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Joan Steitz

Sterling Professor of Molecular Biophysics and Biochemistry
Yale School of Medicine

Steitz earned her BS in chemistry from Antioch College in 1963. Significant findings from her work emerged as early as 1967, when her Harvard PhD thesis with Jim Watson examined the test-tube assembly of a ribonucleic acid (RNA) bacteriophage (antibacterial virus) known as R17.

Steitz spent the next three years in postdoctoral studies at the Medical Research Council Laboratory of Molecular Biology in Cambridge, England, where she used early methods for determining the biochemical sequence of RNA to study how ribosomes know where to initiate protein synthesis on bacterial mRNAs. In 1970, she was appointed assistant professor of Molecular Biophysics and Biochemistry at Yale, becoming full professor in 1978. At Yale, she established a laboratory dedicated to the study of RNA structure and function. In 1979, Steitz and her colleagues described a group of cellular particles called small nuclear ribonucleoproteins (snRNPs), a breakthrough in understanding how RNA is spliced. Subsequently, her laboratory has defined the structures and functions of other noncoding RNPs, such as those that guide the modification of ribosomal RNAs, microRNAs and several produced by transforming herpesviruses.  

Steitz is an investigator of the Howard Hughes Medical Institute, a member of the American Academy of Arts and Sciences, American Philosophical Society, National Academy of Sciences, the Royal Society of London, and Institute of Medicine. Her many honors include the U.S. Steel Foundation Award in Molecular Biology (1982), the National Medal of Science (1986), the FASEB Excellence in Science Award (2003), the RNA Society Lifetime Achievement Award (2004), Gairdner Foundation International Award (2006), Albany Medical Center Prize in Medicine and Biomedical Research (2008) [shared with Elizabeth Blackburn], the Pearl Meister Greengard Prize (2012), La Grande Médaille 2013 de l'Académie des Sciences, Insititut de France, the Herbert Tabor Award from the  American Society of Biochemistry and Molecular Biology (2015), and the Jonathan Kraft Prize for Excellence in Cancer Research (2016).


"Noncoding RNAs of Viral and Cellular Origin:  insights into evolution"

Noncoding (nc)RNAs play pivotal roles in the regulation of gene expression, but exhibit a diversity of functions whether encoded by cellular or viral genomes.  Our studies of ncRNAs produced by the oncogenic gamma herpesviruses illustrate the habit of viruses to acquire components from their host cells but then utilize them – sometimes in quite different ways – to enhance the viral life cycle.  

One example is the use of RNA elements called ENEs by both viruses and cells to stabilize intronless transcripts by engaging the polyA tail or 3′-terminal A-rich tract in a triple-helical RNA structure that obstructs the initiation of degradation.  Our structural studies of ENEs from the PAN ncRNA of the oncogenic virus KSHV and from the vertebrate long ncRNA MALAT1 have led to unanticipated insights into the structure of RNA triple helices.  More recently, the identification of hundreds of PAN-like ENEs in transposons in non-metazoan species has illuminated how ENE acquisition and intron loss may be coupled.  Thus, such studies provide insights into the evolution of both viruses and their host organisms.

Joan A. Steitz