Interview with the 2023 Hooke medal winner Andrew Carter

Andrew Carter

Congratulations on winning the BSCB Hooke medal award. How do you feel about receiving this prize?

I'm very honoured to have been chosen. I'm really pleased that my lab's work on dynein has been recognised; I think it's a fascinating topic that is applicable to a lot of people in a lot of different fields. So, it is a real highlight. I would like to mention that I benefited a lot from my collaborators and colleagues during my postdoc and especially from the many people who have worked in my lab; I am very grateful to all of them and the ideas they have generated.

How did you first become interested in science?

My parents were both lecturers, and in particular for my mother (who was a leech neurobiologist), her office was also her lab. So, half of it was a desk full of papers and the other half was microscopes, electrophysiology equipment and all sorts of cool stuff. I used to really like going into work with her; I remember dissecting her spider plants under the light microscope a lot, and it was always fun to be in that environment. I also remember my parents always talking about science at the breakfast table; I didn't usually understand what they were discussing, but when I started studying it more at school, science became something I was able to easily become interested in. I also had some very enthusiastic teachers at school and they made science fun, maybe even a little bit dangerous and exciting.

I understand you discovered your love for structural biology during your undergraduate at the University of Oxford – were there any particular discoveries or scientists that inspired you?

At that time [during my undergraduate], there were a number of [protein] structures coming out. And back then, we still had paper journals, rather than online. So, you'd see the front cover of the journal, and there would be the structure of a protein you'd learned about previously and suddenly seeing it on the front page was very exciting. The one that really stands out to me was KcsA, the potassium channel described by Rob MacKinnon, because we had done a whole course on how it selects ions, going all the way back to work by Hodgkin and Huxley and working out that there must be a selectivity filter. And then, using molecular cloning, people had worked out that there were tyrosine residues involved and models were proposed. But suddenly, once the structure was resolved, it explained everything and made it clear that some of the previous models were wrong and it kind of ‘fixed’ it all; I thought that was very elegant and exciting, the way that the structures could explain all these aspects which had previously been slightly murky.

I was also inspired by some of the great lecturers at Oxford University. I should mention Professor Louise Johnson, who was very interesting in terms of her work on phosphorylases and various enzymes that we studied. She gave her lectures in a very calm and beautifully clear way, and she had a very interesting life story that we were all fascinated by; she'd been involved with solving the structure of one of the very first enzymes to be discovered, lysozyme. But despite my interest in structural biology, I wondered whether I would have the skills to pursue it, as the course introduction to crystallography was quite mathematical. But then a friend of mine did his 4th year project with David Barford, who is now one of the heads of division here, and this made it clear to me that actually, it was something I could do.

Did you consider working in any fields other than structural biology?

Yes, I was very tempted to become a fly neurobiologist. I did some summer projects with Andrea Brand at the Gurdon Institute, who developed the GAL4 enhancer trap system. I was fascinated by neurobiology and I've still got some pictures on my wall of neurons growing out within the fly larva. So, it was a difficult decision between going down that route or crystallography.

In 2003 you made the big move to Ron Vale's lab over in San Francisco for a postdoc – what prompted this trans-Atlantic move and how did you find the change?

My PhD advisor, Venki Ramakrishnan, had moved from the University of Utah in the USA just before I joined his group at the LMB in Cambridge. I can't remember if it was his suggestion, but somehow, I knew that America was a good place to go and do a postdoc. So, I looked at a few different labs there, and Ron Vale was one of the ones I contacted, because I had met Ron when I was an undergraduate. I did my final year project at Oxford on kinesin motors and somebody told me about this open discussion meeting at the Royal Society; you could just turn up and it turned out all of the kinesin researchers were there. When I was there, Ron was really generous with his time and spent about half an hour talking to me about recent advances from his lab. And that really struck me, so I contacted him and visited his lab, which had a really good vibe and seemed very friendly. Also, you mentioned the ‘big move’, and while it was very daunting beforehand, once I got there, it was fine, in part because the environment in the lab was very welcoming. There was this amazing mix of biochemists, structural biologists, cell biologists, lots of light microscopists and some physicists as well. There was this very broad range of topics and lots of different projects, and so there was plenty of help and lots of ideas from different perspectives, and that was a really wonderful environment to be in.

Would you say that team building and having that rapport is important in building an effective lab environment?

Absolutely. One thing my lab does, which was inspired by Ron, is a lab retreat. Each year Ron used to take us to various amazing places in California, the wine country, the Big Sur coast or several times we went to Tahoe and combined science with some skiing. We would usually rent a house and take sleeping bags. Everyone pitched in with cooking and someone in the lab was usually a fantastic cook; you could tell who because they would bring along their own cooking implements and take control of the kitchen. The thing that struck me about those retreats were how many ideas they generated and how many new projects in the lab came out of the presentations that everyone did. And so, soon after starting my lab, we started doing the same. Actually, we take over my parent’s house for a couple of days, borrow the dogs, go for some hikes and talk science. It's good because it's more informal and it brings ideas up that you wouldn't think of in regular lab meeting format.

You started your own group in 2010 back at the MRC LMB – what made you decide to return there and how did you find the transition to group leader?

At that time, we had a first view of how the dynein motor worked, and I knew I wanted to work towards the next stages of understanding dynein, which seemed pretty challenging, because it was all crystallography still at that stage. Also, I wanted to focus more on the cell biology questions, such as how dynein finds its cargo. The LMB seemed to be a really good place to do this because it has amazing facilities, including crystallography and light microscopy [this was all before cryo-electron microscopy (cryoEM)!]. But importantly, there is also this culture of helping others and sharing reagents and advice, which is something I valued as a PhD student here. I also really enjoyed the fact there were a group of us who started our labs at a similar time. Having a group of peers, who are going through similar challenges and that support and encourage each other was really helpful.

One of the discoveries your lab made was resolving the structural interactions of the adaptor protein BICD2 with dynein and dynactin – what would you say were the most fascinating or surprising findings you made?

I want to step back a bit, because the whole BICD2 story really launched us into studying dynein–cargo interactions, but it wasn't clear how we were going to do it. At this point, we knew that single yeast dyneins could walk in a processive manner over long distances, and we also knew that mammalian dynein didn't. If you put it on beads it could move, but on its own, it didn't. So, a number of us in the field wondered why that would be. Then, there was a paper by the Akhmanova and Hoogenraad labs, which showed that this protein, BICD2, helped dynein and dynactin interact. In sucrose gradients, they wouldn't really interact very well, but when you added this protein, they came together. I had a postdoc, Max Schlager, who came from a cell biology background, and he knew about this work, and so he suggested that maybe BICD2 activates the dynein and makes it walk. He got together with a student from my colleague Simon Bullock's lab, and they did some single-molecule studies and showed that dynein needed BICD2 and dynactin to move long distances. That was a very exciting discovery, because it changed our view of how dynein and dynactin work. We'd always thought that dynactin was an adapter that was flexibly coupled to dynein and links it to cargo. So, it was a very surprising finding that these weren't two separate complexes, but intrinsically the motor function is a dynein–dynactin machine rather than just dynein on its own. We also never guessed there would be two dyneins per dynactin, which doubles the force. I love the way that solving a new structure gives us new insights into things that you just wouldn't have guessed.

More recently, you have focused on dynein in cilia, where you describe a new protein, Shulin, and its role in the axonemal outer dynein arms (ODAs). How did this project come about?

I worked on Tetrahymena ODAs, which are what power the beating of cilia, right at the beginning of my postdoc; I spent 6 months purifying and trying to crystalize them. Many years later, [the] Wellcome [Trust] asked me to do an Open Day at the Diamond Light Source, and I needed something for people to look at under the microscope. So, I bought some Tetrahymena and we had the live microscope images up on a TV screen and it worked really well. This led me to read more into Tetrahymena, and people had made good advances in terms of modifying the genome. In particular, Kazufumi Mochizuki had made a whole set of plasmids, which he very kindly sent me. Then, a summer student and I established a protocol in the lab for generating genetically tagged Tetrahymena, which turned out to be cool, because you have to use a biolistic gold bead gun to shoot them with your DNA constructs, and then select for incorporation with antibiotics for a month. We used this to tag ODAs.

Then Girish Mali, a first author (one of three) of the study, approached me about doing a postdoc because he was really interested in the assembly of dyneins, and so he came and did some work on ODA assembly factors. However, as a side project, we thought we'd try pulling out newly synthesized ODAs from the cell body to see if there was anything different about them compared to the ODAs found in the cilia. One of the reasons for doing that was at a conference many years earlier, Steve King, who has worked on axonemal dyneins his entire career, said “there must be something different about axonemal dynein when it's in the cytoplasm, because it doesn't move”. And Girish identified this protein, Shulin, which binds to cytoplasmic ODAs, and did some beautiful functional assays and cryoEM to show that it inhibits dynein movement. He also showed that this inhibition was really important for delivering those newly synthesized ODAs to their final location in the cilia. He had help with the cryo-EM from his co-authors, but Girish did a brilliant job of taking that initial ‘here is a completely new protein’ and working out what it did in the cell.

It's exciting that you got to name a new protein, too; where did the name Shulin come from?

Girish and one of his friends came up with it. It is from the Sanskrit and means ‘he who controls the trident’, and as the ODA is a three-headed motor that is being controlled by this protein, it seemed like a brilliant name.

Of the structural techniques you have worked with, including X-ray crystallography and cryo-electron microscopy, which would you say is the most challenging and/or most rewarding?

Crystallography was the most challenging because getting things to crystallize had become quite difficult and it took a lot of effort and a lot of protein. Sometimes it worked and it was beautiful, and very surprising things crystallized, and sometimes it seemed impossible. However, when cryoEM came along it was so impressive because suddenly it opened up all of these other complexes, such as dynactin and dynein, which would have been far too flexible to see by X-ray crystallography. So, that was a big step forwards. Regardless of the challenges, I think they're all enjoyable. I remember, as a PhD student, sitting in the computer graphics room late one night, and the structure of the antibiotic streptomycin bound to the ribosome came up. I knew that I was the first person to ever see that and it explained all this literature. I'd been thinking about it for ages and to suddenly see this structure, it was terribly exciting.

The other thing that is hugely helpful for biologists nowadays is the software AlphaFold2, which has amazing predictive power. You can say ‘I wonder if those two proteins interact’, put it into AlphaFold2, and in many cases you can see almost immediately what this interaction could look like and come up with a hypothesis that you can then test. I think it has really revolutionized the field.

You are an organizer of The Company of Biologists Workshop ‘The Cytoskeletal Road to Neuronal Function’ planned for 2024 – what inspired this idea and what do you hope to take away from this Workshop?

This Workshop was originally scheduled for 2021, but due to the pandemic, it could not go ahead in person. We decided that this sort of meeting was not going to work as well online, so we reapplied for it when applications reopened and we were grateful to be selected again. My involvement came about due to a PhD student in my lab, Helen Foster, who wanted to try and start doing cryo-electron tomography (cryo-ET) of neurons. We've been interested in this approach because neurons are such a good model system for transport because of the need to move proteins and organelles along their axons. This project led to the paper that we published recently in Journal of Cell Biology (JCB), and also got us on the road to doing much more neuronal cell biology. Then, I was talking to Carsten Janke, who is organizing the meeting with myself and Oren Schuldiner, about what we were doing and he suggested applying for one of these Workshops. The goal is to bring together a wide breadth of scientists, from people working on protein structures to people working on neuronal cell biology, all the way up to whole organisms. A lot of these Workshops are aimed at bringing together people from different fields that wouldn't normally interact – and so that seemed to be a really fun thing to do and we're looking forward to it.

Outside of the lab, you are on the Editorial board for Life Science Alliance, and until recently, eLife – what is your opinion on the current publishing models in science and on efforts journals are making to increase the ease and accessibility of publishing?

I really like the model of collaborative reviewing, whereby the reviewers get to know who each other are and discuss their reviews; I think that is very helpful in terms of focusing on what's needed to make a paper better. I also think BioRxiv and preprints are really good, because it means that work can get out there quicker. I'm a big fan of peer review, because it always makes papers better, but actually having the data out there relieves some of those pressures that there used to be. Even with these improvements in the publishing process, there are still some bottlenecks. For example, the speed of the publishing process can still be slow. I realize that journals are under a lot of pressure and there are a lot of manuscripts, but it would be good to keep exploring ways to speed up that process if we could.

One area of publishing that I think is often difficult to discuss is the question of ensuring the experimental design is right and the correct statistical approaches are used. I wonder if the journals could help here, by for example producing clearer statistical guidelines and some documentation of what to do and mistakes to avoid.

An initiative that I think is a very good thing is this push to make all data available. All the raw data should be deposited somewhere so that someone can look at it if they need to. I also think a discussion is needed about trying to standardize this process. In the same way that we require Protein Data Bank files (PDBs) to be deposited or cryoEM datasets to be deposited in a particular way. I think clearer guidelines from journals with their preferred databases could help. I also think the requirement to publish all the raw data encourages us to manage and organize our data better.

Finally, could you tell us an interesting fact about yourself that people wouldn't know by looking at your CV?

I am very fond of a breed of dog called Cardigan corgis. I have a couple of them, one called Velocity and another called Whiston, who's named after an 18th century Physicist and Fellow of Clare College, Cambridge. I've had Corgis all my life and my friends know that I have this slight obsession with them. They and I go for long walks on Sunday mornings. We try to follow a Physics-related theme for their names, and suggestions are welcome for the next one!

Andrew Carter was interviewed by Daniel Routledge, Cross-title Reviews Editor at The Company of Biologists, for Journal of Cell Science. This piece has been edited and condensed with approval from the interviewee.