Hideko Kaji, PhD

Contact Dr. Kaji

1020 Locust Street
Room 456A JAH
Philadelphia, PA 19107

(215) 503-6547
(215) 923-7343 fax

Medical School

PhD, Purdue University


Recipient of the Special Fellowship from the Japanese Government, 1952-1954
Recipient of Association of American College Women Club Fellowship, 1954
Recipient of University of Nebraska Foundation Fellowship, 1954-1956

Recipient of Purdue Foundation Fellowship, 1956 -1958
Recipient of Eli Lilly Fellowship, 1958 -1959
Recipient of Senior NIH Fellowship, 1972 -1973
Recipient of Max Planck Gesellschaft Foundation Fellow, 1972 -1974
Fellow of the American Association for the Advancement of Science, 2011

Board Memberships

Elected Board Member, Scientific Counselor, National Institutes of Health, 1985 -1987

Expertise and Research Interests

Translation (protein synthesis) from aminoacyl tRNA consists of four consecutive steps; initiation, elongation, termination, and recycling of the machinery of the protein synthesis for the next round of translation. We discovered the fourth step. We are working on the this step in prokaryotes and eukaryotes. We discovered that a protein called ribosome recycling factor (RRF) is necessary for this step in prokaryotes. This protein is essential for all organisms except for Archaea. In collaboration with other laboratories, we determined the structure of RRF and the ribosomal binding site of RRF. RRF moves in the inter-subunits space of the ribosome during its function like tRNA does. We have recently discovered RRF functions to rescue stalled ribosomes with the help of termination factors RFs in the absence of the termination codon. This is being submitted.
In the eukaryotic cytoplasm, there is no equivalent of RRF for recycling ribosomes. In search for the recycling factor, we discovered recently that eEF3 and ATP functions to disassemble the post-termination complex. The P-site bound peptidyl tRNA is hydrolyzed by eRF1 and 3 to form post-termination complexes. For convenience, we can use puromycin, an antibiotic which reacts with peptidyl tRNA on the P-site to form peptidyl puromycin. Since eEF3 is limited to yeast, the system is a good target of possible anti-fungal agent. Since eEF3 is absent in higher eukaryotes like humans, there must be other protein factor responsible ribosome recycling in the cytoplasm. We are going to find out this protein. These studies are basis of fundamental biology, protein synthesis. The factor we are after may play important role in tumor formation, aging, and development.

Other Expertise

Laboratory Staff
Postdoctoral fellows:
1) Dr. Nobuhiro Iwakura, Ph.D. He received his Ph.D in microbiology at Niigata School of Medicine, Japan under the guidance of Professor Tatsuo Yamamoto in 2005. He joined our laboratory right after his Ph.D and has been with us since. He works on prokaryotic ribosome recycling system. He has made important contributions and they are listed in the list of academic report of CV of Hideko Kaji.
2) Dr. Shinya Kurata, Ph.D He received his Ph.D in biochemistry and molecular biology at School of Engineering , Tokyo University, Japan under the guidance of Professor Tsutomu Suzuki in 2007. He joined our laboratory right after his Ph.D and has been with us since. He discovered that ribosome recycling in yeast is catalyzed by elongation factor 3 and ATP. This seminal discovery was reported in Proc. Nat. Acad. Sci (June 2010). He is continuing studies on the eukaryotic ribosome recycling.

Medical Students:
1) Andrew Baron; He is a second year Jefferson Medical College student and works as a work study student. His work is related to both eukaryotic and prokaryotic ribosome recycling.
2) Tomoya Inukai: He is a fourth year Medical Student of Niigata School of Medicine (the Japanese Medical School takes students from high school and educate them for total of six years). He is a part time student who works on eukaryotic ribosome recycling system together with Dr. Shinya Kurata.
3) Sohei Abe: He is a fourth year Medical Student of Niigata School of Medicine. He is a part time student who works on prokaryotic ribosome recycling system in prokaryotes. He collaborates with Dr. Nobuhiro Iwakura.




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