Defining the Methyl-Specific Recognition of BRCT Domain Proteins
An important tumor suppressor for preventing carcinogenic mutations with direct roles in DNA repair and transcriptional regulation is a gene known as Breast cancer gene 1(BRCA). These genes have several domains. These domains have important roles in tumor suppression as several pathogenic mutations have been mapped to BRCA1’s C terminal (BRCT). However, there is an emerging paradigm that BRCT domains have binding sites capable of recognizing, additional post-translation modifications (PTM’s) methyl ADP-ribosylation. In understanding the basic mechanism of gene mutation it is important to first understand the details of the novel protein mechanism. e.g. Methyl-dependent recognition has been demonstrated in BRCT domains. Such as BRCA1 and 53 BPI. Similarly Pax transactivation interacting protein 1 (PAXIP1/PTIP) contains tandem BRCT domains that display phosphor-specific recognition with critical roles DNA repair Transcription regulation.BRCA1, 53BP1 and PTIP all share a conserved mode of phosphor-specific recognition, therefore. Therefore the objective of the whole study is to determine if Tandem BRCT domains contain multiple PTM- recognition interfaces. Using-Peptide pull down experiments-we found that similar to BRCA1, PTIP/BRCT56 domain preferentially bind asymmetric dimtheyl-arginine (ADMA) peptides Conducting a mutational analysis with BRCA1, BRCT domain residues that are known to disrupt phosphor-specific intraction and to be pathogeneic(i.e M!&&%R), we observed reduced levels of ADMA-specific binding. Below is a summary of the findings from the Deciphering the mechanistic details of the multiple interaction mediated by BRCT domains will aid our understanding of how aberrant transcriptional growth lead to cancer.
The findings showed that there are several benefits of structural studies and they are basic science in terms of mechanism i.e. enzymes, ion channels, molecular etc.it also showed out role of mutation/ deletion in causing disease, complex formation, insights into the role of proteins as another importance also medical/commercial application i.e. traditional drug design, improve protein stability as a final benefit. In order to fully model the functioning of cell, require atomic level knowledge of the structure of every protein and how they interact with every protein
Project 1 included DNA repairosomes and the problem to be addresses was aggressive forms of breast cancer(BRCA1 deficient) rapidly develop resistance to current therapists. Different types of DNA damage cause different types of lesions, DNA double strand breaks (DSB) are most cytotoxic. When protein molecule is in a crystal, the crystal has two effects on the scattering of the x-rays – the scattering form the single protein molecule is amplified by the number of repeating units (unit cells) in the crystal. Only specific direction is observed in the diffraction pattern. The crystal and x-ray diffraction pattern shows that each spot is referred to as a reflection and is labeled with a value. It continues to show that each reflection has two properties A phase which is related to the position of the atoms in the protein relative to each other. And also amplitude which is related to the number of electrons atoms in the protein molecule. After the data collection, the unit cell dimension and space group are determined. The electron density and resolution diagram show that the further out the reflection go, the more the data can be included into the electron density calculation. This leads to more accurate determination of atoms. Deficies in the DSB repair pathway choices influences tumor genesis.
The conclusion is that BRCA1 plays critical role in error free DNA repair BRCA1 C-terminal (BRCT) domains mediate critical interactions of DNA repair protein complexes. This states that phosphor- protein binding domains involved in protein targeting found in many DNA repai proteins, usually 90-1—amino acids- most commonly found in tandem pairs.2, essential for tumor suppressive function of BRCA1. The conclusion was that mutations that disrupt BRCT domain binding correlate with increased cancer rates.