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| '''Crystal Structure of a boiling stable protein SP1'''
| | ===Crystal Structure of a boiling stable protein SP1=== |
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| ==Overview==
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| We previously reported on a new boiling stable protein isolated from aspen plants (Populus tremula), which we named SP1. SP1 is a stress-related protein with no significant sequence homology to other stress-related proteins. It is a 108-amino-acid hydrophilic polypeptide with a molecular mass of 12.4 kDa (Wang, W. X., Pelah, D., Alergand, T., Shoseyov, O., and Altman, A. (2002) Plant Physiol. 130, 865-875) and is found in an oligomeric form. Preliminary electron microscopy studies and matrix-assisted laser desorption ionization time-of-flight mass spectrometry experiments showed that SP1 is a dodecamer composed of two stacking hexamers. We performed a SDS-PAGE analysis, a differential scanning calorimetric study, and crystal structure determination to further characterize SP1. SDS-PAGE indicated a spontaneous assembly of SP1 to one stable oligomeric form, a dodecamer. Differential scanning calorimetric showed that SP1 has high thermostability i.e. Tm of 107 degrees C (at pH 7.8). The crystal structure of SP1 was initially determined to 2.4 A resolution by multi-wavelength anomalous dispersion method from a crystal belonging to the space group I422. The phases were extended to 1.8 A resolution using data from a different crystal form (P21). The final refined molecule includes 106 of the 108 residues and 132 water molecules (on average for each chain). The R-free is 20.1%. The crystal structure indicated that the SP1 molecule has a ferredoxin-like fold. Strong interactions between each two molecules create a stable dimer. Six dimers associate to form a ring-like-shaped dodecamer strongly resembling the particle visualized in the electron microscopy studies. No structural similarity was found between the crystal structure of SP1 and the crystal structure of other stress-related proteins such as small heat shock proteins, whose structure has been already determined. This structural study further supports our previous report that SP1 may represent a new family of stress-related proteins with high thermostability and oligomerization.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15371455}}, adds the Publication Abstract to the page |
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| | {{ABSTRACT_PUBMED_15371455}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Sofer, O.]] | | [[Category: Sofer, O.]] |
| [[Category: Plant protein]] | | [[Category: Plant protein]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 10:16:23 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 07:43:24 2008'' |
