What is Recombinational DNA repair?
Recombination repair is a mechanism for generating a functional DNA molecule from two damaged molecules. It is an essential repair process for dividing cells because a replication fork may arrive at a damaged site, such as a thymine dimer, before the excision repair system has eliminated damage.
What is Nhej in DNA repair?
Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. NHEJ is referred to as “non-homologous” because the break ends are directly ligated without the need for a homologous template, in contrast to homology directed repair, which requires a homologous sequence to guide repair.
What is Alt Nhej?
Alternative NHEJ (alt-NHEJ) refers to more recently described mechanism(s) that repair DSBs in less-efficient backup reactions. There is great interest in defining alt-NHEJ more precisely, including its regulation relative to c-NHEJ, in light of evidence that alt-NHEJ can execute chromosome rearrangements.
What mechanisms can repair DNA?
There are two main mechanisms for repairing double strand breaks: homologous recombination and classical nonhomologous end joining. Homologous recombination involves the exchange of nucleotide sequences to repair damaged bases on both strands of DNA through the utilization of a sister chromatid.
How does homologous recombination repair DNA?
To allow homologous recombination (HR) DNA repair, the chromatin must be remodeled. In eukaryotes, ATP dependent chromatin remodeling complexes and histone-modifying enzymes are two predominant factors employed to accomplish this remodeling process. Chromatin relaxation occurs rapidly at the site of a DNA damage.
What is the difference between NHEJ and HR?
NHEJ modifies the broken DNA ends, and ligates them together with no regard for homology, generating deletions or insertions [2]. In contrast, HR uses an undamaged DNA template to repair the break, leading to the reconstitution of the original sequence [3].
How do Holliday junctions work?
Holliday junction, cross-shaped structure that forms during the process of genetic recombination, when two double-stranded DNA molecules become separated into four strands in order to exchange segments of genetic information.
What is MMEJ and how does it work?
As reviewed by McVey and Lee, the foremost distinguishing property of MMEJ is the use of microhomologous sequences during the alignment of broken ends before joining, thereby resulting in deletions flanking the original break.
What is the MMEJ pathway for DNA replication?
CURRENT UNDERSTANDING OF DSB REPAIR BY MMEJ The MMEJ pathway is a stepwise pathway (Figure 1C). It is initiated by end-resection near the DSB exposing short regions of complementary sequences ranging from 2 to 20 nucleotides (microhomologies).
What is MMEJ (microhomology-mediated end-joining)?
But have you heard of another double-stranded break repair mechanism: MMEJ (microhomology-mediated end-joining)? MMEJ, a form of alternative end-joining, requires only very small homology regions (5-25 bp) for repair, making it easier to construct targeting vectors.
Is MMEJ a mutagenic pathway?
MMEJ always involves insertions or deletions, so that it is a mutagenic pathway. Cells with increased MMEJ may have higher genomic instability and a predisposition towards cancer development, although this has not been demonstrated directly. Penaeus monodon is a marine crustacean widely consumed for its nutritional value.