Protein and DNA Conformational Changes Contribute to Specificity of Cre Recombinase.

Cre, a conservative site-specific tyrosine recombinase, is a powerful gene editing tool in the laboratory. Expanded applications in human health are hindered by lack of understanding of the mechanism by which Cre selectively binds and recombines its cognate sequences. This knowledge is essential for retargeting the enzyme to new sites and for mitigating effects of off-target recombination.

Transmembrane channel-like 4 and 5 proteins at microvillar tips are potential ion channels and lipid scramblases.

Microvilli-membrane bound actin protrusions on the surface of epithelial cells-are sites of critical processes including absorption, secretion, and adhesion. Increasing evidence suggests microvilli are mechanosensitive, but underlying molecules and mechanisms remain unknown. Here, we localize transmembrane channel-like proteins 4 and 5 (TMC4 and 5) and calcium and integrin binding protein 3 (CIB3) to microvillar tips in intestinal epithelial cells, near glycocalyx insertion sites.

Dynamics in Cre-loxP site-specific recombination.

Cre recombinase is a phage-derived enzyme that has found utility for precise manipulation of DNA sequences. Cre recognizes and recombines pairs of loxP sequences characterized by an inverted repeat and asymmetric spacer. Cre cleaves and religates its DNA targets such that error-prone repair pathways are not required to generate intact DNA products.

Complexes of vertebrate TMC1/2 and CIB2/3 proteins form hair-cell mechanotransduction cation channels.

Calcium and integrin-binding protein 2 (CIB2) and CIB3 bind to transmembrane channel-like 1 (TMC1) and TMC2, the pore-forming subunits of the inner-ear mechano-electrical transduction (MET) apparatus. These interactions have been proposed to be functionally relevant across mechanosensory organs and vertebrate species. Here we show that both CIB2 and CIB3 can form heteromeric complexes with TMC1 and TMC2 and are integral for MET function in mouse cochlea and vestibular end organs as well as in zebrafish inner ear and lateral line.

Mapping protein-polymer conformations in bioconjugates with atomic precision.

Rational design of protein-polymer bioconjugates is hindered by limited experimental data and mechanistic understanding on interactions between the two. In this communication, nuclear magnetic resonance (NMR) paramagnetic relaxation enhancement (PRE) reports on distances between paramagnetic spin labels and NMR active nuclei, informing on the conformation of conjugated polymers. H/N-heteronuclear single quantum coherence (HSQC) NMR spectra were collected for ubiquitin (Ub) modified with block copolymers incorporating spin labels at different positions along their backbone.

A Single Salt Bridge in VIM-20 Increases Protein Stability and Antibiotic Resistance under Low-Zinc Conditions.

To understand the evolution of Verona integron-encoded metallo-β-lactamase (VIM) genes () and their clinical impact, microbiological, biochemical, and structural studies were conducted. Forty-five clinically derived VIM variants engineered in a uniform background and expressed in afforded increased resistance toward all tested antibiotics; the variants belonging to the VIM-1-like and VIM-4-like families exhibited higher MICs toward five out of six antibiotics than did variants belonging to the widely distributed and clinically important VIM-2-like family. Generally, maximal MIC increases were observed when cephalothin and imipenem were tested.