Yeast tRNA(Asp)-aspartyl-tRNA synthetase complex: low resolution crystal structure.

Area of Science:

• Structural Biology
• Biochemistry
• Molecular Genetics

Background:

• Yeast aspartyl-tRNA synthetase (AspRS) is crucial for protein synthesis, catalyzing the attachment of aspartic acid to its cognate transfer RNA (tRNA).
• Understanding the structural basis of this aminoacylation reaction requires detailed knowledge of the AspRS-tRNA complex.

Purpose of the Study:

• To determine the low-resolution crystal structure of the yeast aspartyl-tRNA synthetase complex.
• To visualize the arrangement of the protein and tRNA molecules within the crystal.

Main Methods:

• Cocrystallization of yeast aspartyl-tRNA synthetase with its cognate tRNA.
• Low-resolution structure determination using neutron and X-ray diffraction.
• Neutron contrast variation with varying D2O content to distinguish protein and tRNA.
• Structure refinement using X-ray diffraction data and density modification.

Main Results:

• The crystal structure of the aspartyl-tRNA synthetase-tRNA complex was solved to 10 Å resolution in the cubic space group I432.
• Neutron diffraction identified the synthetase at 40 Å and tRNA molecules at 20 Å resolution.
• The refined model is consistent with solution-based chemical probing data.

Conclusions:

• The study provides a low-resolution structural model of the yeast aspartyl-tRNA synthetase-tRNA complex.
• The structural data supports current models of tRNA recognition and binding by aminoacyl-tRNA synthetases.
• This work demonstrates the utility of neutron contrast variation for phasing and structure determination of macromolecular complexes.