UTMB

Kyung H. Choi, Ph.D.,
Assistant Professor

Faculty

Kyung H. Choi, Ph.D.

About the Lab

Our research focuses on the structure and mechanism of viral replication and infection machinery using X-ray crystallography and cryo-electron microscopy. High-resolution X-ray crystal structures of individual component proteins can be fitted into lower resolution cryo-EM density maps to generate pseudo-atomic structure of large macromolecular complexes.

Virtually all RNA viruses carry out viral genome replication using a large replication complex composed of RNA, viral replicases, and cellular proteins. However, specific protein-protein and protein-RNA interactions are poorly understood. We are interested in the structure of individual replication enzymes and their protein-protein, and protein-RNA complexes in human and animal viruses. These viruses include hepatitis C virus, bovine viral diarrhea virus (BVDV), dengue virus, human coronavirus (SARS), and hantan virus. Our structural studies will help develop antiviral therapeutics for animal and human diseases caused by these RNA viruses.

Tailed bacteriophages have to deliver their genetic information into the host cell’s cytoplasm across cell membranes. The tail machinery, composed of multiple protein components, attaches to the cell membrane and transports genomic DNA into the cell. We use bacteriophage N4 as a model system to study the mechanism of genome and protein transport from the virus into the host cell. N4 packages dsDNA as well as one or two copies of a 3,500-amino acid RNA polymerase (vRNAP) inside the capsid, which is then ejected into host cell upon infection. In collaboration with Dr. Lucia Rothman-Denes laboratory (University of Chicago), we are determining the structure of N4 virions as well as tail component proteins.

Interview with Dr. Choi

– by Debashish Sahu, 1st year BSCB Student

"Visual observation is attractive and most of the times seeing is believing"
–Dr. Choi, on research.

Dr. Kyung (Kay) Choi leapt into scientific field from her initial work at Boston University where she discovered her zeal towards the structure & function of cystine proteases. During her postdoctoral research training, she worked with Dr. Karen Allen and Dr. Michael Rossmann , where she investigated the mechanistic enzymology of fructose-1,6-bisphosphate aldolases using a combination of X-ray crystallography & enzyme kinetics and structural studies of Flaviviridae replicases and bacteriophages using X-ray crystallography, cryo-electron microscopy, and high-throughput techniques.

Dr.Choi is a highly enthusiastic scientist and pursues her scientific research with a keen interest on understanding the structural biology of viruses. My utmost curiosity instilled me to ask her on what made her interested in viruses, to which she replied, “Viruses defies the definition of life”.

UTMB being a medical school has one of the best structural biology department equipped with state-of-art modern structural biology facilities has drawn many good faculties like Dr.Choi. Dr.Choi is impressed by the fact that the BSCB programme is unique with diverse backgrounds in chemisty and physics, which aids in solving problems in biology. This is advantageous as it gives a new perspective towards approaching a biological problem. Further, the mind-blowing BSCB seminars on cutting-edge science, an integral part of the BSCB curriculum attracted her the best.

Dr. Choi adores the famous Watson and Crick and said that they are her scientific idols for the fact that Watson had the enthusiasm & the drive to solve a problem, while Crick had the scientific insight. She believes that this combination is certainly needed to be successful in scientific research. When I asked her on what motivated her to do research, she replied, “Curiosity, scientific curiosity”

Dr. Choi’s scientific career started with purification of cystine protease from ginger and studying its crystal structure & specificity. She is attracted towards structural biology because when she sees a structure for the first time, she is contemplated with new questions that can be answered differently. She strongly believes in critical thinking and loads of imagination to find solutions to scientific problems.

"Enjoy the ride!"
–Dr. Choi's message to the future scientists in the BSCB.

Dr. Choi considers the specificity of cystine protease towards proline & the structure of virus RNA polymerase (which carries out denovo RNA synthesis without a primer) as the most significant scientific observation she has made in science. She is proud to have solved the structure of virus polymerase complexed with GTP, which has given a new insight into the denovo RNA systhesis. Further, she admires the rotation of F1 ATPase, which marked a new era in the field of single molecule research, which she claims is the most beautiful scientific observation in all of science. Dr. Choi assertively sees herself solving the structure of replication complex and understanding the transportation of protein & DNA across the membrane by bacterophage in a few years. Dr. Choi feels that the purification of the receptor might be limiting step towards achieving this goal. Dr. Choi expects a good student/scientist to have the enthusiasm towards science & the scientific attitude which gives a new dimension to a biological problem.

She points out to the fact that graduate study is time consuming (sometimes more than 5 years) and students have to really enjoy their scientific journey. She’s impressed with the BSCB students because unlike other biological graduate schools the students get to choose a specific field to work on.