PUBLICATION
Ubc9 interacts with a nuclear localization signal and mediates nuclear localization of the paired-like homeobox protein Vsx-1 independent of SUMO-1 modification
- Authors
- Kurtzman, A.L. and Schechter, N.
- ID
- ZDB-PUB-010511-8
- Date
- 2001
- Source
- Proceedings of the National Academy of Sciences of the United States of America 98(10): 5602-5607 (Journal)
- Registered Authors
- Kurtzman, Aaron, Schechter, Nisson
- Keywords
- none
- MeSH Terms
-
- Amino Acid Sequence
- Animals
- COS Cells
- Cell Nucleus/metabolism
- Eye Proteins/chemistry
- Eye Proteins/metabolism*
- Homeodomain Proteins/chemistry
- Homeodomain Proteins/metabolism*
- Humans
- Ligases/metabolism*
- Molecular Sequence Data
- Nuclear Localization Signals*
- SUMO-1 Protein
- Sequence Homology, Amino Acid
- Ubiquitin-Conjugating Enzymes*
- Ubiquitins/metabolism*
- PubMed
- 11331779 Full text @ Proc. Natl. Acad. Sci. USA
Citation
Kurtzman, A.L. and Schechter, N. (2001) Ubc9 interacts with a nuclear localization signal and mediates nuclear localization of the paired-like homeobox protein Vsx-1 independent of SUMO-1 modification. Proceedings of the National Academy of Sciences of the United States of America. 98(10):5602-5607.
Abstract
Vsx-1 is a paired-like:CVC homeobox gene whose expression is linked to bipolar cell differentiation during zebrafish retinogenesis. We used a yeast two-hybrid screen to identify proteins interacting with Vsx-1 and isolated Ubc9, an enzyme that conjugates the small ubiquitin-like modifier SUMO-1. Despite its interaction with Ubc9, we show that Vsx-1 is not a substrate for SUMO-1 in COS-7 cells or in vitro. When a yeast two-hybrid assay is used, deletion analysis of the interacting domain on Vsx-1 shows that Ubc9 binds to a nuclear localization signal (NLS) at the NH(2) terminus of the homeodomain. In SW13 cells, Vsx-1 localizes to the nucleus and is excluded from nucleoli. Deletion of the NLS disrupts this nuclear localization, resulting in a diffuse cytoplasmic distribution of Vsx-1. In SW13 AK1 cells that express low levels of endogenous Ubc9, Vsx-1 accumulates in a perinuclear ring and colocalizes with an endoplasmic reticulum marker. However, NLS-tagged STAT1 protein exhibits normal nuclear localization in both SW13 and SW13 AK1 cells, suggesting that nuclear import is not globally disrupted. Cotransfection of Vsx-1 with Ubc9 restores Vsx-1 nuclear localization in SW3 AK1 cells and demonstrates that Ubc9 is required for the nuclear localization of Vsx-1. Ubc9 continues to restore nuclear localization even after a C93S active site mutation has eliminated its SUMO-1-conjugating ability. These results suggest that Ubc9 mediates the nuclear localization of Vsx-1, and possibly other proteins, through a nonenzymatic mechanism that is independent of SUMO-1 conjugation.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping