Low-resolution structure of Drosophila translin

Area of Science:

• Structural biology
• Biochemistry
• X-ray crystallography

Background:

• Translin is a protein found in Drosophila melanogaster.
• Previous studies suggested translin might form a decamer.
• Understanding the oligomeric state is crucial for function.

Purpose of the Study:

• To determine the quaternary structure of Drosophila melanogaster translin.
• To investigate the effect of reductive methylation on crystal quality and DNA-binding.
• To utilize low-resolution X-ray crystallography for structural elucidation.

Main Methods:

• X-ray diffraction of native and reductively methylated Drosophila translin crystals.
• Size-exclusion chromatography to analyze protein behavior.
• Molecular replacement method for crystal structure solution.
• Refinement of the crystal structure to R work (R free) of 0.24 (0.29).

Main Results:

• Reductive methylation improved crystal quality, enabling diffraction to 4.2 Å resolution.
• The crystal structure revealed Drosophila translin exists as an octamer, contradicting decamer predictions from gel filtration.
• The octameric structure shares a similar quaternary fold with orthologs, suggesting an up-down dimer as a subunit.
• Asymmetric assembly and increased radius of gyration explain differences in gel filtration profiles between human and Drosophila proteins.

Conclusions:

• Low-resolution X-ray crystallography is effective for studying complex biological oligomers.
• The octameric structure of Drosophila translin provides new insights into its assembly and function.
• Structural data clarifies discrepancies between biochemical assays and predicted oligomeric states.