Ahmad Jomaa

@jomaalab.bsky.social

Assistant Professor at the University of Virginia, Biochemist, Molecular and Structural Biologist, Husband, Father, Traveller #cryoem #ribosome #rna med.virginia.edu/jomaa-lab/

Happy to share the latest work from the lab, led by @mudgal17.bsky.social‬, in collaboration with the Weis lab @ethzurich.bsky.social. How do nuclear membranes fuse during NPC assembly? We answer this question in our latest work, where we identify a new mechanism for membrane fusion… (1/13)

bioRxiv Cell Biology@biorxiv-cellbio.bsky.social · last yr.

A conserved mechanism of membrane fusion in nuclear pore complex assembly https://www.biorxiv.org/content/10.1101/2025.07.21.665908v1

1/11 New preprint from the Sternberg lab in collaboration with the Fernández lab! We are excited to share our structure-function study of DRT10, a bacterial defense-associated reverse transcriptase that synthesizes long tandem-repeat DNA.🧵 Read the full story here: www.biorxiv.org/content/10.6...

Mechanism of tandem-repeat DNA synthesis by an antiviral reverse transcriptase

Defense-associated reverse transcriptases (DRTs) employ DNA synthesis to protect bacteria against phage infection[1][1],[2][2]. We previously showed that DRT10, a tripartite system comprising an RT, a...

biorxiv.org

Cryo-ET is often framed as a tool for in situ protein structure. But what if the real revolution is contextualization? I explore how #teamtomo is redefining what "local" means in organelle biology, revealing membrane states rather than just protein structures. tinyurl.com/localmembrane

Think globally, act locally: Redefining organellar membrane environments through cryo-electron tomography

Early enthusiasm for the “cellular revolution” in cryo-electron tomography (cryo-ET) was largely driven by the promise of resolving protein structures…

sciencedirect.com

Disrupting phage liquid crystalline droplets restores antibiotic susceptibility in Pseudomonas aeruginosa biofilms out in @plosbiology.org by @abultarafder.bsky.social and team. Exciting collaboration with @geiselbiofilm.bsky.social @pearce-maths.bsky.social and others

PLOS Biology@plosbiology.org · 2mo ago

#Biofilm matrices containing filamentous phages help #Pseudomonas aeruginosa tolerate antibiotics. @abultarafder.bsky.social @tbharat-lab.bsky.social &co show that #nanobody disruption of #phage Pf4 #LiquidCrystalline droplets restores #antibiotic susceptibility @plosbiology.org 🧪 plos.io/4xkd6Mw

Top: Nanobody binders are potent inhibitors of Pf4 liquid crystalline droplet formation and disrupt preformed droplets. Cryo-ET of Pf4 liquid crystalline droplets incubated with Nb43. Tomographic slice of a Pf4 liquid crystalline droplet specimen incubated with (left) 0.1 μM and (right) 1 μM Nb43. Bottom: Schematic representation of nanobody action in abolishing antibiotic tolerance of P. aeruginosa biofilms. In untreated biofilms (left), cells show increased antibiotic tolerance due to Pf4 liquid crystalline droplets formed by depletion attraction in the biofilm EPS matrix, where encapsulated cells are protected by an antibiotic diffusion block. In nanobody treated biofilms, patchy binding of nanobody to Pf4 filaments reduces depletion attraction between the filaments preventing liquid crystalline droplet formation and encapsulation of cells, leading to increased antibiotic susceptibility of bacteria within the biofilm.

Measles is coming back. Until now, we didn't know how human antibodies actually recognize and neutralize the virus. No structure of either measles surface protein bound to a human antibody had ever been reported. We set out to change that.

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Oxygen gradients reshape cross-feeding through emergent spatial organization of gut commensal bacteria www.biorxiv.org/content/10.6... Use of isotope labels and cryo-CLEM-FIB-SIMS to study microbial communities by Hannah Ochner. Collaboration with @kiranrpatil.bsky.social @jmghigolab.bsky.social

Oxygen gradients reshape cross-feeding through emergent spatial organization of gut commensal bacteria

Microbial interactions unfold within environments structured by physical transport and chemical gradients. Yet most mechanistic studies rely on well-mixed systems that mask the reciprocal influences of environmental heterogeneity on metabolism and ecology. Here, we investigate how the physical environment modulates the interaction between the gut commensal Bacteroides thetaiotaomicron and Escherichia coli . In anoxic liquid culture, cell-resolved isotope imaging and genetic perturbations reveal exploitative cross-feeding, where E. coli consumes diffusible sugars released by B . thetaiotaomicron during starch degradation. When exposed to intestinal-like oxygen gradients in microfluidics, the interaction is restructured by spatial organization. The species self-organize into complementary niches: E. coli locally depletes sugars and oxygen, thereby expanding the anoxic niche required by B. thetaiotaomicron . A reactive transport model confirms that this organization arises from coupled feedback between physical transport and metabolic reaction rates. Together, our results reveal how physical structure and chemical gradients convert an exploitative cross-feeding interaction into a dynamic niche-construction process that generates emergent spatial organization and stabilizes coexistence. ### Competing Interest Statement The authors have declared no competing interest.

biorxiv.org

The early release version of our #cryoEM work on CDK11-cyclin L-SAP30BP has now been published at Nature Communications: www.nature.com/articles/s41... We got very helpful comments from the reviewers and added more structural analysis and biochemistry to support our conclusions. Please have a look!

Cryo-EM structures of the CDK11-cyclin L-SAP30BP complex reveal mechanisms of CDK11 regulation - Nature Communications

McGeoch and co-authors use cryogenic electron microscopy and biochemistry to determine the structure of the CDK11-cyclin L-SAP30BP complex and elucidate the regulation of CDK11 by SAP30BP within the t...

nature.com

Basil Greber@bjgreber.bsky.social · 5mo ago

Have a look at our latest results on #CDK regulation, just posted as a pre-print! This study was spearheaded by PhD student Amy McGeoch. Amy has determined the #cryoEM structure of the CDK11-cyclin L-SAP30B complex, an important regulator of #spliceosome activation. www.biorxiv.org/content/10.6...

Depictions of the structure of CDK11-cyclin L-SAP30BP. Four cryo-EM densities are shown at the top, two molecules models at the bottom. CDK11 is green, cyclin L is purple, and SAP30BP is yellow.