| Autor: |
Kappé, Guido, Aquilina, J. Andrew, Wunderink, Lisa, Kamps, Bram, Robinson, Carol V., Garate, Teresa, Boelens, Wilbert C., de Jong, Wilfried W. |
| Zdroj: |
Proteins; Oct2004, Vol. 57 Issue 1, p109-117, 9p |
| Abstrakt: |
Small heat shock proteins (sHSPs), which range in monomer size between 12 and 42 kDa, are characterized by a conserved C-terminal α-crystallin domain of 80-100 residues. They generally form large homo- or heteromeric complexes, and typically have in vitro chaperone-like activity, keeping unfolding proteins in solution. A special type of sHSP, with a duplicated α-crystallin domain, is present in parasitic flatworms (Platyhelminthes). Considering that an α-crystallin domain is essential for the oligomerization and chaperone-like properties of sHSPs, we characterized Tsp36 from the tapeworm Taenia saginata. Both wild-type Tsp36 and a mutant (Tsp36C→R) in which the single cysteine has been replaced by arginine were expressed and purified. Far-UV CD measurements of Tsp36 were in agreement with secondary structure predictions, which indicated α-helical structure in the N-terminal region and the expected β-sandwich structure for the two α-crystallin domains. Gel permeation chromatography and nano-ESI-MS showed that wild type Tsp36 forms dimers in a reducing environment, and tetramers in a non-reducing environment. The tetramers are stabilized by disulfide bridges involving a large proportion of the Tsp36 monomers. Tsp36C→R exclusively occurs as dimers according to gel permeation chromatography, while the nondisulfide bonded fraction of wild type Tsp36 dissociates from tetramers into dimers under nonreducing conditions at increased temperature (43°C). The tetrameric form of Tsp36 has a greater chaperone-like activity than the dimeric form. Proteins 2004. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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