title: 2.2 A resolution structure of the amino-terminal half of HIV-1 reverse transcriptase (fingers and palm subdomains).
abstract: BACKGROUND
  HIV-1 reverse transcriptase (RT) catalyzes the transformation of single-stranded viral RNA into double-stranded DNA, which is integrated into host cell chromosomes. The molecule is a heterodimer of two subunits, p51 and p66. The amino acid sequence of p51 is identical to the sequence of the amino-terminal subdomains of p66. Earlier crystallographic studies indicate that the RT molecule is flexible, which may explain the difficulty in obtaining high-resolution data for the intact protein. We have therefore determined the structure of a fragment of RT (RT216), which contains only the amino-terminal half of the RT molecule ('finger' and 'palm' subdomains).
  
  
  RESULTS
  The crystal structure of RT216 has been refined at 2.2 A resolution to a crystallographic R-value of 20.8%. The structure is very similar to that of the corresponding part of the p66 subunit in the p66/p51 heterodimer, although there is a small difference in the relative orientation of the two subdomains compared with the structure of an RT-DNA-antibody fragment complex. There are a large number of stabilizing contacts (mainly hydrogen bonds and hydrophobic interactions) between the subdomains. The locations of conserved amino acids and the position of some important drug-resistant mutations are described.
  
  
  CONCLUSIONS
  The RT216 structure provides detailed three-dimensional information of one important part of HIV-1 RT (including the critical active site residues). We propose a model to explain the inhibitory effect of non-nucleoside inhibitors, which partially accounts for their effect in terms of conformational changes of active site residues.
authors.affiliation: Department of Molecular Biology, Uppsala University, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Unge
authors.forename: S
authors.initials: S
authors.lastname: Knight
authors.forename: R
authors.initials: R
authors.lastname: Bhikhabhai
authors.forename: S
authors.initials: S
authors.lastname: Lövgren
authors.forename: Z
authors.initials: Z
authors.lastname: Dauter
authors.forename: K
authors.initials: K
authors.lastname: Wilson
authors.forename: B
authors.initials: B
authors.lastname: Strandberg
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000201:enzymology*; D008958:Models, Molecular; D015394:Molecular Structure; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D010446:Peptide Fragments; D004247:DNA; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase