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Indiana University Bloomington

Department of Biology

Graduate Studies

Genetics, Cellular & Molecular Sciences Training Grant

Trainee Profile

Rachel Samson

Photo of Rachel Samson
Research Image(s)

acidic hot spring; inset image of Sulfolobus species

Sulfolobus species (inset image) are hyperthermophiles that grow optimally around pH 3 and at temperatures above 75°C. Naturally living in acidic hot springs, such as the one shown in this image, Sulfolobus has intrigued the scientific community due to the remarkable degree of conservation between eukaryotic proteins and those of this organism. Sulfolobus has thus served as a powerful model for dissecting molecular processes such as DNA replication and cell division.

Close-up of Sulfolobus species inset.

Close-up of Sulfolobus species inset.

Graduate Student
Contact Information
By telephone: 812-856-0747 (lab)
SI 410
Bell Lab website
Program
Molecular and Cellular Biochemistry
Education and Training
B.S. Microbiology, 2000, The Ohio State University
Career Development Fellow, 2006, Medical Research Council, Cancer Cell Unit, Cambridge, UK
Research Associate, 2007-2012, Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
Awards
Graduated Magna Cum Laude from Ohio State University, 2000
NIH Genetics, Cellular and Molecular Sciences Training Grant, 2014
Research Description

Duplication of genetic material is essential for all forms of life.  In several species from the archaeal domain of life, DNA replication is initiated in a sequence-specific manner at multiple sites on a single chromosome.  In our studies of the archaeon Sulfolobus islandicus, we find that the three origins or replication are exclusively specified by three distinct initiation factors.  Two of these factors are homologous to the eukaryotic Orc1 and Cdc6 proteins.  The cycle of ATP binding and hydrolysis by at least one of the Orc1/Cdc6 homologs appears to regulate the activity of this protein at its cognate origin locus.  In combination with cell cycle transcriptomic and proteomic studies we have performed, we propose a model whereby ATP hydolysis serves as a simple binary switch to control initiator activity at origins of replication.  This mechanism of control ensures that all origins fire only once in a cell cycle, thus maintaining genome stability.

Select Publications
Samson, R.Y., Xu, Y., Gadelha, C., Stone, T.A., Faqiri, J.N., Li, D., Qin, N., Pu, F., Liang, Y.X., She, Q., Bell, S.D. (2013) Specificity and function of archaeal DNA replication initiator proteins. Cell Rep. 3 (2): 485-496.
Samson, R.Y., Obita, T., Hodgson, B., Shaw, M.K., Chong, P.L., Williams, R.L., Bell, S.D. (2011) Molecular and structural basis of ESCRT-III recruitment to membranes during archaeal cell division. Mol Cell. 41 (2): 186-196.
Samson, R.Y., Obita, T., Freund, S.M., Williams, R.L., Bell, S.D. (2008) A role for the ESCRT system in cell division in archaea. Science. 322 (5908): 1710-1713.
Select Presentations
Recruitment of ESCRT-III during cell division, Archaeal Genetic and Molecular Mechanisms, 2011 (speaker).

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