Retroviral nucleocapsid protein-metal ion interactions: folding and sequence variants.
Retroviral nucleocapsid proteins contain one or two proposed metal-binding sequences of the form Cys-Xaa2-Cys-Xaa4-His-Xaa4-Cys. Previously, we reported that an 18-amino acid peptide derived from the nucleocapsid protein of Rauscher murine leukemia virus (RMLV) binds metals such as Co2+ and Zn2+. We have now synthesized the entire nucleocapsid protein from RMLV. We report here that the protein also binds Co2+ and Zn2+ and does so with a higher affinity than does the peptide. Limited proteolysis and circular dichroism studies reveal that metal binding induces folding of the metal-binding domain and, perhaps, the regions adjacent to it but the remainder of the protein remains in a relatively unstructured state. In addition, we have synthesized sequence variants of the metal-binding domain that correspond to viral mutations reported in the literature. In many cases, the metal-binding properties of these peptides correlate with the observed biological activity, providing further evidence for the importance of metal binding to nucleocapsid function.
Green
L M
LM
Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218.
Berg
J M
JM
D000595:Amino Acid Sequence; D001665:Binding Sites; D002213:Capsid / Q000138:chemical synthesis / Q000235:genetics* / Q000378:metabolism; D002942:Circular Dichroism; D003035:Cobalt / Q000378:metabolism*; D014644:Genetic Variation; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis; D011487:Protein Conformation; D011925:Rauscher Virus / Q000235:genetics*; D013053:Spectrophotometry; D014758:Viral Core Proteins / Q000138:chemical synthesis / Q000235:genetics* / Q000378:metabolism
D010455:Peptides; D014758:Viral Core Proteins; D003035:Cobalt