Alexander Leydon (He/him)

Many thanks to @sarah-guiziou.bsky.social and Cassandra Maranas for building out the amazing Integrase toolkit from which we sourced our parts, and to Dr. Jennifer Nemhauser for her unwavering support.

This tool builds on traditional T-DNA loss of functions, rescuing them with a switchable DNA target. This unlocks many essential genes for further study with just two additional T-DNAs. Inducible and cell type specific drivers allow testing in your tissues/times of choice.

A Hot-Swappable Genetic Switch: Building an Inducible and Trackable Functional Assay for the Essential Gene MEDIATOR 21 Essential genes, estimated to be approximately 20% of the Arabidopsis genome, are broadly expressed and required for reproductive success. They are difficult to study, as interfering with their function leads to premature death. Transcription is one of the essential functions of life, and the multiprotein Mediator complex coordinates the regulation of gene expression at nearly every eukaryotic promoter. In this study, we focused on a core mediator component called MEDIATOR21 (MED21), which is required for activation of transcription. Our previous work has also shown a role for MED21 in repression of gene expression through its interaction with a corepressor protein. Here, we sought to differentiate the role MED21 plays in activation versus repression using the model plant Arabidopsis. As mutations in MED21 lead to embryo-lethal phenotypes, we constructed a set of synthetic switches using PhiC31 serine integrases to create an “on-to-off” inducible loss-of-function MED21 in a nonessential tissue. Our technology, which we call Integrase Erasers, enabled med21 mutant plants to survive into adulthood by ablating protein expression selectively in lateral root primordia, allowing quantification and characterization of med21 mutant phenotypes in a postembryonic context. In addition, we engineered chemical induction of the Integrase Eraser to ablate MED21 expression in whole seedlings at a user-specified time point. Finally, we extended this technology to build a hot-swappable Integrase Isoform Switch where expression of the integrase toggled cells from expressing wild-type MED21 to expressing MED21 sequence variants. Our analysis of the entire set of new integrase-based tools demonstrates that this is a highly efficient and robust approach to the study of essential genes.

I am very excited to share our recent paper that has just been published at [ACS Synthetic Biology](pubs.acs.org/doi/full/10....). An integrase based tool for one demand loss of function and isoform swapping in plants. Impressive perseverance from first author Isabella Watson in 1st Publication.

Please consider making a public comment opposing the possibility of making NIH directors, program officers, and other staff (e.g. SRO, GMS) political appointees. This only took me ~90 seconds. Please repost. Thanks 👍

Join researchers across the country in fighting restrictions on the NIH Please click the link to complete this form.

Academic workers across the country are organizing to call on our congressional representatives on Thursday, 1/30, at 3pm ET / 12pm PT to demand these restrictions be lifted immediately.
There will be a training over zoom at the beginning of the event.
Join us!
form.jotform.com/250226137228...

A function of TPL/TBL1-type corepressors is to nucleate the assembly of the preinitiation complex Corepressors in the TPL/TBL1-type family prime genes for rapid activation by facilitating assembly of the transcription preinitation complex, including TFI

Excited to share our recent study is out at the Journal of Cell Biology! @jcellbiol.bsky.social, LisH domains are short but powerful domains in priming transcription by corepressors: doi.org/10.1083/jcb..... Very proud of our NemLab team!!

Study pointing towards a role for regulated ubiquitination of TPL/TPRs in developmental transitions

Conserved effector families render Phytophthora species vulnerable to recognition by NLR receptors in nonhost plants Nature Communications - Genus Phytophthora threat various plant species including fruit, vegetable, and flower crops. The authors report that some NLRs recognize conserved effector families of...

Conserved effector families render Phytophthora species vulnerable to recognition by NLR receptors in nonhost plants
Soohyun Oh et al. 2024 rdcu.be/d1f33

Galvanin is an electric-field sensor for directed cell migration Directed cell migration is critical for the rapid response of immune cells, such as neutrophils, following tissue injury or infection. Endogenous electric fields, generated by the disruption of the tr...

Very cool new preprint from colleague Nathan Belliveau and team in the Theriot Lab! - Galvanin is an electric-field sensor for directed cell migration

A dose-dependent bimodal switch by homologous Aux/IAA transcriptional repressors Aux/IAA proteins, repressors in the auxin signaling pathway, exhibit varying affinities for the co-repressor TPL based on the EAR-motif syntax. Aux/IAAs with weaker TPL affinities function as dose-dep...

A fascinating recent paper "A dose-dependent bimodal switch by homologous Aux/IAA transcriptional repressors". This work highlights how IAA-TPL affinities can drive cell state changes within the cellular mixture of IAAs! So cool!

Assistant Professor, Tenure Track
botany.fyi/wuontl

The School of Integrative Plant Science at Cornell University is seeking a Plant Synthetic Biologist, whose research is centered on synthetic biology involving photosynthetic organisms.
#Botany #PlantScience #PlantSciJobs

A conserved function of corepressors is to nucleate assembly of the transcriptional preinitiation complex. bioRxiv - the preprint server for biology, operated by Cold Spring Harbor Laboratory, a research and educational institution

Excited to share a preprint for our newest manuscript on the TPL family of corepressor! Very proud of our team and thankful for all our amazing collaborators.

I’m organizing a session with @cvoiniciuc on “New Methods to Accelerate Plant Synthetic Biology” at ICAR SD this year @naascarabidopsis.bsky.social !We want to give you a spot to talk about how you're building and learning with plants, so make sure to submit your abstracts!

Wading into bluesky to celebrate #LisH domains! Did you know they do more than dimerize? They are also potent repressors of transcription. Román Ramos Báez @sensitiveroots.bsky.social, Jennifer Nemhauser and I explored this in our last paper.