Aggregation of truncated GST-HD exon 1 fusion proteins containing normal range and expanded glutamine repeats.
We have shown previously by electron microscopy that the purified glutathione S-transferase (GST)-Huntington's disease (HD) exon 1 fusion protein with 51 glutamine residues (GST-HD51) is an oligomer, and that site-specific proteolytic cleavage of this fusion protein results in the formation of insoluble more highly ordered protein aggregates with a fibrillar or ribbon-like morphology (E. Scherzinger et al. (1997) Cell 90, 549-558). Here we report that a truncated GST HD exon 1 fusion protein with 51 glutamine residues, which lacks the proline-rich region C-terminal to the polyglutamine (polyQ) tract (GST-HD51 delta P) self-aggregates into high-molecular-mass protein aggregates without prior proteolytic cleavage. Electron micrographs of these protein aggregates revealed thread-like fibrils with a uniform diameter of ca. 25 nm. In contrast, proteolytic cleavage of GST-HD51 delta P resulted in the formation of numerous clusters of high-molecular-mass fibrils with a different, ribbon-like morphology. These structures were reminiscent of prion rods and beta-amyloid fibrils in Alzheimer's disease. In agreement with our previous results with full-length GST-HD exon 1, the truncated fusion proteins GST-HD20 delta P and GST-HD30 delta P did not show any tendency to form more highly ordered structures, either with or without protease treatment.
Hollenbach
B
B
Max-Planck-Institut für Molekulare Genetik, Berlin, Germany.
Scherzinger
E
E
Schweiger
K
K
Lurz
R
R
Lehrach
H
H
Wanker
E E
EE
D003001:Cloning, Molecular; D004926:Escherichia coli; D005091:Exons; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D017384:Sequence Deletion; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*
C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase