In its bloodstream form (BF), Trypanosoma brucei escapes elimination by its host's immune response by periodically switching its variant surface glycoprotein (VSG). Although there are many VSG genes, only the VSG positioned at an active expression site (ES) is transcribed. When T. brucei returns to its tsetse vector, it differentiates into a non-infective, procyclic form (PF), and all ESs are inactivated. The mechanisms of ES inactivation in BF and PF are not understood but appear to be distinct. Studies from a variety of organisms indicate that core and variant histones often play important roles in the control of transcription and development. Recently, two genes from T. brucei that encode distinct histone variants were identified and the experiments outlined in this proposal explore how they may affect the transcriptional control of ESs. Upon establishing that both variants are likely to exist in nucleosomes in vivo, mutant alleles of each will be introduced into both BF and PF cells and tested for their ability to perturb the silencing of VSG and reporter genes at inactive ESs. Additionally, to determine if either variant is present at unique sites within the nucleus, immunofluorescence microscopy and chromatin immunoprecipitations (ChrIP) will be performed. Finally, to examine if the chemical modifications of histones differ between active and inactive ESs, chromatin purified from both BF and PF cells will be analyzed by mass spectroscopy and by ChrIP.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32AI010380-03
Application #
6532648
Study Section
Special Emphasis Panel (ZRG1-TMP (01))
Program Officer
Rogers, Martin J
Project Start
2002-08-01
Project End
Budget Start
2002-08-01
Budget End
2003-07-31
Support Year
3
Fiscal Year
2002
Total Cost
$48,148
Indirect Cost
Name
Rockefeller University
Department
Public Health & Prev Medicine
Type
Other Domestic Higher Education
DUNS #
071037113
City
New York
State
NY
Country
United States
Zip Code
10065