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Three-dimensional structure of a barnase-3'GMP complex at 2.2A resolution
V Guillet1, A Lapthorn, Y Mauguen
1Laboratoire de Physique, CNRS, UPR180, Centre d'Etudes Pharmaceutiques, Chatenay-Malabry, France.
FEBS Letters
|September 13, 1993
Summary
Barnase enzyme structure reveals a productive binding mode for 3'-guanylic acid. This X-ray crystallography study clarifies the enzyme-nucleotide interaction crucial for catalytic mechanisms.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Barnase is a ribonuclease enzyme.
- Understanding its interaction with nucleotides is key to elucidating its catalytic mechanism.
Purpose of the Study:
- To determine the X-ray crystal structure of barnase co-crystallized with 3 -guanylic acid.
- To analyze the binding mode and its implications for the catalytic mechanism.
Main Methods:
- Co-crystallization of barnase with 3 -guanylic acid at neutral pH.
- X-ray structure determination using molecular replacement.
- Refinement of the crystal structure to a final R-factor of 18.7%.
Main Results:
- The protein folding of barnase remained consistent with its native form.
- The nucleotide binding site showed high similarity to the homologous binase-3 GMP complex.
- A productive binding mode was observed, featuring a syn glycosyl torsion angle enabling Glu73 interaction with the nucleotide's 2 O.
Conclusions:
- The determined structure provides insights into barnase's substrate binding and catalytic mechanism.
- The binding mode supports the classical catalytic mechanism involving Glu73.
- The dimeric arrangement and nucleotide positioning offer clues about RNA-enzyme interactions.