Characterization of a distinct binding site for the prokaryotic chaperone, GroEL, on a human granulocyte ribonuclease.
Although ribonucleases fold into correct tertiary conformation in vitro guided solely by information contained in the primary amino acid sequence (Sela, M., White, F. H., and Anfinsen, C. B. (1957) Science 124, 691-693), it is not clear whether folding of these proteins proceeds unassisted in a complex intracellular environment. We describe here the specific and high affinity binding of groEL, the prokaryotic homolog of the heat shock protein 60 family of molecular chaperones, to recombinant eosinophil cationic protein and eosinophil-derived neurotoxin, two members of the human ribonuclease gene family. We have determined that groEL binds to a unique peptide sequence near the amino terminus of nascent eosinophil cationic protein that includes the first of eight cysteine residues. This binding site functions independently and can confer groEL binding activity on an unrelated carrier protein. GroEL dissociates from the binding site upon addition of ATP and Mg2+; no other cations or cofactors are necessary. These findings suggest the possibility that interaction with a groEL-like molecular chaperone may be a requirement for correct folding and/or translocation of eukaryotic ribonucleases in vivo.
Rosenberg
H F
HF
Laboratory of Host Defenses, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Ackerman
S J
SJ
Tenen
D G
DG
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism; D018834:Chaperonin 60; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000378:metabolism; D004926:Escherichia coli; D006098:Granulocytes / Q000201:enzymology*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases / Q000737:chemistry / Q000378:metabolism*
D001426:Bacterial Proteins; D001798:Blood Proteins; D018834:Chaperonin 60; D047091:Eosinophil Granule Proteins; D006360:Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; D012260:Ribonucleases