R-bodies deliver toxins intracellularly after such bacteria are ingested by eukaryotes, but intra-host extension of R-bodies has not been directly observed and these toxins remain unidentified. We use Pseudomonas aeruginosa PA14 and Dictyostelium discoideum to show that R-bodies extend within amoebae. We also identify a novel toxin, DeaR (deaminase associated with the R-body), which contributes to predation resistance and forms a near-megadalton dodecamer with ADP deaminase activity that alters purine metabolism. Our findings elucidate the molecular basis of R-body-mediated toxicity during PA14 infection and provide a paradigm for understanding the potential of cytotoxic effectors delivered by R-bodies (CEDRs) in interkingdom interactions.

microbiology↗

bioRxiv2021

FRAME-tags: genetically encoded fluorescent markers for multiplexed barcoding and time-resolved tracking of live cells

Cellular barcodes offer critical tools for tracking cellular identity in biological systems. Although genetically encoded fluorescent barcodes are ideal for real-time tracking, their scalability is constrained by the broad, overlapping emission spectra characteristic of fluorescent proteins (FPs). Here, we describe a palette of genetically encoded fluorescent barcodes called FRAME-tags, which break this scalability barrier by encoding barcode identity as unique FP expression ratios. FRAME-tags use -1 programmed ribosomal frameshifting RNA motifs to precisely control the translational output of multiple FPs from a single mRNA, leading to extremely narrow and resolvable ratios of the corresponding cellular fluorescence distributions. With this platform, we constructed 20 resolvable FRAME-tags in yeast using just two FPs, and further demonstrated that 100 or more distinguishable FRAME-tags could be made by the addition of a third FP. We used FRAME-tags to map the dynamic fitness landscape of yeast co-cultures, and to characterize the expression pattern of 20 yeast promoters in multiplex across diverse conditions. FRAME-tags offer a valuable new tool for cellular barcoding that enables time-resolved characterization of complex biological systems using widely available fluorescence detection techniques and a minimal number of spectral channels.

synthetic biology↗

bioRxiv2018

D-amino acid-mediated translation arrest is modulated by the identity of the incoming aminoacyl-tRNA

A complete understanding of the determinants that restrict D-amino acid incorporation by the ribosome, which is of interest to both basic biologists as well as the protein engineering community, remains elusive. Previously, we demonstrated that D-amino acids are successfully incorporated into the C-terminus of the nascent polypeptide chain. Ribosomes carrying the resulting peptidyl-D-aminoacyl-tRNA (peptidyl-D-aa-tRNA) donor substrate, however, partition into subpopulations that either undergo translation arrest through inactivation of the ribosomal peptidyl-transferase center (PTC) or remain translationally competent. The proportion of each subpopulation is determined by the identity of the D-amino acid sidechain. Here, we demonstrate that the identity of the aminoacyl-tRNA (aa-tRNA) acceptor substrate that is delivered to ribosomes carrying a peptidyl-D-aa-tRNA donor further modulates this partitioning. Our discovery demonstrates that it is the pairing of the peptidyl-D-aa-tRNA donor and the aa-tRNA acceptor that determines the activity of the PTC. Moreover, we provide evidence that both the amino acid and tRNA components of the aa-tRNA donor contribute synergistically to the extent of arrest. The results of this work deepen our understanding of the mechanism of D-amino acid-mediated translation arrest and how cells avoid this precarious obstacle, reveal similarities to other translation arrest mechanisms involving the PTC, and provide a new route for improving the yields of engineered proteins containing D-amino acids.

biochemistry↗