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Bi-directional SIFT predicts a subset of activating mutations
William Lee1, Yan Zhang, Kiran Mukhyala
1Department of Bioinformatics, Genentech, Inc., South San Francisco, California, United States of America.
Plos One
|December 17, 2009
Summary
A new tool, bi-directional SIFT (B-SIFT), identifies activating mutations. This computational method aids in understanding protein function and discovering cancer-driving mutations.
Area of Science:
- Genomics
- Bioinformatics
- Computational Biology
Background:
- High-throughput sequencing generates vast amounts of genetic variation data.
- Identifying functional mutations, especially those causing hyperactivation or gain-of-function, is crucial but challenging.
- Existing computational tools lack specificity for gain-of-function mutation prediction.
Purpose of the Study:
- To develop a computational tool for identifying gain-of-function mutations.
- To adapt the Sorting Intolerant from Tolerant (SIFT) algorithm for enhanced functional prediction.
- To analyze large-scale cancer genotyping data for potential activating mutations.
Main Methods:
- Modified the SIFT algorithm to create bi-directional SIFT (B-SIFT).
- Utilized protein sequence alignments with homologous sequences to assess evolutionary fitness.
- Applied B-SIFT to experimental datasets and cancer genotyping data.
Main Results:
- B-SIFT successfully identified experimentally verified activating mutants.
- Analysis of cancer data revealed potential activating mutations.
- Structural evidence was provided for some identified mutations.
Conclusions:
- B-SIFT is effective in identifying gain-of-function mutations.
- The tool can aid in protein engineering and cancer mutation discovery.
- B-SIFT offers a valuable approach for functional mutation analysis.
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Spontaneous mutations arise infrequently during DNA replication due to errors in the process. A key factor behind these errors is tautomeric shifts in nitrogenous bases, where bases transition from keto to enol forms or amino to imino forms. This shift can alter base-pairing rules, leading to mutations. Additionally, reactive oxygen species (ROS) arising from aerobic metabolism can damage DNA, resulting in depurination (loss of a purine base) or depyrimidination (loss of a pyrimidine base).
Point and Frameshift Mutations
Point mutations are genetic alterations involving the change of a single nucleotide base pair in DNA. Depending on how the alteration affects protein synthesis, they can lead to various consequences.Point mutations fall into the following types:Silent mutations occur when a nucleotide change does not alter the amino acid sequence due to the redundancy of the genetic code. For instance, changing ACC to ACA still encodes threonine, leaving the protein function unaffected. This occurs because...

