Intellectual Merit: The information transfer from DNA to protein is not an accurate process; sometime errors in copying the information occur, resulting in the production of a malfunctioning protein. For proteins implicated in cellular differentiation programs, these errors have the potential to produce a heritable change in phenotype in genetically identical cells growing in the same environment. The overall goal of this research is to study the cause and the consequence of transcription errors on cellular differentiation programs using the bacterium Escherichia coli as a model organism. To capture and quantify transient transcription errors that lead to heritable phenotypic changes in genetically identical cells, a well characterized epigenetic switch, the lactose operon, will be used. Under specific conditions, the gene network of lac behaves like a differentiation system with two heritable outcomes that are susceptible to switching from one state to the next due to transcription errors. This research aims to identify novel genes involved in the avoidance of epigenetic switching and the physical alterations responsible for this epigenetic change. The results will provide new insights into the fine-tuning of genetic networks through transcriptional regulation.
Broader Impact: Broader contributions of this project include training and teaching the next generation of scientists from high-school students to post-doctoral fellows, promoting scientific collaborations amongst international teams, and providing novel methods for studying the process of information transfer from DNA to protein that will be made publicly available. This research will be disseminated through peer reviewed journals and scientific meetings to inform the public of the role of the environment on epigenetic modification.
intellectual merit. The transfer of information from cell to cell is crucial for preserving cellular identity. Mutations in DNA can cause permanent phenotypic change and this is responsible for many human diseases and drives evolution. Transient alterations of protein conformation for a subset of proteins, Prions, can also cause phenotypic change and this too is responsible for certain neurological diseases and can drive evolution. Thus errors in the making of DNA or protein have been shown to change phenotype and cause disease, but errors in the intermediate step in the central dogma of molecular biology, mRNA, have not yet been implicated in phenotypic change. During the funding period, we established a new paradigm in phenotypic inheritance: transient errors in the making of proteins, the building block of live, can forever affect the fate of a cell. We show directly that transcription errors provoking frameshifting in an mRNA of a regulator involved in a genetic program, can promote permanent phenotypic change. Like protein conformation changes in prions and mutation in DNA, mRNA errors could have the same implications to disease and evolution. Thus, this finding will impact many if not most fields of biology and medicine including genetics, epigenetic inheritance, molecular and developmental biology, cancer biology and molecular evolution. In addition to establishing a novel role for transcription errors in epigenetic inheritance, we developed technology to capture and measure transcription errors in living cells allowing the study of specific DNA sequences involved in transcription fidelity, which has been previously impossible due to the transient nature of mRNA. broader impacts. The NSF Award has allowed training of the next generation of scientists. We dissiminated our findings by writting a review article and scientific papers in open access journals. We established collaboration between laboratories of different expertise (Computation biology and bacterial Genetics). The principal investigator was also involved in organizing a lab course and participated in job fairs in high school to encorage students to pursue a scientific careers.