Covalent attachment of ubiquitin, either as a monomer or as a polymer (polyubiquitin chains), serves as a signal that regulates the location, activity and/or degradation of many proteins. After serving as a signal polyubiquitin must be processed to monoubiquitin to maintain ubiquitin homeostasis. Isopeptidase T (IsoT) is a specialized deubiquitinating enzyme responsible for the regeneration of monoubiquitin from polyubiquitin chains. This role makes IsoT a central regulator of the ubiquitin system. The goal of this proposal is to understand how IsoT binds multiple isoforms of polyubiquitin chains by: 1) testing the polyubiquitin chain isoform binding selectivity of Isot; 2) determining how each of the four ubiquitin binding domains of IsoT contributes to the recognition of polyubiquitin chains; and 3) obtaining a molecular description of the recognition of polyubiquitin chains by IsoT using X-ray crystallography. Determining the substrate preference of IsoT and which domains are involved in binding each polyubiquitin chain isoform will provide insight into the general mechanism of polyubiquitin chain recognition and may aid in the development of pharmacological effectors of the ubiquitin system.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31GM075426-03
Application #
7283120
Study Section
Special Emphasis Panel (ZRG1-F08 (29))
Program Officer
Gaillard, Shawn R
Project Start
2005-09-01
Project End
2008-05-12
Budget Start
2007-09-01
Budget End
2008-05-12
Support Year
3
Fiscal Year
2007
Total Cost
$21,833
Indirect Cost
Name
Emory University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Komander, David; Reyes-Turcu, Francisca; Licchesi, Julien D F et al. (2009) Molecular discrimination of structurally equivalent Lys 63-linked and linear polyubiquitin chains. EMBO Rep 10:466-73
Reyes-Turcu, Francisca E; Shanks, John R; Komander, David et al. (2008) Recognition of polyubiquitin isoforms by the multiple ubiquitin binding modules of isopeptidase T. J Biol Chem 283:19581-92
Reyes-Turcu, Francisca E; Horton, John R; Mullally, James E et al. (2006) The ubiquitin binding domain ZnF UBP recognizes the C-terminal diglycine motif of unanchored ubiquitin. Cell 124:1197-208