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Crystallographic studies on E. coli Trp aporepressor
1Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland.
Acta Biochimica Polonica
|January 1, 1989
Summary
Two crystal forms of Trp aporepressor were obtained for high-resolution X-ray diffraction analysis. These findings provide insights into the inactive Trp repressor structure.
Area of Science:
- Structural Biology
- Biochemistry
- Molecular Biology
Background:
- The Trp repressor regulates tryptophan biosynthesis in bacteria.
- Understanding the structure of the inactive Trp aporepressor is crucial for elucidating its regulatory mechanism.
Purpose of the Study:
- To obtain and characterize crystal forms of Trp aporepressor suitable for high-resolution X-ray diffraction.
- To provide structural insights into the unliganded state of the Trp repressor.
Main Methods:
- Crystallization of Trp aporepressor.
- X-ray diffraction analysis of obtained crystal forms.
Main Results:
- Two crystal forms of Trp aporepressor were successfully obtained: orthorhombic (P 2(1)2(1)2) diffracting to 1.8 A and tetragonal (P 4(1) or P 4(3)) diffracting to 2.4 A.
- The orthorhombic crystals contain one monomer per asymmetric unit, with a twofold axis relating dimer subunits.
- The tetragonal crystals contain two dimers per asymmetric unit and are nearly isomorphous to previously studied Trp repressor and pseudorepressor crystals.
Conclusions:
- The obtained crystal forms of Trp aporepressor are suitable for high-resolution structural studies.
- These structures will aid in understanding the conformational changes associated with Trp repressor activation and repression.