Jeffrey N. Strathern, Ph.D.
- Center for Cancer Research
- National Cancer Institute
- Building 558, Room 4
- Frederick, MD 21702-1201
Two general areas of research were pursued in our section: mechanisms of genetic recombination and the fidelity of transcription. We focused on the area of genetic recombination in general and double-strand-break repair in particular. DNA palindromes are thought to be a common mechanism of gene amplification found in tumor cells. However, palindromes are particularly difficult to investigate because they are difficult to clone and difficult to sequence. We created yeast strains that tolerate DNA palindromes and developed a system in which they can be generated and we also developed a method to determine their sequence.
Areas of Expertise
1) genetic recombination 2) gene regulation
In the area of genetic recombination and DNA damage repair, we focused on the area of the accuracy of genetic recombination in general and double-strand-break repair in particular. We demonstrated that the DNA synthesis associated with genetic recombination has substantially lower fidelity than that found in general cell duplication. At least two different DNA polymerases have roles in this elevated mutation rate: Base substitutions reverting a non-sense allele are dependent on the translesion polymerase, Pol zeta, encoded by REV3, whereas reversion of frameshift alleles is REV3 independent. We investigated the mechanism of double-strand-break repair and the proteins involved in controlling the fidelity of DNA synthesis during this process. We then extended this research to demonstrate meiotic recombination is also mutagenic. DNA palindromes are thought to be a common mechanism of gene amplification found in tumor cells. However, palindromes are particularly difficult to investigate because they are difficult to clone and difficult to sequence. We created yeast strains that tolerated DNA palindromes and developed a system in which they can be generated. We also developed a method to sequence DNA palindromes. We applied those tools to the characterization of DNA palindromes isolated from human tumor cell lines.
We also studied the fidelity of transcription; again, this was historically a difficult problem. We developed a genetic screen to identify mutants with reduced fidelity. We isolated mutations that reduce the fidelity of transcription and identified mutations in several subunits of RNA polymerase that result in error prone transcription. Through collaborative studies, we studied the consequences of increased transcription error rates.
Our collaborators were Stephen Hughes, Michael Kashlev, Mark Lewandoski and Ding Jin, NCI.
Isolation and characterization of RNA polymerase rpoB mutations that alter transcription slippage during elongation in Escherichia coli
The fidelity of transcription: RPB1 (RPO21) mutations that increase transcriptional slippage in S. cerevisiae
Jeffrey N. Strathern, Ph.D.
Dr. Strathern obtained his Ph.D. from the Molecular Biology Institute at the University of Oregon in 1977, then moved to Cold Spring Harbor Laboratory where he became a senior staff member with the Yeast Genetics Laboratory. In 1984, he joined the ABL-Basic Research Program at the NCI's Frederick Cancer Research Development Center (now NCI-Frederick). His research remains centered on aspects of gene regulation, transcription fidelity, and genetic recombination as revealed by studies in yeast. In 1999, Dr. Strathern joined the Division of Basic Sciences, NCI. In March 2001, the Division of Basic Sciences merged with the Division of Clinical Sciences to form the NCI Center for Cancer Research. In addition to his roles as Chief of GRCBL and Head of the Gene Regulation and Recombination Section, Dr. Strathern was a Deputy Director for the NCI-Center for Cancer Research.
Dr. Strathern retired in 2016 is now an emeritus member of the RNA Biology Laboratory.