Microbiology, Virology and Parasitology Program

Address

203 Johnson Pavilion (office)
221 Johnson Pavilion (lab)
3610 Hamilton Walk
Philadelphia, PA 19104-6076

Office tel.: 215-898-8828
Lab tel.: 215-898-6524
Fax: 215-573-2221
E-mail: kaji@mail.med.upenn.edu

Link(s)

Dr. Kaji at the Dept of Microbiology

Education

Tokyo University, Pharmaceutical Sciences, BS, 1954

Johns Hopkins University, Molecular Biology, Biochemistry, PhD, 1958

Research Interests

• Mechanism of protein biosynthesis.

Key words: Ribosome Recycling Factor, RRF

Search PubMed for articles

Description of Research

We work on elucidation of the mechanism of protein synthesis. Our first major finding was the discovery of binding of tRNA to programmed ribosomes. This finding was essential for elucidation of genetic code by other laboratories. Another major discovery is the fourth step of protein synthesis. This is the step where recycling of the machinery of protein synthesis for the next round of translation takes place. We are currently working on 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 organism except for Archaea. In collaboration with other laboratories, we determined the structure of RRF and the ribosomal binding site of RRF. RRF moves on the ribosome during its function like tRNA. Currently, we are working on the molecular mechanism of the action of this factor. For eukaryotes, the fourth step of protein synthesis is catalyzed by eEF2 (homologue of EF-G) and ATP. eEF2 uses GTP for the elongation step (translocation) but for recycling it uses ATP. Currently we are establishing that the eEF2/ATP involve in the disassembly of the post-termination complexes.

Recent Publications

Hirokawa, G., Demeshkina, N., Iwakura, N., Kaji, H. and Kaji, A. (2006) The ribosome recycling step: Consensus or Controversy? Trends in Biochemical Sciences. Volume 31 No 3 144-149.

Demeshkina, N., Hirokawa, G., Kaji, A., and Kaji,H. (2007) Novel activity of eukaryotic translocase, eEF2: dissociation of the 80S ribosome into subunits with ATP but not with GTP. Nucleic Acids Research, Pgs 1-11. IN PRESS.

Borovinskaya, M.A., Pai, R.D., Zhang, W., Holton, J.M., Hirokawa, G., Kaji, H., Kaji, A., and Cate, J.H.D. (2007) Structural basis for aminoglycoside inhibition of bacterial ribosome recycling. Nature Structural Biology and Molecular Biology. In Press.

Barat, C., Datta,P.P., Raj,S.V., Sharma,M.R., Kaji,H., Kaji, A., and Agrawal,R.K. Progression of the Ribosome Recycling Factor through the ribosome dissociates the Two Ribosomal Subunits. (2007) Molecular Cell. In Press.

Hirokawa, G., Kaji, H., Kaji, A., Inhibition of Anti-Association Activity of Translation Initiation Factor 3 by Paromomycin. (2007) Antimicrob Agents Chemother. Vol 51., Pgs 175-80.

Lab

Rotation Projects

Ribosome recycling factor in eukaryote
(The project is conducted with close collaboration with Dr. Hideko Kaji, professor of Biochemistry and Molecular biology, Jefferson Medical College.)

Lab personnel:

Dr. Natalia Demeshkina, Postdoctoral Fellow
Dr. Nobu Iwakura, Postdoctoral Fellow
Dr. Musturi Venkataramana