Binding of elongin A or a von Hippel-Lindau peptide stabilizes the structure of yeast elongin C.
Elongin is a heterotrimeric transcription elongation factor composed of subunits A, B, and C in mammals. Elongin A and C are F-box-containing and SKP1 homologue proteins, respectively, and are therefore of interest for their potential roles in cell cycle-dependent proteolysis. Mammalian elongin C interacts with both elongin A and elongin B, as well as with the von Hippel-Lindau tumor suppressor protein VHL. To investigate the corresponding interactions in yeast, we have utilized NMR spectroscopy combined with ultracentrifugal sedimentation experiments to examine complexes of yeast elongin C (Elc1) with yeast elongin A (Ela1) and two peptides from homologous regions of Ela1 and human VHL. Elc1 alone is a homotetramer composed of subunits with a structured N-terminal region and a dynamically unstable C-terminal region. Binding of a peptide fragment of the Elc1-interaction domain of Ela1 or with a homologous peptide from VHL promotes folding of the C-terminal region of Elc1 into two regular helical structures and dissociates Elc1 into homodimers. Moreover, analysis of the complex of Elc1 with the full Elc1-interaction domain of Ela1 reveals that the Elc1 homodimer is dissociated to preferentially form an Ela1/Elc1 heterodimer. Thus, elongin C is found to oligomerize in solution and to undergo significant structural rearrangements upon binding of two different partner proteins. These results suggest a structural basis for the interaction of an F-box-containing protein with a SKP1 homologue and the modulation of this interaction by the tumor suppressor VHL.
Botuyan
M V
MV
Division of Molecular and Structural Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON, Canada M5G 2M9.
Koth
C M
CM
Mer
G
G
Chakrabartty
A
A
Conaway
J W
JW
Conaway
R C
RC
Edwards
A M
AM
Arrowsmith
C H
CH
Chazin
W J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D000075065:Elongin; D016147:Genes, Tumor Suppressor; D006801:Humans; D006860:Hydrogen Bonding; D008025:Ligases; D046911:Macromolecular Substances; D008322:Mammals; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D014461:Ultracentrifugation; D051794:Von Hippel-Lindau Tumor Suppressor Protein
C000616397:ELOA protein, human; C000616396:ELOB protein, human; C000616395:ELOC protein, human; C000616404:Eloa protein, rat; C000616402:Elob protein, rat; C000616400:Eloc protein, rat; D000075065:Elongin; D046911:Macromolecular Substances; D011506:Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D008025:Ligases; C497446:VHL protein, human