The code for GPCR regulation

Work done in the lab of Prof. Arun K. Shukla at GPCR Biology Lab, BSBE department, IIT Kanpur.

About author

Jagannath Maharana is a PhD scholar in GPCR biology lab, IIT Kanpur, India. Jagannath’s primary focus is on studying the structural aspects of GPCR and GPCR-transducer complexes using Cryo-EM and many other complementary approaches. Jagannath, born in a small village in the state of Odisha, did his schooling from his hometown and pursued his bachelor’s from Regional Institute of Education, Bhubaneswar and master’s degree from Banaras Hindu University, where he graduated with a gold medal. His dream and passion led him to IIT Kanpur, for pursuing his career in research. Working in the GPCR lab, Jagannath has contributed immensely in many major projects. He has been a key contributor to the structural biology team of the lab. His working philosophy is to work and grow together as a cohesive team. In his free time, he likes to sketch and draw to communicate the ongoing research findings with the broader audience.

Interview

How would you explain your research outcomes to the non-scientific community?

I used to wonder as a child how taking such small pills could cure diseases. With time, as I learned more about proteins and the complexity of human physiology, it made me ponder even more how one protein can interact with hundreds of partners to perform diverse functions. Working in Arun’s lab as a doctoral student, we focus on cell surface proteins called G protein-coupled receptors (GPCRs), which receive molecules from the outer environment and pass the message inside the cells eventually leading to various crucial cellular responses. This cellular signaling ought to be regulated to prevent adverse effects on the wellbeing of a cell, and to the rescue there are another class of proteins known as beta-arrestins acting as master regulators of GPCR signaling. However, the question remains open how only two kinds of beta-arrestin could recognize a thousand kinds of GPCRs. We set out on a quest to answer this puzzle in this study. Here, we used cryogenic electron microscopy (cryo-EM), an advanced microscopy technique that enables visualizing proteins in solution and determining their atomic structure. Solving multiple structures of GPCR-arrestin complexes led to the discovery of a conserved pattern required for beta-arrestin interaction with GPCRs. Surprisingly, this pattern was also found to be present in a wide range of receptors. Through structural evidence combined with cellular experiments, we have revealed the “key” secrets behind two proteins regulating hundreds of receptors. Now I know to which proteins medicines bind and how these proteins are kept in check.

A. There are nearly a thousand GPCRs which are regulated by only two kinds of beta-arrestins. A GPCR master key opens up the locks on beta-arrestins to activate and subsequent functional outcomes. B. A hand-painted illustration by Jagannath to depict the discovered pattern: P-X-P-P for beta-arrestin activation. Only the appropriate combination opens up the "cryptex", revealing the secrets of GPCR-mediated beta-arrestin functions.

How do these findings contribute to your research area?

We have undoubtedly unveiled some interesting aspects of GPCR signaling and taken a step further towards answering a few long-standing questions in the field. After a decade of the first available active structure of beta-arrestin1, we have now delivered the first fully activated conformation of the other isoform, beta-arrestin2, which is equally potent. In addition, we have also provided the structural basis for the activation mechanism of beta-arrestins driven by three different GPCRs, which was previously limited to one. Our structures allow researchers to witness the existence of the universal mechanism we have discovered.

“After a decade of the first available active structure of beta-arrestin1, we have now delivered the first fully activated conformation of the other isoform, beta-arrestin2, which is equally potent. “

What was the exciting moment during your research?

There have been many bottlenecks during the pursuit of this research. Nevertheless, when years of hard work pays off, one can never forget that day. I can point out one incident that I like the most: the day when we cracked our first structure for this project. After consistent efforts for several years, we solved the structure of beta-arrestin2 to the highest resolution recorded for any cryo-EM structure of these protein complexes. Arun was the happiest, and the pride he carried in his eyes truly made my day.

What do you hope to do next?

Cracking the beta-arrestin2 active structure, which seemed near impossible initially, has instilled confidence in me to work on challenging topics going forward. I would like to visualize the complex machinery of protein workhorses inside our cells.

Where do you seek scientific inspiration from?

My major day-to-day source of inspiration is my mentor, Prof. Arun K. Shukla. His dedication to science and his continuous motivation have helped me shape into an astute researcher. I have been learning from him how to think and approach a scientific problem. His “play-to-win” and “never-give-up” attitude is what makes us push ourselves and try harder to achieve our goals.

How do you intend to help Indian science improve?

I think the young generation is our future, and we have to change the imposter mindset about pursuing a research career in India. I’d like to give a message to the undergrads in their masters and bachelors who aspire to be researchers one day: “Dream big and keep your dreams alive”. I have seen it come true. Dr. Ramanuj Banerjee, one of the post-doctoral fellows in our lab, says, “If the researchers overseas can do it, then we can do it too”.

Reference

Maharana J, Sarma P, Yadav MK, Saha S, Singh V, Saha S, Chami M, Banerjee R and Shukla AK. Structural snapshots uncover a key phosphorylation motif in GPCRs driving β-arrestin activation. Molecular Cell, 2023, https://www.cell.com/molecular-cell/pdfExtended/S1097-2765(23)00320-9

Copy Editor

Pragya Gupta

PhD Scholar, University of Melbourne, Australia

Beside being a passionate stem cell researcher, Pragya Gupta is trained in Indian classical music, enjoys baking, inventive craftwork and learning about different cultures. She is currently doing her PhD at the University of Melbourne in Australia, where she is researching new ways to treat brain cancers.

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