Joshua Pajak
@joshuapajak.bsky.social
American Cancer Society Postdoctoral fellow and structural biologist in the @briankelch.bsky.social lab at UMass Chan Medical school. I study ATPases and DNA replication/repair. Phage and MD simulations were my first scientific love. he/him/his
Pinned
PNAS
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans...
www.pnas.org
My paper on nucleotide exchange in RFC is now available at PNAS! www.pnas.org/doi/10.1073/...
Should you read if you already read our preprint? Yes!
Two big updates made during peer-review include:
Should you read if you already read our preprint? Yes!
Two big updates made during peer-review include:
Reposted by Joshua Pajak
We are seeking postdoctoral researchers to study viral RNA and macromolecular complexes using X-ray crystallography, cryo-EM, and biochemical methods.
Structural biology experience is required. Interested candidates should send a CV, a brief research statement, and 2–3 references to kaychoi@iu.edu.
Structural biology experience is required. Interested candidates should send a CV, a brief research statement, and 2–3 references to kaychoi@iu.edu.
November 16, 2025 at 9:17 PM
We are seeking postdoctoral researchers to study viral RNA and macromolecular complexes using X-ray crystallography, cryo-EM, and biochemical methods.
Structural biology experience is required. Interested candidates should send a CV, a brief research statement, and 2–3 references to kaychoi@iu.edu.
Structural biology experience is required. Interested candidates should send a CV, a brief research statement, and 2–3 references to kaychoi@iu.edu.
My paper on nucleotide exchange in RFC is now available at PNAS! www.pnas.org/doi/10.1073/...
Should you read if you already read our preprint? Yes!
Two big updates made during peer-review include:
Should you read if you already read our preprint? Yes!
Two big updates made during peer-review include:
PNAS
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans...
www.pnas.org
November 13, 2025 at 7:13 PM
My paper on nucleotide exchange in RFC is now available at PNAS! www.pnas.org/doi/10.1073/...
Should you read if you already read our preprint? Yes!
Two big updates made during peer-review include:
Should you read if you already read our preprint? Yes!
Two big updates made during peer-review include:
Reposted by Joshua Pajak
There are 3 PhD positions available in my lab using cryoEM to investigate phage structure!
- SWBio DTP: tinyurl.com/ytdft9bj, to apply: www.swbio.ac.uk/programme/ho...
- LSI and CSC PhD studentships and how to apply: tinyurl.com/45dze6se
- SWBio DTP: tinyurl.com/ytdft9bj, to apply: www.swbio.ac.uk/programme/ho...
- LSI and CSC PhD studentships and how to apply: tinyurl.com/45dze6se
November 12, 2025 at 12:39 PM
There are 3 PhD positions available in my lab using cryoEM to investigate phage structure!
- SWBio DTP: tinyurl.com/ytdft9bj, to apply: www.swbio.ac.uk/programme/ho...
- LSI and CSC PhD studentships and how to apply: tinyurl.com/45dze6se
- SWBio DTP: tinyurl.com/ytdft9bj, to apply: www.swbio.ac.uk/programme/ho...
- LSI and CSC PhD studentships and how to apply: tinyurl.com/45dze6se
Reposted by Joshua Pajak
On a gruelling hunt for rare associated molecules in your #cryoEM particle stack and not sure where to look?
Discover practical tips and tricks in our new case study using #CryoSPARC v4.7.1 where we find and refine a low-population interaction partner!
guide.cryosparc.com/processing-d...
Discover practical tips and tricks in our new case study using #CryoSPARC v4.7.1 where we find and refine a low-population interaction partner!
guide.cryosparc.com/processing-d...
October 30, 2025 at 1:33 PM
On a gruelling hunt for rare associated molecules in your #cryoEM particle stack and not sure where to look?
Discover practical tips and tricks in our new case study using #CryoSPARC v4.7.1 where we find and refine a low-population interaction partner!
guide.cryosparc.com/processing-d...
Discover practical tips and tricks in our new case study using #CryoSPARC v4.7.1 where we find and refine a low-population interaction partner!
guide.cryosparc.com/processing-d...
Reposted by Joshua Pajak
Great collaboration with @guo-lab.bsky.social to determine an in situ architectural model of the Tad pilus machine. Be on the lookout soon for a preprint on the same topic by Grant Jensen and @viollierpat.bsky.social. #microsky
November 6, 2025 at 3:51 PM
Great collaboration with @guo-lab.bsky.social to determine an in situ architectural model of the Tad pilus machine. Be on the lookout soon for a preprint on the same topic by Grant Jensen and @viollierpat.bsky.social. #microsky
Reposted by Joshua Pajak
Excited to share our latest @nature.com: How does naloxone (Narcan) stop an opioid overdose? We determined the first GDP-bound μ-opioid receptor–G protein structures and found naloxone traps a novel "latent” state, preventing GDP release and G protein activation.💊🧪 🧵👇 www.nature.com/articles/s41...
November 5, 2025 at 4:23 PM
Excited to share our latest @nature.com: How does naloxone (Narcan) stop an opioid overdose? We determined the first GDP-bound μ-opioid receptor–G protein structures and found naloxone traps a novel "latent” state, preventing GDP release and G protein activation.💊🧪 🧵👇 www.nature.com/articles/s41...
Reposted by Joshua Pajak
Next week LinkedIn will use your personal data for AI training by automatically enabling permissions.
To manually turn off go to:
Settings ➡️ Data Privacy ➡️ under
“How LinkedIn uses your data” click “Data for Generative AI improvement” ➡️ toggle off
To manually turn off go to:
Settings ➡️ Data Privacy ➡️ under
“How LinkedIn uses your data” click “Data for Generative AI improvement” ➡️ toggle off
November 2, 2025 at 5:07 AM
Next week LinkedIn will use your personal data for AI training by automatically enabling permissions.
To manually turn off go to:
Settings ➡️ Data Privacy ➡️ under
“How LinkedIn uses your data” click “Data for Generative AI improvement” ➡️ toggle off
To manually turn off go to:
Settings ➡️ Data Privacy ➡️ under
“How LinkedIn uses your data” click “Data for Generative AI improvement” ➡️ toggle off
Reposted by Joshua Pajak
JD Vance claims that diversity weakens unions, as people end up distrusting each other and not organizing.
Let me tell you two menswear stories related to this claim. 🧵
Let me tell you two menswear stories related to this claim. 🧵
October 30, 2025 at 8:07 AM
JD Vance claims that diversity weakens unions, as people end up distrusting each other and not organizing.
Let me tell you two menswear stories related to this claim. 🧵
Let me tell you two menswear stories related to this claim. 🧵
Reposted by Joshua Pajak
Our paper in Science is out! @souravagrawal.bsky.social, @rlynn.bsky.social, @susvirkar.bsky.social, and the rest of the team show human RPA is a telomerase processivity factor essential for telomere maintenance. This reshapes our thinking about telomerase regulation. www.science.org/doi/10.1126/...
Human RPA is an essential telomerase processivity factor for maintaining telomeres
Telomerase counteracts telomere shortening by repeatedly adding DNA repeats to chromosome ends. We identified the replication protein A (RPA) heterotrimer as a telomerase processivity factor critical ...
www.science.org
October 30, 2025 at 10:07 PM
Our paper in Science is out! @souravagrawal.bsky.social, @rlynn.bsky.social, @susvirkar.bsky.social, and the rest of the team show human RPA is a telomerase processivity factor essential for telomere maintenance. This reshapes our thinking about telomerase regulation. www.science.org/doi/10.1126/...
Reposted by Joshua Pajak
Happy to share a new publication on Mechanistic Coupling of Enzyme Activities at the Replisome in JBC. We #Traklab compare and contrast strategies used across organisms to coordinate the many enzymatic processes that occur during DNA replication. Hope it is helpful. doi.org/10.1016/j.jb...
October 24, 2025 at 6:12 PM
Happy to share a new publication on Mechanistic Coupling of Enzyme Activities at the Replisome in JBC. We #Traklab compare and contrast strategies used across organisms to coordinate the many enzymatic processes that occur during DNA replication. Hope it is helpful. doi.org/10.1016/j.jb...
Reposted by Joshua Pajak
Visualizing influenza A virus assembly by in situ cryo-electron tomography
www.nature.com/articles/s41...
www.nature.com/articles/s41...
Visualizing influenza A virus assembly by in situ cryo-electron tomography - Nature Communications
Influenza A virus must package eight separate genomic segments, called viral ribonucleoproteins (vRNPs). Using in situ cryo-electron tomography, the authors visualize how vRNPs are clustered on cell m...
www.nature.com
October 23, 2025 at 2:01 PM
Visualizing influenza A virus assembly by in situ cryo-electron tomography
www.nature.com/articles/s41...
www.nature.com/articles/s41...
Reposted by Joshua Pajak
New preprint from the lab for any DNA repair or replication stress geeks out there!
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
A nuclease-driven mechanism of post-replicative ssDNA gap suppression.
The persistence of post-replicative ssDNA gaps following PRIMPOL-mediated replication repriming is linked to chemosensitivity, and in all models reported to date the nuclease MRE11 has been implicated...
www.biorxiv.org
October 22, 2025 at 6:56 PM
New preprint from the lab for any DNA repair or replication stress geeks out there!
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
Reposted by Joshua Pajak
Vanderbilt has arrived, late to the chat, with this shambles of a response. While technically true, this is a clear abdication of any moral responsibility. They even work in a mention of their commitment to "institutional neutrality" later in the email.
October 20, 2025 at 9:26 PM
Vanderbilt has arrived, late to the chat, with this shambles of a response. While technically true, this is a clear abdication of any moral responsibility. They even work in a mention of their commitment to "institutional neutrality" later in the email.
Very sad to read about Daniel Narodistky’s passing, I’ve spent countless joy hours learning chess from his videos.
October 21, 2025 at 1:27 AM
Very sad to read about Daniel Narodistky’s passing, I’ve spent countless joy hours learning chess from his videos.
What a grand slam!! The vibes in Seattle are immaculate, I can feel it all the way across the country. Gotta love baseball
October 18, 2025 at 1:03 AM
What a grand slam!! The vibes in Seattle are immaculate, I can feel it all the way across the country. Gotta love baseball
Reposted by Joshua Pajak
Have you ever looked at the night sky and wondered if there’s a chlorophyll f in the reaction centre of Photosystem I from far-red light adapted cyanobacteria? 🦠
Well, we did (don’t judge) and the work that followed is now out as a First Release in @science.org
www.science.org/doi/10.1126/...
Well, we did (don’t judge) and the work that followed is now out as a First Release in @science.org
www.science.org/doi/10.1126/...
Locating the missing chlorophylls f in far-red photosystem I
The discovery of chlorophyll f-containing photosystems, with their long-wavelength photochemistry, represented a distinct, low-energy paradigm for oxygenic photosynthesis. Structural studies on chloro...
www.science.org
October 11, 2025 at 10:37 AM
Have you ever looked at the night sky and wondered if there’s a chlorophyll f in the reaction centre of Photosystem I from far-red light adapted cyanobacteria? 🦠
Well, we did (don’t judge) and the work that followed is now out as a First Release in @science.org
www.science.org/doi/10.1126/...
Well, we did (don’t judge) and the work that followed is now out as a First Release in @science.org
www.science.org/doi/10.1126/...
One of the best parts of being an academic scientist is feeling really good about a grant you just wrote. No guarantees it’ll get funded, but there’s so many good ideas in there that I’m going to pursue regardless 😎
October 13, 2025 at 12:50 AM
One of the best parts of being an academic scientist is feeling really good about a grant you just wrote. No guarantees it’ll get funded, but there’s so many good ideas in there that I’m going to pursue regardless 😎
Reposted by Joshua Pajak
No words
May 30, 2025 at 12:23 PM
No words
Reposted by Joshua Pajak
Shared courtesy of my Penn History colleague, Ben Nathans
October 12, 2025 at 4:04 PM
Shared courtesy of my Penn History colleague, Ben Nathans
Reposted by Joshua Pajak
when UNC scored on the first possession of the first game and Colin Cowherd immediately posted this, and then UNC lost by 34
October 8, 2025 at 9:52 PM
when UNC scored on the first possession of the first game and Colin Cowherd immediately posted this, and then UNC lost by 34
Reposted by Joshua Pajak
🧐Checkout our preprint revealing the stepwise firing💥 mechanism of a Contractile Injection System @xujwet.bsky.social&@chipericson.bsky.social trapped the complex by structure-guided engineering🧪 in multiple intermediate states and imaged them by multimodal #cryoEM❄️🔬
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
October 8, 2025 at 9:18 PM
🧐Checkout our preprint revealing the stepwise firing💥 mechanism of a Contractile Injection System @xujwet.bsky.social&@chipericson.bsky.social trapped the complex by structure-guided engineering🧪 in multiple intermediate states and imaged them by multimodal #cryoEM❄️🔬
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
Reposted by Joshua Pajak
New method paper:
Bennie Lemmens et al @scilifelab.se describe 3D-SPARK, a super-resolution microscopy method that maps changes in DNA replication nanostructures in response to genetic perturbations or drugs, linking spatial cell biology with DNA synthesis dynamics
www.embopress.org/doi/full/10....
Bennie Lemmens et al @scilifelab.se describe 3D-SPARK, a super-resolution microscopy method that maps changes in DNA replication nanostructures in response to genetic perturbations or drugs, linking spatial cell biology with DNA synthesis dynamics
www.embopress.org/doi/full/10....
October 7, 2025 at 1:04 PM
New method paper:
Bennie Lemmens et al @scilifelab.se describe 3D-SPARK, a super-resolution microscopy method that maps changes in DNA replication nanostructures in response to genetic perturbations or drugs, linking spatial cell biology with DNA synthesis dynamics
www.embopress.org/doi/full/10....
Bennie Lemmens et al @scilifelab.se describe 3D-SPARK, a super-resolution microscopy method that maps changes in DNA replication nanostructures in response to genetic perturbations or drugs, linking spatial cell biology with DNA synthesis dynamics
www.embopress.org/doi/full/10....
Reposted by Joshua Pajak
Out in Science Advances: Our #cryoEM structure of HFTV1, a virus infecting the halophile #archaea. *First full atomic structure (containing all structural proteins) of any tailed virus!* Congrats and thanks to all co-authors and our fantastic collaborators! www.science.org/doi/10.1126/...
Cryo-EM resolves the structure of the archaeal dsDNA virus HFTV1 from head to tail
This structure of an archaeal tailed virus (arTV) provides detailed insights into arTV assembly and infection mechanisms.
www.science.org
October 6, 2025 at 11:31 AM
Out in Science Advances: Our #cryoEM structure of HFTV1, a virus infecting the halophile #archaea. *First full atomic structure (containing all structural proteins) of any tailed virus!* Congrats and thanks to all co-authors and our fantastic collaborators! www.science.org/doi/10.1126/...
I for one was never really into working at coffee shops, but this week I've been writing in a Dunkin' near my mechanic and have been really productive. Must be some Massachusetts finally making its way into my blood.
September 25, 2025 at 12:22 PM
I for one was never really into working at coffee shops, but this week I've been writing in a Dunkin' near my mechanic and have been really productive. Must be some Massachusetts finally making its way into my blood.
Reposted by Joshua Pajak
STRUCTURE OF A NITROGENASE-PII SUPERCOMPLEX
New work from the oxidoreductase half of the group.
www.biorxiv.org/content/10.1...
New work from the oxidoreductase half of the group.
www.biorxiv.org/content/10.1...
September 11, 2025 at 4:53 PM
STRUCTURE OF A NITROGENASE-PII SUPERCOMPLEX
New work from the oxidoreductase half of the group.
www.biorxiv.org/content/10.1...
New work from the oxidoreductase half of the group.
www.biorxiv.org/content/10.1...