Rational Structure-Based Design of Bright GFP-Based Complexes with Tunable Dimerization.

Fluorescent proteins are transformative tools; thus, any brightness increase is a welcome improvement. We invented the "vGFP strategy" based on structural analysis of GFP bound to a single-domain antibody, predicting tunable dimerization, enhanced brightness (ca. 50%), and improved pH resistance. We verified all of these predictions using biochemistry, crystallography, and single-molecule studies. We applied the vsfGFP proteins in three diverse scenarios: single-step immunofluorescence in vitro (3× brighter due to dimerization); expression in bacteria and human cells in vivo (1.5× brighter); and protein fusions showing better pH resistance in human cells in vivo. The vGFP strategy thus allows upgrading of existing applications, is applicable to other fluorescent proteins, and suggests a method for tuning dimerization of arbitrary proteins and optimizing protein properties in general.

Sequencing of E. coli strain UTI89 on multiple sequencing platforms.

OBJECTIVES: The availability of matched sequencing data for the same sample across different sequencing platforms is a necessity for validation and effective comparison of sequencing platforms. A commonly sequenced sample is the lab-adapted MG1655 strain of Escherichia coli; however, this strain is not fully representative of more complex and dynamic genomes of pathogenic E. coli strains. DATA DESCRIPTION: We present six new sequencing data sets for another E. coli strain, UTI89, which is an extraintestinal pathogenic strain isolated from a patient suffering from a urinary tract infection. We now provide matched whole genome sequencing data generated using the PacBio RSII, Oxford Nanopore MinION R9.4, Ion Torrent, ABI SOLiD, and Illumina NextSeq sequencers. Together with other publically available datasets, UTI89 has a nearly complete suite of data generated on most second- and third-generation sequencers. These data can be used as an additional validation set for new sequencing technologies and analytical methods. More than being another E. coli strain, however, UTI89 is pathogenic, with a 10% larger genome, additional pathogenicity islands, and a large plasmid, features that are common among other naturally occurring and disease-causing E. coli isolates. These data therefore provide a more medically relevant test set for development of algorithms.

Intrinsic Xenobiotic Resistance of the Intestinal Stem Cell Niche.

The gut absorbs dietary nutrients and provides a barrier to xenobiotics and microbiome metabolites. To cope with toxin exposures, the intestinal epithelium is one of the most rapidly proliferating tissues in the body. The stem cell niche supplies essential signaling factors including Wnt proteins secreted by subepithelial myofibroblasts. Unexpectedly, therapeutically effective doses of orally administered PORCN inhibitors that block all Wnt secretion do not affect intestinal homeostasis. We find that intestinal myofibroblasts are intrinsically resistant to multiple xenobiotics, including PORCN inhibitors and the anthracycline antibiotic doxorubicin. These myofibroblasts have high expression of a subset of drug transporters; knockout of Mrp1/Abcc1 enhances drug sensitivity. Tamoxifen administration to Rosa26CreERT2;mT/mG mice visually highlights the drug-resistant intestinal stromal compartment and identifies small populations of drug-resistant cells in lung, kidney, and pancreatic islets. Xenobiotic resistance of the Wnt-producing myofibroblasts can protect the intestinal stem cell niche in the face of an unpredictable environment.