1. 논문관련 분야의 소개, 동향, 전망을 간단히 설명

Francois Jacob is said to have remarked, "The dream of every cell is to become two cells." In this respect, from my simple-minded physicist's point of view, there are three basic steps: duplication of the genetic information, segregation of the duplicated chromosomes, and division of the cell. The field I am interested in, which my paper concerns, is the second part, namely, chromosome segregation in bacteria. If you open your favorite undergraduate textbook, you will find a lot of information about chromosome segregation in eukaryotic organisms, but very little on bacteria. The reason is very simple: bacteria are much smaller than eukaryotes, typically an order of magnitude smaller in linear dimensions, thus you need a much better technology to be able to see what is happening inside bacterial cells. Such technology has become finally realized in the form of visualization experiments in the last few years. For instance, you can visualize specific loci along the chromosome using genetic engineering and fluorescent molecules, and follow their positions inside a cell during the cell cycle. Thanks to these techniques, the interests in this fundamental process in biology have been growing very rapidly. Unfortunately, despite all the impressive progress made so far, the nature of driving force underlying bacterial chromosome segregation has remained elusive. This is where we come in, I mean, from physics.

Well, to understand the current paradigm, we need to know a little bit of history. The first and the most influential model was suggested by Francois Jacob in his celebrated "replicon paper" in 1963. Basically, he and others hypothesized that the origin of replication of E. coli chromosome is attached to the plasma membrane. Then, insertion of membrane material between the two origins enables duplicating chromosomes to be segregated passively by cell elongation. But the slow elongation of bacterial cells was not consistent with the rapid and abrupt nature of chromosome segregation, which is one of the main findings in recent years, i.e.,the visualization experiments mentioned above. This led researchers to suspect eukaryotic-like mechanisms based on active cytoskeletal proteins. What we proposed in our paper is something very different; conformational entropy of duplicating DNA might be enough for bacteria to segregate their chromosomes.

As far as I see, the future is very bright because of (a) new technological development (b) the fundamental-ness of the problem itself. So far, large fraction of the community has been investing their efforts on discovering proteins that might be responsible for DNA segregation, such as MukBEF, MreB, and so on, which has not been a total success for bacteria. I hope and believe that this trend is going to be complemented by more physical approaches.

- 연구과정에서 생긴 에피소드

Nothing much unusual, except the moment I saw my results on Caulobacter. Actually, it was a very strange experience because, usually, we want to publish our results in top journals such as Nature, Science, Cell, and so on, for whatever reasons; when I saw the computer generated trajectories of Caulobacter loci during replication for the first time, I said to myself "This is it. I don't care where it is published." I hope you understand what this means. I've had this kind of experience only once so far.

2.현재 소속기관 또는 연구소에 관한 소개를 부탁드립니다.

AMOLF stands for 'Atomic and Molecular Physics' in Dutch, and it is one of the most prestigious interdisciplinary research institutes in Europe. Basically, most of us has physics background and is working at the interface between physics and biology, taking both theoretical and experimental approaches. There is very active collaboration among us; also national and international, and with biologists. I myself collaborate with biologists and physicists spread in Canada, the US, France, and of course in Holland.

3.연구활동 하시면서 평소 느끼신 점 또는 자부심, 보람

I am having a lot of fun thinking/doing science, that's about it. I even enjoy the long period of frustrations between the short, euphoric periods of 'eureka'.

4.이 분야로 진학하려는 후배들 또는 유학준비생들에게 도움이 되는 말씀을 해 주신다면?

I am not quite sure. Bacterial chromosome segregation is certainly exciting field at the moment, and will continue to be so for quite some time. Being in the right place at the right time is quite important, and working with the right people is also crucial, and I can say that I have been quite lucky indeed. However, one should do what she/he likes, instead of something "promising". For those who are not sure what to do, I highly recommend Francois Jacob's beautiful autobiography `The Statue Within'; this has been one of the most important references in my decision-making processes, and I can imagine to many others as well.

5. 연구활동과 관련된 앞으로의 계획이 있으시다면?

I have too many ideas these days. I am currently constructing an "artificial cell" type environment using microchannels to study more basic physical properties of bacterial chromosomes. This of course includes test of my entropy-driven segregation model. Another passion of mine is evolution, and this project also involves bacteria and microfluidics. This is going to be one of my main projects in the coming years. Of course, I am a theoretician by training, and there are quite a few theoretical physics problems inspired by DNA segregation, which I am doing some collaborations with people in the Netherlands and Canada.

6.다른 하시고 싶은 이야기들....

I hate boundaries of any kind, boundaries that divide people; between ideologies, religions, races, classes, and so on. Such boundaries exist in academia too, and I always try to cross them. To understand nature, we should employ whatever methods that could help, whether it is biological or physical, experimental or theoretical. Of course, we should have fun too.

[Finally, please excuse my responses in English. I sincerely would have tried in Korean if time had been allowed…]