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Johns Hopkins University logoProgram in Molecular Biophysics
Rachel Green 

Rachel Green

Professor
Department of Molecular Biology and Genetics
School of Medicine


B.S. 1986, University of Michigan
Ph.D. 1992, Harvard University

ragreen@jhmi.edu

702A PCTB
725 N. Wolfe Street
Baltimore, MD 21205

Office: 410-614-4922
Lab: 410-614-492
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The ribosome is the two-subunit macromolecular complex responsible for the translation of the genetic code into functional polypeptides. The ribosome is composed of RNA (3 large rRNAs in bacteria) and protein (more than 50 r-proteins in bacteria) in a mass ratio of about 2 to 1. We are interested in understanding how this ribonucleoprotein machine catalyzes and coordinates the complex molecular events of translation. These studies may reveal important details that impact on the function of other RNP machines such as the spliceosome and telomerase and may uncover clues that help us to think about the early origins of life and the specifics of the 'RNA world'. Further, as ribosomes are the target of many clinically relevant anti-microbial agents (erythromycin, chloramphenicol, and aminoglycosides), there are modern day applications for drug development from what we learn in our basic studies.

The work in our laboratory focuses on a number of the different steps in the translation cycle including decoding, peptide bond formation, translocation and peptide release. Recent advances in X-ray crystallography have provided us with atomic resolution views of the large and small subunits of the ribosome. These views have revealed that the functional core of the ribosome is predominantly composed of RNA and has identified phylogenetically conserved regions of particular functional interest. We are interesting in understanding the molecular mechanism of translation with a particular challenge being to define the dynamics of this RNP machine during the multiple different events of the translation cycle. We use a variety of mutational approaches targeting the ribosome itself as well as the translation factors and tRNA and a set of well-defined pre-steady state assays to evaluate the contributions made by specific components to the function of this RNP machine. We currently perform these experiments in a reconstituted E. coli or yeast translation system focusing primarily on the events of termination and recycling. A third area of interest focuses on miRNA-mediated gene silencing in Drosophila, using primary cell culture approaches to study the timing and regulation of the relevant steps.

Selected Publications
Djuranovic, S., A. Nahvi, and R. Green. (2011) A parsimonious model for gene regulation by miRNAs. Science 331:550-553.

Eyler, D.E., and R. Green. (2011) Distinct response of yeast ribosomes to a miscoding event during translation. RNA 5:925-932.

Zaher, H.S., J.J. Shaw, S.A. Strobel, and R. Green. (2011) The 2'-OH group of the peptidyl-tRNA stabilizes an active conformation of the ribosomal PTC. EMBO J. 12:2445-2453.

Shoemaker, C.J., D.E. Eyler, and R. Green. (2010) Dom34:Hbs1 promotes subunit dissociation and peptidyl-tRNA drop off to initiate no-go decay. Science 330:369-372.

Zaher, H.S., and R. Green. (2010) Kinetic basis for global loss of fidelity arising from mismatches in the P-site codon:anticodon helix. RNA 16:1980-1989.

Zaher, H.S., and R. Green. (2010) Hyperaccurate and error-prone ribosomes exploit distinct mechanisms during tRNA selection. Mol. Cell 39:110-120.

He, S., and R. Green. (2010) Visualization of codon-dependent conformational rearrangements during translation termination. Nat. Struct. Mol. Biol. 17:465-470.

Djuranovic, S., M.S. Zinchenko, J.K. Hur, A. Nahvi, J.L. Brunelle, E.J. Rogers, and R. Green. (2010) Allosteric regulation of Argonaute proteins by miRNAs. Nat. Struct. Mol. Biol. 17:144-150.

Nahvi, A., C.J. Shoemaker, and R. Green. (2009) An expanded seed sequence definition accounts for full regulation of the hid 3’UTR by bantam miRNA. RNA 15:814-822.

Zaher, H.S., and R. Green. (2009) Quality control by the ribosome following peptide bond formation. Nature 457:161-166.

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