Trypanosomatid parasites cause devastating and life-threatening human diseases including African Sleeping Sickness, Chagas disease and Leishmaniasis. Current drug treatments are inadequate, often toxic, and no vaccines are available. With several biological properties being pursued as potential drug targets for much needed parasite-selective chemotherapeutic interventions, nuclear DNA replication has been historically overlooked presumably because it was assumed that the replication machinery was going to be conserved among eukaryotes. Post-genome sequencing, we now know that several aspects of DNA replication initiation and regulation are divergent or completely lacking in trypanosomatids, and that there are fewer replication origins than in other model eukaryotes. However, the machinery for replication fork progression, and how fork progression is regulated in the context of large polycistronic transcription units is poorly understood. There are many layers of regulation governing DNA replication to ensure that genetic information is accurately transmitted to progeny cells, and the recent links to antigenic variation in Trypanosoma brucei suggest additional layers of regulation are likely. The identification of factors necessary that promote replication fork progression and stability is likely to uncover fundamental processes necessary to maintain genome stability, and trypanosome-specific factors that might serve as selective drug targets. Here we propose to adapt an innovative methodology called iPOND (isolation of proteins on nascent DNA) to study DNA replication in T. brucei, an extracellular pathogen with well-established genetic tools.
Aim 1 of this proposal will identify a comprehensive list of the DNA replication machinery (and associated regulatory factors) by coupling iPOND with mass spectrometry. Additionally, we will acquire temporal information about chromatin deposition and maturation by comparing protein profiles obtained under brief label conditions (pulse) vs. pulse-chase conditions.
Aim 2 will assess changes in the protein profile under replication stress conditions to identify the trypanosomatid replication restart machinery. Together these studies will provide crucial information about trypanosome-specific factors required for DNA replication, a process conserved in all trypanosomatids, and interesting new insights into the diverse mechanisms by which eukaryotes accomplish a fundamental mechanism such as DNA synthesis. Additionally, successful completion of this proposed work will generate new insights into proteins that function at the crossroads of transcription, chromatin remodeling and DNA replication.

Public Health Relevance

The parasite Trypanosoma brucei causes fatal human African trypanosomiasis (sleeping sickness) and drugs to treat the disease are toxic with resistance emerging. Germinal studies on DNA replication indicate portions of the trypanosome machinery are divergent from other eukaryotes. This project will apply a new technology based on purification of protein cross- linked to nascent DNA to identify a comprehensive set of DNA replication proteins some of which are likely to be parasite-specific, thereby providing highly selective candidate drug targets for African trypanosomes and likely for other kinetoplastid parasites as well.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI126455-01
Application #
9172587
Study Section
Pathogenic Eukaryotes Study Section (PTHE)
Program Officer
Joy, Deirdre A
Project Start
2016-06-01
Project End
2018-05-31
Budget Start
2016-06-01
Budget End
2017-05-31
Support Year
1
Fiscal Year
2016
Total Cost
$222,992
Indirect Cost
$72,992
Name
University of Massachusetts Amherst
Department
Microbiology/Immun/Virology
Type
Schools of Earth Sciences/Natur
DUNS #
153926712
City
Amherst
State
MA
Country
United States
Zip Code
01003
Rocha-Granados, Maria C; Klingbeil, Michele M (2016) Leishmania DNA Replication Timing: A Stochastic Event? Trends Parasitol 32:755-757