N‐Terminal domain of HTLV‐I integrase. Complexation and conformational studies of the zinc finger

Abstract
The HTLV‐I integrase N‐terminal domain [50‐residue peptide (IN50)], and a 35‐residue truncated peptide formed by residues 9–43 (IN35) have been synthesized by solid‐phase peptide synthesis. Formation of the 50‐residue zinc finger type structure through a HHCC motif has been proved by UV‐visible absorption spectroscopy. Its stability was demonstrated by an original method using RP‐HPLC. Similar experiments performed on the 35‐residue peptide showed that the truncation does not prevent zinc complex formation but rather that it significantly influences its stability. As evidenced by CD spectroscopy, the 50‐residue zinc finger is unordered in aqueous solution but adopts a partially helical conformation when trifluoroethanol is added. These results are in agreement with our secondary structure predictions and demonstrate that the HTLV‐I integrase N‐terminal domain is likely to be composed of an helical region (residues 28–42) and a β‐strand (residues 20–23), associated with a HHCC zinc‐binding motif. Size‐exclusion chromatography showed that the structured zinc finger dimerizes through the helical region. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.

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