Biology subjects

Legault, S.

Publications and source records attributed to Legault, S..

4 recordsLinked to original sources

bioRxiv2026

PANCS-Inhibitors: A rapid method to directly select for protein-protein interaction inhibitors

Aberrant protein-protein interactions (PPIs) drive myriad diseases. Inhibiting these PPIs often relies on discovering molecules that bind to one of the proteins and hoping that this binding inhibits the PPI. Molecular binder discovery often takes months, but a discovery process that ensures that the resulting molecule not only binds a target protein, but selectively inhibits a target PPI, could dramatically accelerate these endeavors. Here, we develop Phage-Assisted Non-Continuous Selection of PPI Inhibitors (PANCS-Inhibitors): a rapid screening platform that directly selects for molecules capable of disrupting a pre-formed PPI. We demonstrate this new platform using three clinically relevant oncogenic PPIs: KRas-Raf, Mdm2-p53, and Myc-Max. PANCS-Inhibitors can be used to both improve known PPI inhibitors and for de novo discovery of mini-protein PPI inhibitors that function in mammalian cells. This platform has the potential to rapidly generate inhibitors for many clinically relevant PPIs, which can be used as starting points for therapeutic development.

synthetic biology↗

bioRxiv2026

Rearing Istocheta aldrichi (Diptera: Tachinidae) from field-collected Japanese beetles (Popillia japonica): 1. Methods to improve insect collection and parasitoid pupariation

Istocheta aldrichi (Diptera: Tachinidae), a specialist parasitoid of the invasive Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae), was released to eastern North America in the 1920s as part of a classical biological control program. Further releases are being considered in different regions of North America and Europe where P. japonica is establishing. Successful releases of the biocontrol agent depend on identifying efficient techniques for collecting parasitized hosts from the field and rearing the parasitoid through diapause to obtain I. aldrichi adults. In this study, we evaluated how the collection date, the collection method (hand-picking vs. regular traps vs. modified traps) and rearing conditions (food provision and substrate type) of parasitized hosts influence I. aldrichi pupariation and emergence. The proportion of parasitized beetles yielding I. aldrichi puparia decreased considerably as the season progressed. Rearing conditions immediately after collection influenced both puparium yield and quality: withholding food from parasitized P. japonica slightly increased puparium yield but reduced puparium weight, while the effect of food provision on subsequent overwintering survival depended on rearing substrate. Finally, simple modifications to commercial traps (larger, ventilated, containers with added food source and substrate) collected more beetles than regular traps and promoted successful development of the parasitoid to the puparium stage. Our results are used to suggest basic guidelines for collecting and rearing I. aldrichi in experimental research and applied biological control of P. japonica.

ecology↗

bioRxiv2026

Rearing Istocheta aldrichi (Diptera: Tachinidae) from field-collected Japanese beetle (Popillia japonica): methods to improve overwintering, adult emergence and longevity

Istocheta aldrichi (Diptera: Tachinidae) is a specialist parasitoid of the invasive Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae). Research and releases for biological control depend on field collecting parasitized hosts and rearing the parasitoid through diapause to obtain I. aldrichi adults. This study investigated how rearing practices before, during and after the seasonal overwintering period affected the proportion of I. aldrichi pupae that emerged as adults, the timing of parasitoid emergence, and their longevity. Increasing cold exposure duration during overwintering increased adult I. aldrichi emergence from puparia and reduced development time after transfer to warm conditions. Adult I. aldrichi emergence from overwintered puparia depended on interactions between overwintering environment (indoors vs. outdoors), spring thermal regime, and the timing of host collection in the previous season. Burying puparia in the soil in late summer/early fall resulted in higher subsequent adult I. aldrichi emergence. Manipulating spring temperatures in controlled environments allowed parasitoid emergence to be staggered over several weeks without reducing emergence success. Emergence under outdoor spring conditions was unreliable. Adult longevity was affected by temperature and diet: cooler conditions extended lifespan, honey-water increased longevity relative to pollen alone or honey-water and pollen together. These results provide a foundation to further improve I. aldrichi rearing techniques for use in experimental research and applied biological control of P. japonica.

ecology↗

bioRxiv2025

Mapping Functional Dynamics Hotspots for Protein Engineering with NMR Peak Intensity Analysis

Structural dynamics play a crucial role in protein function, and tuning these dynamics through mutagenesis has emerged as a promising strategy for enhancing activity. However, identifying dynamics hotspots for protein engineering remains a labor-intensive challenge. Here, we demonstrate that NMR peak intensity analysis--a rapid, qualitative method with residue-level resolution--can identify functionally relevant dynamic regions with high precision. Using a family of red fluorescent proteins (RFPs) as a case study, we reveal that flexibility in specific regions of their structures correlates with function. Specifically, as quantum yield increases, the side of the {beta}-barrel closest to the chromophore phenolate moiety becomes more rigid, while the opposite side, closest to the acylimine group, gains flexibility. Notably, the phenolate face corresponds to a mutational hotspot frequently targeted in directed evolution campaigns aimed at enhancing brightness, underscoring its functional significance. B-factor analysis of non-cryogenic X-ray crystal structures further supports our findings. Our results establish NMR peak intensity analysis as a promising tool for mapping functional dynamics hotspots to guide protein engineering campaigns.

biophysics↗