Aspen SP1, an exceptional thermal, protease and detergent-resistant self-assembled nano-particle

Wang Xia Wang, Or Dgany, Sharon Grayer Wolf, Ilan Levy, Rachel Algom, Yehonathan Pouny, Amnon Wolf, Ira Marton, Arie Altman, Oded Shoseyov*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Stable protein 1 (SP1) is a homo-oligomeric protein isolated from aspen (Populus tremula aspen) plants which forms a ring-shape dodecameric particle with a central cavity. The oligomeric form of SP1 is an exceptionally stable structure that is resistant to proteases (e.g., trypsin, V8, and proteinase K), high temperatures, organic solvents, and high levels of ionic detergent. Analytical ultra-centrifugation, chemical cross-linking, matrix-assisted laser-desorption time-of-flight mass spectrometry (MALDI-TOF-MS), and transmission electron microscopy were used to further characterize the SP1 dodecamer. Introduction of a single cysteine at the N-terminus of SP1 enabled the formation of disulfide bridges within the SP1 dodecamer, concurrent with increased melting point. A six-histidine tag was introduced at the N-terminus of SP1 to generate 6HSP1, and the ΔNSP1 mutant was generated by a deletion of amino acids 2-6 at the N-terminus. Both 6HSP1 and ΔNSP1 maintained their ability to assemble a stable dodecamer. Remarkably, these SP1 homo-dodecamers were able to re-assemble into stable hetero-dodecamers following co-electro-elution from SDS-PAGE. The exceptional stability of the SP1-nano ring and its ability to self-assemble hetero-complexes paves the way to further research in utilizing this unique protein in nano-biotechnology.

Original languageAmerican English
Pages (from-to)161-168
Number of pages8
JournalBiotechnology and Bioengineering
Issue number1
StatePublished - 5 Sep 2006


  • Nanoparticle
  • Oligomer
  • Self-assembly
  • Stable
  • Tremula


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