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Total sequence decomposition distinguishes functional modules, "molegos" in apurinic/apyrimidinic endonucleases
Catherine H Schein1, Numan Ozgün, Tadahide Izumi
1Sealy Center for Structural Biology, Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston TX 77555-1157, USA. cathy@newton.utmb.edu
BMC Bioinformatics
|November 26, 2002
Summary
This study introduces a modular approach using molecular legos (molegos) to analyze DNA repair enzymes. This method enhances protein alignment and reveals key residues controlling enzymatic specificity.
Area of Science:
- Biochemistry
- Structural Biology
- Bioinformatics
Background:
- The apurinic/apyrimidinic endonuclease (APE) superfamily, including DNase-1 and inositol 5 -polyphosphate phosphatases (IPP), are crucial for DNA repair.
- These enzymes catalyze metal ion-dependent phosphorolysis but act on distinct substrates.
- Understanding their conserved structural motifs is key to deciphering their functions.
Purpose of the Study:
- To apply a sequence decomposition method using the MASIA tool to analyze APE DNA repair proteins.
- To identify and structurally annotate conserved motifs (molegos) within the APE family and related proteins.
- To investigate how these molegos contribute to substrate specificity and enzymatic activity.
Main Methods:
- Utilized the web-based MASIA tool for total sequence decomposition of APE proteins.
- Structurally annotated conserved sequence motifs, termed molegos.
- Improved sequence alignment by focusing on conserved residues at molego boundaries.
Main Results:
- Identified 12 sequence motifs in APEs, with 10 designated as structurally conserved molegos.
- All essential DNA cleavage residues in APEs were included within these motifs.
- Five molegos were found to be conserved across APEs, DNase-1, and IPP families, improving structural alignment.
- Distinct APE molegos, not directly involved in cleavage, mediate protein-DNA interactions, enhancing DNA binding and processivity.
Conclusions:
- A modular, molego-based approach refines structurally predictive alignments for homologous proteins with low sequence identity.
- This method uncovers residues outside the active site that are critical for controlling enzymatic specificity.
- The findings provide insights into the functional diversification within the APE superfamily.