Abstract
SMT3 (Suppressor of MIF2 3 protein) was identified as a mutation
suppressor in yeast centromere protein MIF2. It is also known as an
ubiquitin-like protein due to the smilarities of their primary structures that
is very conserved during the eukaryotic evolution. Although only one
SMT3 was found in low eukaryotes such as in yeast, three members of
SMT3 (SMT3A, SMT3B and SMT3C) have been identified in high
eukaryotes. It has been known that SMT3C plays an important role in post-translational modification. However, the functions of SMT3A and SMT3B are not well studied yet and the relationship among the SMT3 families remains unclear.
In the present study, Daxx, a Fas binding protein, was demonstrated to bind to SMT3B using yeast two-hybrid assay. It was found that the
N-terminal domain of Daxx (Daxx 1) and the C-terminal domain of Daxx
(Daxx 4), respecifitively, bound to all members of human SMT3
families (including SMT3A, SMT3B and SMT3C). Neverthless,
mechanisms of interactions between the SMT3 families and Daxx
domains remined unclear. Studies on truncated human SMT3 families
have shown that two glycines on the C-terminal end of human SMT3
families were required in the interaction between SMT3 and Daxx
domains, for example, SMT3A and SMT3B required C-terminal two glycines on the Daxx 4 domain where as SMT3C required C-terminal two glycines on the Daxx 1 domain. Morever, truncated SMT3C and Daxx 1 domain point mutations have also indicated that the the linkage of
glycine97 of SMT3C and the lysine60 of Daxx 1, in which the SMT3C/
SUMO-1 consensus sequence £ZKXE was found. Further, SMT3C was
the only member of the SMT3 families capable of self-reacting.
Results also suggested that similar mechanism of interaction
between SMT3A/B and Daxx 1, which is not in accordance with the model proposed in this study regarding the interaction mechanism between SMT3C and Daxx 1. Although two glycines on the C-terminal end of SMT3A/B were necessary for the interactions with Daxx 4 domains, the SMT3C/SUMO-1-consensus sequence £ZKXE was not detected in the Daxx 4 domain. It is therefore, suggested that the mechanism of the interaction between SMT3A/B and Daxx 4 is similar to that of SMT3C and Daxx 1, that may required different binding sequences that is specific for SMT3A/B.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0727101-153531 |
| Date | 27 July 2001 |
| Creators | Chou, Yu-Huai |
| Contributors | none, none, none |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0727101-153531 |
| Rights | unrestricted, Copyright information available at source archive |
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