pdhsu.bsky.social
@pdhsu.bsky.social
Read the full preprint below 👇 If you're interested in the interface of bioengineering, DNA and virtual cell foundation models, and agentic reasoning, shoot me a note. We're hiring postdocs and ML researchers and starting some crazy new projects

www.biorxiv.org/content/10.1...
Megabase-scale human genome rearrangement with programmable bridge recombinases
Bridge recombinases are a class of naturally occurring RNA-guided DNA recombinases. We previously demonstrated they can programmably insert, excise, and invert DNA in vitro and in bacteria. Here, we r...
www.biorxiv.org
May 15, 2025 at 1:47 PM
This work was a wonderful collaboration with Silvana Konermann, led by star graduate student Nick Perry with key contributions from the amazing Liam Bartie, Dhruva Katrekar, Gabe Gonzalez, Matt Durrant, James Pai, Alison Fanton, Masa Hiraizumi, Chiara Ricci-Tam, and Hiroshi Nishimasu

Arc is on 🔥
May 15, 2025 at 1:47 PM
Bridge recombinases can modify the genome from single gene insertions to megabase-sized rearrangements

We're excited about programmable genome design at unprecedented length scales, especially when combined with AI-generated DNA sequences of high complexity (e.g. Evo 2)
May 15, 2025 at 1:47 PM
Most people think of recombinases for payload insertion (e.g. of CARs or corrective genes)

We provide a therapeutic proof-of-concept with bridge-mediated excision of the BCL11A enhancer for sickle cell anemia and of expanded repeat sequences found in Friedreich's ataxia
May 15, 2025 at 1:47 PM
But unlike other tools, bridge editing is not limited to insertion! We use IS622 for programmable, precise, and scarless genome rearrangements, inverting up to 0.93 Mb and excising up to 0.13 Mb
May 15, 2025 at 1:47 PM
We then performed a systematic deep mutational scan of IS622 and combined a rationally engineered, high activity recombinase mutant with our enhanced bridge RNAs to demonstrate 20% insertion efficiency into the human genome
May 15, 2025 at 1:47 PM
Using these enhanced bridge RNAs, we discovered design principles for maximizing the specificity of insertion into the human genome, achieving as high as 82% specificity genome-wide
May 15, 2025 at 1:47 PM
In a tour de force of molecular engineering, our team conducted computational ortholog mining, human cell activity screening, and structure-guided bridge RNA engineering to enhance the activity of IS622, a bridge system that showed promising but low activity in human cells
May 15, 2025 at 1:47 PM
Bridge recombination systems are elegant molecular tools that utilize a recombinase enzyme and a programmable bridge RNA to "bridge" and recombine two distinct DNA molecules

This is a universal mechanism for insertion, excision, or inversion of any two DNA sequences
May 15, 2025 at 1:47 PM
This was an insane team effort between Arc and Nvidia that convened machine learning and computational biology researchers across Stanford, UC Berkeley, and UCSF. Especially grateful to Jensen Huang for his belief and support of this vision and labor of love, and the entire Evo 2 team below
February 19, 2025 at 4:37 PM
Finally, if Evo 2 sounded exciting, @arcinstitute.org
is hiring. Check out open Arc jobs at arcinstitute.org/jobs or just email me directly. Our research group is hiring in molecular machine learning and the interface of computational and synthetic biology
February 19, 2025 at 4:35 PM
Here are some useful links:

Evo 2 preprint: arcinstitute.org/manuscripts/...
Evo Designer: arcinstitute.org/tools/evo/ev...
Evo Mech Interp Visualizer: arcinstitute.org/tools/evo/ev...
Evo 2 code: github.com/arcinstitute...
Manuscript | Arc Institute
Arc Institute is a independent nonprofit research organization headquartered in Palo Alto, California.
arcinstitute.org
February 19, 2025 at 4:35 PM
DNA is just the beginning. In middle school, we learn that genotype and the environment collaborate to create phenotype. We are incorporating Evo 2's understanding of genetic variation into Arc's virtual cell models that can be used for drug discovery and target ID
February 19, 2025 at 4:35 PM
We're excited to see what the research community builds on top of this foundation model to enable the biological "app store"
February 19, 2025 at 4:35 PM
Beyond pretraining scale, Evo 2 also scales at inference time. We demonstrate "generative epigenomics" by controlling the position and width of predicted chromatin accessibility to encode Morse code messages in the epigenome. Can you guess what's written below? .- .-. -.-.
February 19, 2025 at 4:35 PM