Abstract
Background: Integrase mediates a crucial step in the life cycle of the human immunodeficiency virus (HIV). The enzyme cleaves the vital DNA ends in a sequence-dependent manner and couples the newly generated hydroxyl groups to phosphates in the target DNA. Three domains have been identified in HIV integrase: an amino-terminal domain, a central catalytic core end a carboxy-terminal DNA-binding domain. The amino-terminal region is the only domain with unknown structure thus far. This domain, which is known to bind zinc contains a HHCC motif that is conserved in retroviral integrases. Although the exact function of this domain is unknown, it is required for cleavage and integration. Results: The three-dimensional structure of the amino-terminal domain of HIV-2 integrase has been determined using two-dimensional and three-dimensional nuclear magnetic resonance data. We obtained 20 final structures calculated using 693 nuclear Overhauser effects, which display a backbone root-mean square deviation versus the average of 0.25 Å for the well defined region. The structure consists of three α helices and a helical turn. The zinc is coordinated with his 12 via the N(ε2) atom with His 16 via the N(δ1) atom and with the sulfur atoms of Cys40 and Cys43. The α helices form a three-helix bundle that is stabilized by this zinc-binding unit. The helical arrangement is similar to that found in the DNA-binding domains of the trp repressor, the prd paired domain and Tc3A transposase. Conclusion: The amino-terminal domain of HIV-2 integrase nasa remarkable hybrid structure combining features of a three-helix bundle fold with a zinc-binding HHCC motif. This structure shows no similarity with any of the known zinc-finger structures. The strictly conserved residues of the HHCC motif of retroviral integrases are involved in metal coordination, whereas many other well conserved hydrophobic residues are part of the protein core.
Original language | English |
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Pages (from-to) | 739-746 |
Number of pages | 8 |
Journal | Current Biology |
Volume | 7 |
Issue number | 10 |
Publication status | Published - 1997 |
Keywords
- chloride
- cysteine
- DNA
- histidine
- hybrid protein
- integrase
- zinc
- zinc chloride
- zinc derivative
- amino acid sequence
- animal
- article
- binding site
- chemical structure
- chemistry
- drug effect
- enzyme stability
- human
- metabolism
- molecular genetics
- nuclear magnetic resonance spectroscopy
- protein conformation
- protein folding
- solution and solubility