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Reposted by Krishna Reddy

Chris Mulligan @chrismulligan.bsky.social · 17/12/2025

🚨My lab is hiring a postdoc!🚨 If you’re interested in working out the mechanism and physiological impact of bacterial lipid transport processes then please apply! Job advert is here: tinyurl.com/4swddfda Get in touch by email (c.mulligan@kent.ac.uk) for informal enquiries Please repost! Thanks!

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Krishna Reddy @krishnareddy.bsky.social · 16/12/2025

My lab is hiring a postdoc! We have many exciting projects on membrane transporters at the interface of protein structure-function, bioinformatics, directed evolution, and protein engineering. Applications considered on a rolling basis, so submit ASAP. Please share! jobs.usf.edu/hcmUI/Candid...

jobs.usf.edu

Postdoctoral Scholar Research

The Reddy Lab at the University of South Florida (USF) is seeking a Postdoctoral Researcher to join our multidisciplinary team studying the structure, mechanism, evolution, and engineering of membrane...

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Krishna Reddy @krishnareddy.bsky.social · 01/12/2025

Our department is recruiting a mid-career faculty member in cryo-EM - come be my colleague and lab neighbor! It's an exciting time for structural biology at USF, anchored by an incoming JEOL CRYOARM 300. Feel free to DM if you have any questions. Please share! www.nature.com/naturecareer...

nature.com

ASSOCIATE/FULL PROFESSOR - Open Rank-Structural Biology - Tampa, Florida job with University of South Florida | 12849234

Seeking candidates for a tenured or tenure-track position who use structural biology-based approaches and cryo-EM

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Krishna Reddy @krishnareddy.bsky.social · 21/10/2025

Really inspiring work, congrats!

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

So cool to have a spotlight on our work like this - honestly as good an alternative to reading the paper itself, which I probably shouldn't say...and also stay tuned for cool transporter evolution work from Sam 👀

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

14/14 If you’ve made it this far, I really appreciate it (and also go touch grass). My lab is pushing this work in new directions and incorporating more fun, interdisciplinary techniques to understand transporter structure-function mechanism in unique ways. If this sounds interesting, reach out!

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

13/14 Too many folks to thank: @olgabiophys.bsky.social for her guidance/patience, the brilliant trainees I was privileged to work with, the collegial/rigorous reviewers, the many people who generously advised, and frankly me for pushing this to the end when common sense often suggested otherwise.

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

11/14 This means ion coupling isn’t solely dictated by ion-binding residues, but from allosterically regulated packing - a structural “clutch” linking ion/substrate binding. We think this applies to ion-coupled transport and beyond - small, distant mutations can flip fundamental energy landscapes.

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

10/14 What changed? Our evolutionary analysis gave us an elegant answer. A central ‘coupling’ helix is responsible for cooperative ion/substrate binding, and two changes at the start and end of this helix can turn sodium coupling on/off. These residues control how rigidly the helices pack together.

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

9/14 Cryo-EM with precise sample conditions and processing gave us the clue: the intermediate ancestor could spontaneously access the high-affinity substrate-binding state required for transport, which sodium-coupled transporters can only reach with sodium.

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

8/14 To our surprise, an ‘intermediate’ ancestor during the transition from sodium to proton coupling still had sodium binding sites, could bind sodium, but no longer needed sodium energy for substrate binding and transport - an ion-independent, ‘uncoupled’ transporter. How?

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

7/14 Our ancestral membrane proteins had terrible yields, making purification/characterization a pain. We reinvented all the lab pipelines to make this project work. I like to call this the protein purification of Theseus. If you replace every step of a protocol, is it the same protocol? 🤔

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

6/14 Since loops and tails are poorly reconstructed, we had to stitch in some loops/tails from existing proteins for expression constructs, which @olgabiophys.bsky.social affectionately called “Frankensteins”…which of course makes me Dr. Frankenstein.

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

5/14 We borrowed a page from their playbook, using ancestral protein reconstruction. Essentially, we use phylogenetics to approximate how evolution might have occurred, and generate inferred ‘ancestral’ transporter sequences spanning this functional transition. Great review: doi.org/10.1146/annu...

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

4/14 For years, we did sequence alignments and mutated residues that looked interesting, to no avail. These processes might be too complex/allosteric - inspired by beautiful work from @joethorntonlab.bsky.social, we thought understanding the evolutionary process could be an avenue to untangle this.

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

3/14 Brain glutamate transporters use sodium to recycle neurotransmitters. Close relatives in bacteria also use sodium…but others use protons. We wanted to understand how transporters made this switch. What changes in sequence made this possible? And what molecular features enforce ion coupling?

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Krishna Reddy @krishnareddy.bsky.social · 12/09/2025

2/14 Secondary active transporters perform ‘concentrative’ transport, moving substrates against their concentration gradients by harnessing energy from ion gradients. Organisms have evolved their transporters based on their environment – i.e., halophiles often have sodium-driven transporters.

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Krishna Reddy @krishnareddy.bsky.social · 12/12/2024

Last chance to apply for the cryo-EM faculty position in my department at USF (Tampa, FL)! Open to all career stages, and we have a 300kV on its way. Submit by December 15 for priority consideration, and reach out with any questions. Please repost! #ttjobs bit.ly/USFFac-Struc... (ID 37774)

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