A group photo of Ian with some of his friends from the 20th Floor Molecular Medicine. Everyone but Ian is wearing a tee shirts with a picture of Ian on it.

Congratulations on a great PhD defense @ianyyen.bsky.social!
I've enjoyed discussing the finer points of cryo-EM with Ian, being on his advisory committee, and having him as an "honorary group member" these past 6 years.

Thank you so much @johnrubinstein.bsky.social for all the support these past few years!

Our work with the Brun lab on the in situ architecture of the Caulobacter crescentus Tad pilus machine is published in mBio. Amazing collaborative effort led by James Iarocci @jamesiarocci.bsky.social

New paper alert! Outstanding work by PhD candidate Nathan Roberge, great collab with the Ellison and Maxwell labs. #Pseudomonas #phage DMS3 encodes Aqs1, an inhibitor of #T4P assembly ATPase PilB, but how it binds and leads to loss of function was unknown. @mcmasteriidr.bsky.social

🧵 Proud to present a tour de force by postdoc @gregbwhitfield.bsky.social solving the mystery of how bacterial Tad pili can extend and retract with a single motor ATPase. Great collaboration with Lynne Howell, @dr-lori-burrows.bsky.social, @ianyyen.bsky.social www.biorxiv.org/content/10.6...

Just got word that we are a go for the Bacterial Cell Biology and Development GRS and GRC at Southern New Hampshire University!

GRS will be on June 5-6, 2027

GRC will be from June 6-11, 2027

Block off your calendars Prokaryotic Cell Biologists!

More details to come! Please repost!

Structure-guided design of a synthetic bile acid that inhibits Clostridioides difficile TcdB toxin - Nature Microbiology A bile acid-bound structure of toxin TcdB revealed the mechanism of inhibition and guided the design of a synthetic bile acid that alleviated Clostridioides difficile infection in mice.

#NewResearch

A bile acid-bound structure of toxin TcdB revealed the mechanism of inhibition and guided the design of a synthetic bile acid that alleviated C. difficile infection in mice.

#MicroSky 🦠💊

www.nature.com/articles/s41...

Great collaboration with @brunlabcaulo.bsky.social for resolving the Tad pilus machine structure by cryo-ET. Beautiful work by graduate students James Iarocci and Ryu Williston in our lab.

Preprint:www.biorxiv.org/content/10.1101/2025.11....

Twitching motility suppressors reveal a role for FimX in type IV pilus extension dynamics Author summary Type IV pili enable Pseudomonas aeruginosa to attach to surfaces, move (twitch), and form biofilms. Pilus extension is powered by the motor protein PilB, which is regulated by other fac...

New paper alert! We used our fav technique, genetic suppression, to understand how FimX controls function of the T4P PilB motor ATPase in Pseudomonas aeruginosa. Great collab with the Ellison lab at U Georgia who helped with some fancy microscopy to capture pilus dynamics! doi.org/10.1371/jour...

Separation of Pseudomonas aeruginosa type IV pilus-dependent twitching motility and surface-sensing responses | mBio The ability of bacteria to sense and respond to contact with surfaces is important for triggering changes in secondary messenger levels and gene expression, leading to the formation of biofilms and in...

New paper! Specific PilA and PilY1 sequences make PilU dispensable for T4P-dependent twitching motility in P. aeruginosa. However, most suppressors still had high cAMP levels from loss of PilU, showing that motility and surface sensing responses can be uncoupled.🧐 ⏩ journals.asm.org/doi/10.1128/...

An infographic showing how smog impacts the human body.

Breathing polluted air increases the risk of #osteoporosis, growing evidence shows.

Learn more: scim.ag/4lUQBrf #ScienceMagArchives

When particles have orientation bias, the resulting maps are often streaked along the missing directions. In this case study, we cover why orientation bias produces anisotropic #cryoEM maps and how you may be able to recover from it!

guide.cryosparc.com/processing-d...

Twitching motility suppressors reveal a role for FimX in type IV pilus extension dynamics In Pseudomonas aeruginosa, retractable protein filaments called type IV pili (T4P) facilitate surface adherence, sensing, and directional movement known as twitching motility. T4P are necessary for th...

New paper alert! PhD candidate Nathan Roberge is studying regulation of the #T4P assembly ATPase PilB and identified suppressors of FimX with enhanced motility. Where did they map? Find out here: www.biorxiv.org/content/10.1...

Fantastic collaboration with @ckellison.bsky.social where we demonstrate functional divergence of FimX to regulate type IV pilus positioning along the long axis of Acinetobacter baylyi

ChimeraX daily builds can predict small complexes of proteins, nucleic acids and small molecules using Boltz on your Mac, Windows or Linux computer without Nvidia graphics. www.rbvi.ucsf.edu/chimerax/dat...

Bidirectional pilus processing in the Tad pilus system motor CpaF - Nature Communications The ATPase CpaF from C. crescentus powers pilus dynamics in the bacterial Tad pilus system. Cryo-EM and light microscopy characterisation of CpaF uncovers a mechanism for how CpaF may drive both pilus...

We encourage you to also check out an alternative model of how CpaF assembles the Tad pilus proposed by @lowlab.bsky.social published a few months ago in the same journal.
www.nature.com/articles/s41...

Many thanks to everyone involved for their contribution, mentorship, and support - Greg Whitfield, @johnrubinstein.bsky.social, @dr-lori-burrows.bsky.social, @brunlabcaulo.bsky.social, and my PI Lynne Howell! We're grateful to the reviewers for enabling a smooth review process.

Conformational changes in the motor ATPase CpaF facilitate a rotary mechanism of Tad pilus assembly - Nature Communications The bacterial Tad pilus extends and retracts using a single bifunctional ATPase CpaF. Here, the authors employ cryo-EM, fluorescent microscopy, and AlphaFold modelling to propose how a rotary mechanis...

Thrilled to announce my first PhD publication in Nature Comms! We determined structures of the Tad pilus ATPase CpaF from Caulobacter. We use these structures to propose how CpaF employs a rotary mechanism of catalysis to drive Tad pilus assembly.
www.nature.com/articles/s41...

Image processing for cryo-electron microscopy Cryo electron microscopy (cryo EM) is a major structural biology method for studying macromolecular complexes and cellular structures in their native states. Stable high resolution cryo microscopes, …

Learn principles of image processing to determine macromolecular structures by #cryoEM: Sign up for EMBO Practical Course on Image processing for cryo-electron microscopy in London, UK, 9–16 September

Deadline: 25 April

meetings.embo.org/event/25-cry...
#EMBOcryoEM #EMBOevents 🧪

Stimulation of the Caulobacter crescentus surface sensing pathway by deletion of a specialized minor pilin-like gene Bacteria colonize surfaces through complex mechanisms of surface sensing. Pili are dynamic bacterial appendages that play an important role in this process. In Caulobacter crescentus , tension on retr...

1/10 🧵 Injecting some science in your feed: Happy to share another chapter in our investigation of bacterial surface sensing. We describe the role of CpaL, a minor pilin-like protein, a key player in surface sensing and adhesion in Caulobacter crescentus. #microsky www.biorxiv.org/content/10.1...