Our cells depend on thousands of proteins and nucleic acids that function as tiny machines: molecules that build, fold, cut, destroy, and transport all of the molecules essential for life. My group is discovering how these molecular machines work, looking at interactions between individual atoms to understand how they activate gene expression, DNA replication, and small RNA biology.
In Leemor Joshua-Tor’s lab, researchers study the molecular basis of nucleic acid regulatory processes using the tools of structural biology and biochemistry. One such regulatory process is RNA interference (RNAi), in which a small double-stranded RNA triggers gene silencing. Joshua-Tor and her team offered critical insight when they solved the crystal structure of the Argonaute protein and identified it as the long-sought Slicer. They then went on to explore the mechanism of the slicing event. The structure of human Argonaute 2 (hAgo2) bound to a microRNA (miRNA) guide allowed Joshua-Tor and her colleagues to understand how mRNA is cleaved during RNAi. This year, members of the Joshua-Tor lab explored the function of a very similar protein, called Argonaute 1, that has no slicing ability, even though it is almost identical in structure to the slicing hAgo2. Using biochemical methods and mutational analysis, they were able to identify key parts of the protein that are required for slicing activity. The lab also studies the generation of PIWI-interacting RNAs (piRNAs), which serve to protect the genome of germ cells. With colleagues in the Hannon lab, Joshua-Tor’s team also determined the structure and function of Zucchini, a key nuclease in the initial generation of piRNAs in fruit flies. In other work, the lab is exploring the mechanisms of heterochromatin formation and gene silencing through the study of a protein complex called RNA-induced initiation of transcriptional gene silencing (RITS). Joshua-Tor is also well known for her work on the E1 helicase enzyme, which acts to unwind DNA strands during the DNA replication process.
Member of the National Academy of Sciences
Member of the American Academy of Arts and Sciences
2018 Mildred Cohn Award in Biological Chemistry, ASBMB
2014 ACE Women’s Network, New York, Women in Science and Education Leadership Award
Fellow of the American Association for the Advancement of Science (AAAS)
2007 Dorothy Crowfoot Hodgkin Award (Inaugural award), The Protein Society
1996 Beckman Young Investigator Award
Cryo-EM illuminates intricate designs of noroviruses
June 11, 2019
Researchers reconstruct four different strains of the food-poisoning causing norovirus using the groundbreaking cryo-electron microscope.
Norovirus structures could help develop treatments for food poisoning
June 11, 2019
Researchers at CSHL used cryo-EM to reconstruct the structures of four different strains of human noroviruses, which cause food poisoning.
Dr. Leemor Joshua-Tor honored with Mildred Cohn Award from ASBMB
February 2, 2018
Professor Leemor Joshua-Tor receives the American Society for Biochemistry and Molecular Biology’s 2018 Mildred Cohn Award in Biological Chemistry.
Research profile: Leemor Joshua-Tor
November 27, 2017
A CSHL faculty member since 1995, a professor since 2005, Joshua-Tor is among the most distinguished members of the Laboratory community.
Structural view suggests RNAi machinery multiplies its efficiency in repressing gene expression
August 3, 2017
Leemor Joshua-Tor publishes atomic-resolution pictures and an analysis of RNAi machinery
Freeze-frames of enzymes in action have implications for a new cancer treatment concept
July 3, 2017
TUTase enzymes interact with let-7, a regulator of development; targeting them could help control certain cancers.
CSHL’s Dr. Leemor Joshua-Tor is elected to The National Academy of Sciences
May 2, 2017
Professor Leemor Joshua-Tor has been elected to The National Academy of Sciences (NAS).
CSHL’s Dr. Leemor Joshua-Tor Elected to American Academy of Arts and Sciences
April 14, 2017
Professor Leemor Joshua-Tor is among 228 newly elected members of The American Academy of Arts and Sciences
Protein complex that takes first steps in human DNA replication dance is captured at high atomic resolution
March 16, 2017
Human ORC complex captured in action in x-ray crystallography and cryo-EM
Alumnus Niraj Tolia works toward a modern malaria vaccine
June 8, 2015
Alumnus receives five-year Investigators in the Pathogenesis of Infectious Disease Burroughs Wellcome Fund grant to fight malaria.
Faehnle, C. R. and Walleshauser, J. and Joshua-Tor, L. (2017) Multi-domain utilization by TUT4 and TUT7 in control of let-7 biogenesis. Nat Struct Mol Biol, 24(8) pp. 658-665.
Tocilj, A. and On, K. F. and Yuan, Z. and Sun, J. and Elkayam, E. and Li, H. and Stillman, B. and Joshua-Tor, L. (2017) Structure of the active form of human Origin Recognition Complex and its ATPase motor module. Elife, 6
Kuhn, C. D. and Wilusz, J. E. and Zheng, Y. and Beal, P. A. and Joshua-Tor, L. (2015) On-Enzyme Refolding Permits Small RNA and tRNA Surveillance by the CCA-Adding Enzyme. Cell, 160(4) pp. 644-658.
Faehnle, C. R. and Walleshauser, J. and Joshua-Tor, L. (2014) Mechanism of Dis3l2 substrate recognition in the Lin28-let-7 pathway. Nature, 514(7521) pp. 252-6.
Elkayam, E. and Kuhn, C. D. and Tocilj, A. and Haase, A. D. and Greene, E. M. and Hannon, G. J. and Joshua-Tor, L. (2012) The structure of human argonaute-2 in complex with miR-20a. Cell, 150(1) pp. 100-110.Additional materials of the author at
CSHL Institutional Repository