Preliminary X-ray diffraction studies of the transcriptional inhibitory antibody Fab41.4
J Mazlo1, R L Stanfield, I A Wilson
1Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
Abstract:
The binding of transcription factor ATF-1 to DNA contributes to gene expression and regulation of cell growth. Antibody Mab41.4, raised against ATF-1, and its derivatives Fab41.4 and scFv41.4 inhibit specific DNA binding in vitro and induce apoptotic death of tumor cells in vivo. Structural studies of Fab41.4 were performed to gain insight into the mechanism of action of this potentially therapeutic antibody. The optimal conditions for crystallization of Fab41.4 were determined. Crystals were needle-like in appearance, displayed C2 space-group symmetry and diffracted to a resolution of 1.6 A. The unit-cell parameters were determined to be a = 186.64, b = 40.22, c = 55.58 A, alpha = gamma = 90, beta = 96.93 degrees. The data set was 97.7% complete. Molecular replacement was performed, resulting in an R value of 44.6%.
Insights
Antibody fragments targeting transcription factor ATF-1 inhibit tumor cell growth and DNA binding. Structural studies of Fab41.4 provide insights into its therapeutic mechanism for cancer treatment.
Area of Science:
- Molecular Biology
- Structural Biology
- Immunology
Background:
- Transcription factor activating transcription factor 1 (ATF-1) regulates gene expression and cell growth.
- Antibodies, including Mab41.4 and its derivatives (Fab41.4, scFv41.4), can inhibit ATF-1 DNA binding.
- These antibodies show potential in inducing tumor cell apoptosis.
Purpose of the Study:
- To elucidate the mechanism of action of the antibody fragment Fab41.4.
- To gain structural insights into the interaction between Fab41.4 and ATF-1.
- To assess the therapeutic potential of Fab41.4 in cancer treatment.
Main Methods:
- Optimization of crystallization conditions for Fab41.4.
- X-ray diffraction analysis of Fab41.4 crystals.
- Determination of unit-cell parameters and space-group symmetry.
- Molecular replacement for structural determination.
Main Results:
- Fab41.4 crystals were successfully obtained under optimal conditions.
- Crystals exhibited needle-like morphology and C2 space-group symmetry.
- Diffraction data were collected to a resolution of 1.6 Å, with 97.7% completeness.
- Molecular replacement yielded an R value of 44.6%, indicating successful initial structure determination.
Conclusions:
- Structural studies of Fab41.4 are feasible and provide a basis for understanding its inhibitory mechanism.
- The determined crystal structure offers insights into how Fab41.4 interacts with ATF-1.
- Fab41.4 represents a promising candidate for antibody-based cancer therapeutics targeting ATF-1.
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