Department of Biological Sciences

School of Natural Sciences and Mathematics

Imagine capturing molecular movements so that each step of an intricate dance could be viewed and analyzed.

That’s essentially what an assistant professor of Biology recently hired by the Department of Molecular and Cell Biology at The University of Texas at Dallas (UTD) aims to do. And he has been given broad authority to accomplish his goals.

Tianbing Xia, Ph.D., pronounced Shia, comes from California Institute of Technology, where he conducted research under Nobel laureate Ahmed H. Zewail, Ph.D. and Richard W. Roberts, Ph.D. Zewail won the 1999 Nobel Prize in chemistry for using rapid-laser techniques to study the action of atoms during chemical reactions. The breakthrough created a new field of physical chemistry known as femtochemistry.

Under Zewail and Roberts, Xia co-published research papers titled, “The RNA-Protein Complex: Direct Probing of the Interfacial Recognition Dynamics and its Correlation with Biological Functions”, and “Context and Conformation Dictate Function in a Transcription Antitermination Switch” among others that look at molecular recognition issues and the intricate dance known as conformational dynamics.

New place, new directions, similar dreams …

Xia says he wants to follow his dreams here. He hopes to bridge the gap between biologists and chemists by sharing ultrafast laser techniques he is developing to help researchers in both disciplines.

“Basically what I am trying to do here is set up two different labs – one is a spectroscopy lab, which requires a half million dollars just to build – the other is a standard biology lab. You could go to most universities and say, ‘I’d like to build a lab,’ and that’s OK. But if you want to build two labs at the same time, that costs a lot of money.

“And then again, where are you going to find the space to house two different laboratories for two different groups?

“It is UTD’s commitment that brought me here. They are willing to set up two labs for a young professor, fresh off into some ideas without the money to do the research,” Xia said.

Laser optics

Trained as a biophysical chemist, he is really two parts chemist and one part biologist, physicist and cinematographer.

"The university wants to develop a program in laser optics. This is the first installment of the institute, so my lab is going to be part of a bigger facility, a bigger plan,” he said.

“And that blends in with my goal,” Xia continued, ”of developing novel structural biology tools, particularly ultrafast laser spectroscopy, to probe nucleic acid and protein structures, nucleic acid-protein interactions, and the central roles that these interactions play in regulating important biological processes,” he said.

Heroes united

Another draw for Xia was the head of the biology department, Don Gray, Ph.D.

“We’d never met before, but he was my hero. When I was in graduate school, I was starting a project and I was reading some papers – I came across a couple of Dr. Gray’s papers – and he really inspired me on how we should think about a particular problem. That pointed me in the right direction, and I was able to finish the project.

“I’m now next to the hero of my graduate research. So that’s pretty nice,” Xia said.

Xia said he realizes a great deal is expected of him now that he has the tools needed to conduct his research.

“Now I have to switch my mind to start learning to manage the research program, not just doing the bench work,” Xia said.

Filming in femtoseconds

hummingbird

Xia describes advancements in spectroscopy and suggests that images of hummingbirds in flight help demonstrate how far we've come in our ability to see.

Xia explained that molecules are not static; they are moving and changing shapes all the time. But in order to view or study molecular movements, ultrafast laser pulses are used to capture the images in femtoseconds, which measures 10 to the minus 15th power of a second. He admits almost nothing happens in that time, “but there is something that happens and that’s what I am trying to probe.”

Xia cited a hummingbird as an example.

“A hummingbird flaps its wings at a rate of 50 beats per second. If you take a camera made 50 years ago, you can observe a blur. With the 'camera' I use, you can see it in slow-motion and capture every single movement that the hummingbird is making with its wings.

“And that will be interesting because while the hummingbird is flapping its wings, maybe its body is coordinating the movement with some other part of its body. So it has to synchronize its whole body, perhaps its head or other part that you would not be able to see without an ultrafast camera," he said.

More than meets the eye

“The dream of every chemist is to be able to shoot a movie of a chemical reaction. When I was in college, entering the world of chemistry, that was the dream. I never thought it could be done. Zewail got it. And that’s why he won the Nobel Prize.

“There is another level of dynamics. Not only in terms of atomic movement, but in terms of energy, where energy goes to excite a molecule to a higher energy level. And this molecule is going to come down. It’s not going to stay at that highly excited level forever. But during this time window, things can happen to this excited state.

“For example, something else can interact with it. Or it might lose or gain an electron and change its electronic properties. When that happens, you are able to probe what energy it adds and how it changes within a certain time scale. The thing that changes the state is probably interacting with it. And if you can capture that process, you might be able to learn how these two things interact with each other.

“There is no limit in time. There’s no limit in space. It’s only how far you can push it that limits our observation. Think about that,” Xia said smiling.

A look back

 Xia started his education in China studying crystallography, the science of imaging molecules in crystals, at Peking University. “That got me interested in molecular structures, so I’ve been a chemist basically,” he said.

" There is no limit in time. There’s no limit in space. It’s only how far you can push it that limits our observation. Think about that ."
-- Tianbing Xia, Ph.D.

When he came to the United States, he attended the University of Rochester in New York for graduate school. He said that’s when he got his first taste of biology.

“I still remember the first day when I joined the lab of Doug Turner. The professor said, ‘Welcome to the wonderful world of RNA!’” Xia said.

“Most people,” Xia started, “are actually interested in proteins and DNA. But the truth is that RNA is a very functional molecule that does a lot of different things. And there is a hypothesis called “RNA World” that actually suggests that before the world of protein, there was the world of RNA, where RNA played the central roles.

“The RNA molecule has been the essential molecule in my research for more than 10 years. It would be hard for me to stay away from RNA molecules. I will always be working with RNA molecules in some way. I want to cultivate a Femto Land of RNA here,” Xia said.

Research interests

“The thing that fascinates me most personally in terms of science,” Xia said, “is the particular problem of molecular recognition. Two molecules that have no sense of seeing other things know they're supposed to get together, form a complex and do what they are designed to do by nature. So it’s a fascinating problem: how do they come together in a specific way and do specific things?

“Molecules can recognize each other in different ways. These different recognition modes can be switching on different time scales. That means that every single molecule is not a rock solid entity. There is heterogeneity built in," Xia said.

“That means they have to deal with this fluidness. There is a fluidity there in the conformation space associated with these molecules. When they come together to form a single conformation, they have to solve the problems themselves of how they are going to do this," Xia said.

He said that chemists want to say they can design things to do whatever they want them to do. For example, if you want to target something, chemists tend to think they can, out of the air, design a molecule that bonds to it.

“My thinking is that if you want to do that, you have to understand what the target is. The target is not a picture, it is a movie. It’s playing back and forth, and the things that you are designing to target it have to be grown to deal with the movement. In order for a real chemist to design things, he has to understand he’s dealing with an ensemble of things. The ultimate goal is better dynamic design,” Xia said.

  • Updated: February 6, 2006