H. Mark Johnston

University of Colorado Health Sciences Center


Primary Section: 26, Genetics
Secondary Section: 44, Microbial Biology
Membership Type:
Member (elected 2022)

Biosketch

Mark Johnston is a molecular geneticist recognized for his research into how yeast cells sense and respond to nutrients. He is known for his work on regulation of the GAL genes; on how glucose regulates gene expression; and for pioneering genomics approaches to identify gene regulatory sequences. Born and raised in central Wisconsin, Johnston received his BA degree from that state's university in Madison, and earned his PhD from the University of California-Berkeley (with a sojourn at the University of Utah). Following a fellowship in the Biochemistry Department of Stanford University, he joined the faculty of the Department of Genetics at Washington University in St. Louis in 1983. He became Chair of the Department of Biochemistry and Molecular Genetics of the University of Colorado School of Medicine in 2009, retiring in 2019. Johnston's service to the genetics community included serving as front man for the US contribution to the international yeast genome sequencing project; leading the US contribution to the international yeast gene deletion project; serving for 12 years as Editor in Chief of the Genetics Society of America's (GSA) flagship journal GENETICS; and serving on the GSA's Board of Directors for 14 years, including as President in 2004.

Research Interests

Mark Johnston has long been interested in how cells sense and respond to nutrients. His PhD thesis describing how bacterial cells regulate expression of the his genes for histidine biosynthesis contributed to understanding of transcriptional attenuation as a gene regulatory mechanism in bacteria. He spent most of his career studying how the single-celled eukaryotic organism yeast manages its metabolism of sugars. He contributed to our understanding of the mechanism of regulation of the GAL genes for galactose utilization, including how glucose, yeasts' preferred carbon source, represses GAL gene expression. That led to discovery of glucose sensors that are the founding members of a novel class of nutrient receptors evolved from nutrient transporters, providing a new paradigm for nutrient sensing. These novel glucose receptors sense extracellular glucose and generate an intracellular signal that induces expression of genes encoding bona fide glucose transporters. His laboratory helped reveal how that signal is transduced to transcription factors that regulate gene expression. He also employed genomics approaches to study mechanisms of transcriptional regulation, including comparative DNA sequence analysis to identify gene regulatory sequences and genomic targets of transcription factors.

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