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| Name |
Johnston, Mark |
| Location
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University of Colorado School of Medicine |
| Primary Field
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Genetics |
| Secondary Field
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Microbial Biology |
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 Research Interests
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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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