By Eugene Nester
Department of Microbiology
Charles Yanofsky will present the Department of Microbiology’s 14th Annual Helen R. Whiteley Lecture, RNA-Based Regulation of the Genes of Tryptophan Synthesis and Degradation in Bacteria, at 4 p.m., Thursday, April 12 in the Physics & Astronomy auditorium, A118.
Yanofsky has made significant contributions to understanding the regulation of gene expression. His studies have focused on the genes of tryptophan biosynthesis, largely in Escherichia coli and Bacillus subtilis. His detailed biochemical and genetic analysis of this pathway achieved over his entire scientific career has been rewarded in ways he probably did not conceive when he initiated his studies some 50 years ago. Using the power and tools of genetics in the infancy of microbial genetics, he defined many of the key biochemical steps of tryptophan biosynthesis. In a landmark study that ranks among the most significant in all of molecular genetics, he and his colleagues demonstrated that there was colinearity between gene structure and protein structure, i.e. the sequence of nucleotides in the DNA encoding the enzyme tryptophan synthase corresponded to the sequence of amino acids in the tryptophan synthase protein. These studies were critical to understanding the relationship between the genetic information in DNA and the proteins in the DNA.
In recent years, his attention has turned to the regulation of gene expression, another arena in which he has made significant contributions through the imaginative use of microbial genetics and biochemistry. For many years it was widely believed that all regulatory processes involved only DNA and proteins. However, the studies of Yanofsky and others showed that mRNA, other RNAs, as well as other types of molecules, provide the basis for highly complex and sophisticated regulatory processes. In particular, Yanofsky’s studies on the regulation of genes of tryptophan biosynthesis and degradation have revealed the numerous ways that this pathway is controlled in two different bacteria. These processes include repression, feedback inhibition, translational coupling, polarity, mRNA degradation and RNA-based transcriptional attenuation. Interestingly, the mechanisms that these two bacteria, E. coli and B. subtilis, use to sense and respond to the level of tryptophan in the environment differ appreciably. How these two ‘simple’ organisms optimize gene expression through highly complex and sophisticated mechanisms will be the subject of Yanofsky’s presentation.
Yanofsky received his bachelor’s degree from the City College of New York in 1948 and his doctoral degree from Yale University three years later. He continued at Yale as a research assistant for two years and then went to Western Reserve University Medical School as an assistant professor for four years. In 1958, he left for Stanford University, where he is currently an emeritus professor of biology.
His studies have merited numerous awards. These include the Albert Lasker Award in Basic Medical Research, Abbot-ASM Lifetime Achievement Award and the National Medal of Science. He also received the H&S Dean’s Award for Lifetime Achievement in Teaching at Stanford. He is a member of the National Academy of Sciences and a foreign member of the Royal Society.
This lecture honors the memory of Helen R. Whiteley, who served as a professor in the Department of Microbiology at the University of Washington from 1953 until her death in December 1990. Past president of the American Society for Microbiology (ASM) and chairman of the ASM Publications Board, Whiteley was also an eminent scientist whose research focused on control of viral transcription in Bacillus subtilis phages, the properties of RNA polymerases, and the cloning and expression of the crystal protein gene of Bacillus thuringiensis.