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Andrew Santiago-Frangos

@asantiagofrangos.bsky.social
372 followers 378 following 20 posts

Asst Prof @Penn. CRISPR Biology & Applications | DNA folding and Bacterial/Archaeal defense systems | Biochem & CryoEM | #NIHMOSAIC K99/R00. web.sas.upenn.edu/sanfrango-lab

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Reposted by Andrew Santiago-Frangos
Gal Ofir @galofir.bsky.social · 17h
For a broader analysis of Tiamat homologs in Eukaryotes, @asantiagofrangos.bsky.social pre-printed their story back-to-back with us 😀
biorxiv.org
The bacterial antiphage protein Tiamat is an ATPase and DNase whose homologs are found across the tree of life
Bacteria and archaea encode hundreds of antiviral defense systems, some with homologs found in eukaryotic innate immunity. GHL ATPases like plant MORCs and prokaryotic Tiamat defend against viruses an...
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Reposted by Andrew Santiago-Frangos
Gal Ofir @galofir.bsky.social · 17h
A new plant-bacteria immunological connection in the first preprint of our group at @mpi-bio-fml.bsky.social @plantevolution.bsky.social! Straight from the top of Mt. Olympus ⛰️🦅 Led by Eirik @eiriklag.bsky.social, in collaboration with @geminiteamlab.bsky.social www.biorxiv.org/content/10.6...
Our preprint with the view from the top of the Olympus in the background
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 03/10/2026
Gal Ofir & colleagues provide additional evolutionary insights into Tiamat and determine its role during plant viral infections! See thread here:
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Reposted by Andrew Santiago-Frangos
Eirik Lågeide @eiriklag.bsky.social · 01/10/2026
Very excited to share the first preprint from my PhD with the community! This is also the first paper from the Plant Immunogenomics group with @galofir.bsky.social, so stay tuned for more! www.biorxiv.org/content/10.6... 1/n 🧵
biorxiv.org
NO VEIN is an ancestral immunity protein involved in plant-virus interaction
The conservation of immune systems from prokaryotes to eukaryotes can guide discovery of immunity genes across the tree of life. Most studies to date have focused on metazoan systems, while the extent...
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Reposted by Andrew Santiago-Frangos
Sorek Lab @soreklab.bsky.social · 02/10/2026
Andrew Santiago-Frangos and colleagues characterize Tiamat, a giant bacterial defense protein originally detected in the Millman 2022 study, and show that homologs of Tiamat are encoded in animals and plants. Nice to see the mystery of Tiamat starting to unravel
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Reposted by Andrew Santiago-Frangos
Chrystal Starbird @drstarbird.bsky.social · 01/10/2026
And… I am SO excited to share the first research preprint from my group! In this paper we determined several cryoEM structures to visualize the entire cell-to-cell bridging complex formed by TAM receptor and ligand, bringing into 3D a common graphical depiction. www.biorxiv.org/content/10.6...
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Congratulations to co-first authors Shirley Yuan and Yuri de Oliveira Silva, Balwina Koopal, @dangitvinh.bsky.social, Arav Nangia, and @jpkbravo.bsky.social! Thank you to the Burroughs Wellcome Fund, the NIH, Penn's CURF, ISTA, FWF, EMBO and HFSP. (11/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Plant NO VEIN is a Tiamat homolog with intact ATPase and nuclease domains. Elegant work from @eiriklag.bsky.social, colleagues, @geminiteamlab.bsky.social + @galofir.bsky.social labs find NOV knockdown impairs defense-gene induction during viral infection + more! : biorxiv.org/content/10.6... (9/11)
biorxiv.org
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
In prokaryotes, Tiamat genes often neighbour helicases (~14% of Tiamats, ~33% of Tiamat-like), DNA methyltransferases, and nucleases. We speculate Tiamat nicks DNA, a helicase unwinds it and Tiamat degrades the ssDNA (untested). Some neighbourhoods may instead act on RNA. (8/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Tiamat is modular. Tiamat-like proteins often swap the nuclease for helicases, peptidases, or other effectors; some fungal ones carry Het-6, a non-self sensor that triggers cell death. On a GHL ATPase tree, Tiamat groups with human SACSIN, mutated in the ataxia ARSACS. (7/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Balwina Koopal in the @jpkbravo.bsky.social lab purified B. cereus Tiamat. In vitro it hydrolyses ATP, cuts ssDNA at several sites, nicks duplex DNA far less efficiently, and doesn't detectably cut ssRNA. (6/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Its predicted structure: between an N-terminal ATPase and a C-terminal PD-(D/E)xK nuclease, we find TPR-like repeats, a new "Fold B" and a metalloprotease-like fold that is likely inactive. The ATPase and nuclease are predicted to dimerize, like an Hsp90 clamp. (5/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Chordates are the exception: 13% of these have Tiamat - all aquatic (80 from ray-finned fish), no Tiamats in any tetrapod analysed. A few eukaryotic Tiamats look bacterial, so we propose Tiamat crossed between prokaryotes and eukaryotes on several independent occasions. (4/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Searching thousands of proteomes, we find Tiamat is fairly common in eukaryotes, compared to prokaryotes. It's found in 78% of green plants, 50–80% of water molds, cnidarians and molluscs, and every rotifer, placozoan and sponge proteome analysed (only 10, 2 and 2). (3/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Seminal work from Millman and colleagues (2022) had found Tiamat by its enrichment in "defense islands". They showed B. cereus Tiamat gave modest defense against E. coli phage infection and required an intact ATPase site. The roles of its two DUF domains were unclear. (2/11)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 01/10/2026
Our lab's first preprint! The antiphage protein Tiamat is an ATPase and DNase with homologs across the tree of life. What started as undergrad Shirley Yuan's summer project grew into a paper and a collaboration with @jpkbravo.bsky.social's group. Link: www.biorxiv.org/content/10.6...
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 17/05/2026
First cryo-EM data collection of the Santiago-Frangos Lab, by Briana Cruga! Looking forward to visualizing how this DNA is folded to promote CRISPR adaptation 🔬🧬🦠
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Reposted by Andrew Santiago-Frangos
Tobias Warnecke @tobiaswarnecke.bsky.social · 08/09/2025
Please re-post: Interested in chromatin and its evolution? Good news! There's still time to join us in beautiful Catalonia (9-12 Dec) to discuss eukaryotic, bacterial, archaeal, and viral chromatin and how it all hangs together meetings.embo.org/event/24-evo... Abstract deadline: 30 September
meetings.embo.org
EvoChromo: Evolutionary approaches to research in chromatin
Chromatin is the complex of DNA, RNA and protein that is found making up the chromosomes in eukaryotic cells. Chromatin is essential for proper genome function and is involved in chromosome segregati…
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Reposted by Andrew Santiago-Frangos
Bronwyn Lucas @bronwynalucas.bsky.social · 25/07/2025
PhD student @lainahall.bsky.social will be giving a talk about our measurements of FIB-milling damage in cryo-lamellae (with new data!) at M&M on Tuesday next week.
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 02/07/2025
Awesome structural biology with a unique Cas interference-adaptation supercomplex to understand how these systems adapt to phage infection!
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Reposted by Andrew Santiago-Frangos
Anna Kanevskaya @annakanevskaya.bsky.social · 07/04/2025
News from the world of pAgos: We explored a distinct clade of short pAgos associated with HNH nuclease partners, which we named SPARHA, and discovered that they protect bacteria from phages and plasmids via abortive infection. Upon activation, SPARHA oligomerizes, forming filaments. A long 🧵
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 22/06/2025
New cryo-EM ❄️🔬 structures shine light on key steps in CRISPR-based adaptive immunity! Viral DNA binding to the Cas1-2/3 integrase induces a conformational change needed to recruit the integrase to the CRISPR. We capture how CRISPR repeat is unwound to allow complete integration. Congrats Will + co!
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Reposted by Andrew Santiago-Frangos
Sternberg Lab @sternberglab.bsky.social · 26/03/2025
Hello BlueSky! Inaugural post here from the Sternberg Lab. We're excited to share our latest work, in which we teamed up with the @WiedenheftLab to study how DRT9 reverse transcriptases provide antiviral immunity. Here’s what we found: www.biorxiv.org/content/10.1...
biorxiv.org
Protein-primed DNA homopolymer synthesis by an antiviral reverse transcriptase
Bacteria defend themselves from viral predation using diverse immune systems, many of which sense and target foreign DNA for degradation. Defense-associated reverse transcriptase (DRT) systems provide...
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Reposted by Andrew Santiago-Frangos
Jason Shepherd @jasonsynaptic.bsky.social · 11/02/2025
Scientists, now more than ever, need to explain their work to the public. Many years ago now, I gave a TEDMED talk about my lab’s research. 🧠 🧪 www.tedmed.com/talks/show?i...
tedmed.com
How an ancient virus spread the ability to remember
Do you remember your oldest memory? Jason Shepherd clearly recalls a childhood filled with questioning the world around him, which naturally lead to a life of scientific discovery. As a Neurobiologist...
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Reposted by Andrew Santiago-Frangos
Patrick R. Secor @prsecor.bsky.social · 07/02/2025
Published on my birthday 🎉 Another paper in collaboration with @themaxwelllab.bsky.social Phage reprogramming of Pseudomonas aeruginosa amino acid metabolism drives efficient phage replication doi.org/10.1128/mbio... 🦠🧫🧪🧬
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Reposted by Andrew Santiago-Frangos
Andrea Andress Huacachino, PhD @chemistandrea.bsky.social · 02/12/2024
As my first on Bluesky post, I'm glad to announce my work on PFOA has been published! Please check it out! During our work we have uncovered a new mechanism which implicates PFOA in hyperandrogenism, as has been speculated in the past! www.sciencedirect.com/science/arti...
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Reposted by Andrew Santiago-Frangos
Lander Lab @landerlab.bsky.social · 22/01/2025
Just because it's a homo-oligomer, don't assume it's symmetric! @benjabsnt.bsky.social & collaborators used cryo-EM to study the transthyretin (TTR) tetramer (55 kDa), shedding light on its misfolding pathways linked to amyloid disease. Now in peer-reviewed form: www.nature.com/articles/s41...
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Reposted by Andrew Santiago-Frangos
Matthew Freeman @mjafreeman.bsky.social · 19/11/2024
Here’s my spreadsheet of starter packs (>80!) related to broadly ‘mechanistic biology’ plus some intriguing extras Complete with collective nouns I’ve been tracking these but now can’t keep up Hope it’s helpful 2/2 docs.google.com/spreadsheets...
docs.google.com
@mjafreeman.bsky.social's BlueSky starter packs for 'mechanistic' biologists
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Reposted by Andrew Santiago-Frangos
Malcolm White @mfwhite2.bsky.social · 18/11/2024
If you work on bacterial immune systems, this founding paper by Burroughs and Aravind is a must-read (and must-cite). pubmed.ncbi.nlm.nih.gov/32868406/
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Reposted by Andrew Santiago-Frangos
Joscelyn Mejías, PhD @jcmejias.bsky.social · 17/11/2024
I started a list of MOSAIC scholars to help find and support each other. I'm sure I've missed many people, lmk if you want to be added! go.bsky.app/9Ui711k
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Reposted by Andrew Santiago-Frangos
Zamin Iqbal @zaminiqbal.bsky.social · 17/11/2024
Bacterial DNA encapsidation by viruses and virus-like particles appears to be widespread in the microbiome with up to 5.4% of capsid-packaged DNA in the gut virome being of bacterial (non-prophage) origin. www.biorxiv.org/content/10.1... 2/2
biorxiv.org
Large scale capsid-mediated mobilisation of bacterial genomic DNA in the gut microbiome
Here, we present a novel approach to study packaging and mobilisation of bacterial DNA in complex microbial communities, such as the human gut microbiome, by viral or virus-like capsids. Transducing b...
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Reposted by Andrew Santiago-Frangos
Dr. Arnaldo Díaz @ajdiazphd.bsky.social · 11/11/2024
Hello 👋🏼—I’m a first-gen college student from Puerto Rico & currently serve as an Associate Dean at a major medical center. I’ve dedicated my career to developing programs focused on recruiting/training STEM leaders. I’m passionate about mentoring & providing opportunities for all to thrive.
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 13/11/2024
Excited to be going to ABRCMS this year! Looking forward to meeting new (and old) friends and sharing work! :D
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 12/01/2024
I'll also be at the BPS and ASBMB meetings this year if anyone wants to chat or learn more in person! 🤓
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 12/01/2024
📢I'm hiring a Postdoc to join me at Dept. of Biology at UPenn! We'll use bioinformatics 🖥️, biochem 🧪, and cryo-EM ❄️🔬, to study how CRISPR systems work & applications. Work on cool science with a supportive mentor! I'm still building up my Bluesky profile, so Reposts are appreciated!!!
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 05/01/2024
😁😁😁
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 04/01/2024
Thank you so much Edwin!! :)
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Andrew Santiago-Frangos @asantiagofrangos.bsky.social · 04/01/2024
The Santiago-Frangos lab is open and ready to do some exciting research on CRISPR biology and CRISPR applications! Ecstatic to be on UPenn's campus amongst such a supportive group of excellent scientists! 🤓
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