[Edit]Riboswitches bind cellular metabolites and control gene expression

Segments of RNA, typically embedded within the 5'-untranslated region of a vast number of bacterial mRNA molecules, have a profound effect on gene expression through a previously-undiscovered mechanism that does not involve the participation of proteins. In many cases, riboswitches change their folded structure in response to environmental conditions (e.g. ambient temperature or concentrations of specific metabolites), and the structural change controls the translation or stability of the mRNA in which the riboswitch is embedded. In this way, gene expression can be dramatically regulated at the post-transcriptional level.^[28]

[Edit]Small rna molecules regulate gene expression by post-transcriptional gene silencing

Another previously unknown mechanism by which RNA molecules are involved in genetic regulation was discovered in the 1990s. Small RNA molecules termed microRNA (miRNA) and small interfering RNA (siRNA) are abundant in eukaryotic cells and exert post-transcriptional control over mRNA expression. They function by binding to specific sites within the mRNA and inducing cleavage of the mRNA via a specific silencing-associated RNA degradation pathway.^[29]

[Edit]Noncoding rna controls epigenetic phenomena

In addition to their well-established roles in translation and splicing, members of noncoding RNA (ncRNA) families have recently been found to function in genome defense and chromosome inactivation. For example, piwi-interacting RNAs (piRNAs) prevent genome instability in germ line cells, while Xist (X-inactive-specific-transcript) is essential for X-chromosome inactivation in mammals.^[30]

[Edit]proto-anti-codon rnAs (pacRnAs)

Following predictions on the proto-tRNA structure gleaned from archaeal genome projects, it was discovered that an RNA auto-aminoacylating system would have been capable of recognizing and ligating only a small number of L-amino acids. Remarkably, the predicted binding sequences are complementary sequences to the codons of the genetic code and hence are called proto-anti-codon RNAs (pacRNAs).^[31] When the amino acid binding pocket provided by the anti-codon sequence consists of a pair ofpyramidines followed by an adenine base, the pacRNA sequence is ill suited to ligating amino acids. Remarkably these sequences are related to the stop codons, which may have evolved because of they were evolutionarily unspecified signal sequences for pacRNA recruitment. The pacRNA model posits that translational codons evolved long after an aminoacylated RNA world, during which aminoacylated RNAs with exposed proto-anti-codons were recruited to cis-acting codon sequences on functional RNAs. Thus, the pacRNA model appears to unify several outstanding biological questions related to the evolutionary origins of the codon table, universal homochirality in addition to making specific prediction about the evolution of life's informational molecules.

[Edit]Nobel Laureates in rna biology

See also: List of RNA biologists

Name	Dates	Institution	Awards
Altman, Sidney	born 1939	Yale University	1989 Nobel Prize in Chemistry
Baltimore, David	born 1938	California Institute of Technology	1975 Nobel Prize in Physiology or Medicine
Barré-Sinoussi, Françoise	born 1947	Pasteur Institute	2008 Nobel Prize in Physiology or Medicine
Blackburn, Elizabeth	born 1948	University of California, San Francisco	2009 Nobel Prize in Physiology or Medicine
Brenner, Sydney	born 1927	Salk Institute	2002 Nobel Prize in Physiology or Medicine
Cech, Thomas	born 1947	University of Colorado, Boulder	1989 Nobel Prize in Chemistry
Crick, Francis	1916–2004	Salk Institute	1962 Nobel Prize in Physiology or Medicine
Dulbecco, Renato	born 1914	CNR Institute of Biomedical Technologies (Italy)	1975 Nobel Prize in Physiology or Medicine
Fire, Andrew	born 1959	Stanford University	2006 Nobel Prize in Physiology or Medicine
Gilbert, Walter	born 1932	Harvard University	1980 Nobel Prize in Chemistry
Greider, Carol	born 1961	Johns Hopkins University	2009 Nobel Prize in Physiology or Medicine
Holley, Robert	1922–1993	Cornell University	1968 Nobel Prize in Physiology or Medicine
Jacob, François	born 1920	Pasteur Institute	1965 Nobel Prize in Physiology or Medicine
Khorana, H. Gobind	1922–2011	Massachusetts Institute of Technology	1968 Nobel Prize in Physiology or Medicine
Klug, Aaron	born 1926	Medical Research Council (UK)	1982 Nobel Prize in Chemistry
Kornberg, Roger	born 1947	Stanford University	2006 Nobel Prize in Chemistry
Mello, Craig	born 1960	University of Massachusetts Medical School	2006 Nobel Prize in Physiology or Medicine
Monod, Jacques	1910–1976	Pasteur Institute	1965 Nobel Prize in Physiology or Medicine
Montagnier, Luc	born 1932	Pasteur Institute	2008 Nobel Prize in Physiology or Medicine
Nirenberg, Marshall	1927–2010	National Institutes of Health (USA)	1968 Nobel Prize in Physiology or Medicine
Ochoa, Severo	1905–1993	New York University	1959 Nobel Prize in Physiology or Medicine
Temin, Howard	1934–1994	University of Wisconsin, Madison	1975 Nobel Prize in Physiology or Medicine
Ramakrishnan, Venkatraman	born 1952	Medical Research Council (UK)	2009 Nobel Prize in Chemistry
Roberts, Richard	born 1943	New England Biolabs	1993 Nobel Prize in Physiology or Medicine
Sharp, Philip	born 1944	Massachusetts Institute of Technology	1993 Nobel Prize in Physiology or Medicine
Steitz, Thomas	born 1940	Yale University	2009 Nobel Prize in Chemistry
Szostak, Jack	born 1952	Harvard University	2009 Nobel Prize in Physiology or Medicine
Todd, Alexander	1907–1997	University of Cambridge	1957 Nobel Prize in Chemistry
Watson, James	born 1928	Cold Spring Harbor Laboratory	1962 Nobel Prize in Physiology or Medicine
Yonath, Ada	born 1939	Weizmann Institute of Science	2009 Nobel Prize in Chemistry