What is a Heteroduplex in homologous recombination?

What is a Heteroduplex in homologous recombination?

A heteroduplex is a double-stranded (duplex) molecule of nucleic acid originated through the genetic recombination of single complementary strands derived from different sources, such as from different homologous chromosomes or even from different organisms.

How is heteroduplex DNA formed?

Heteroduplexes are formed during late stages of PCR reactions when high levels of products, such as in nested PCR (N-PCR) are generated, and other reactants such as primers and functional polymerase, are depleted. They are also formed by the deliberate mixing of separately amplified reactions.

Which repair pathway functions at heteroduplex DNA?

DNA mismatch repair pathway
The DNA mismatch repair pathway MutL, another MMR-associated heteroduplex, is always composed of MLH1 with another protein: either PMS2 (MutLα), PMS1 (MutLβ), or MLH3 (MutLγ). MutLα is the most prominent MutL complex and plays the most significant role in MMR.

What is branch migration in homologous recombination?

Branch migration is the second step of genetic recombination, following the exchange of two single strands of DNA between two homologous chromosomes. The process is random, and the branch point can be displaced in either direction on the strand, influencing the degree of which the genetic material is exchanged.

What is meant by the term heteroduplex DNA?

: a nucleic-acid molecule (such as DNA) composed of two chains with each derived from a different parent molecule.

How does Heteroduplex analysis work?

Hetero-duplex analysis is a low-medium high-throughput SNP detection technique. During heteroduplex analysis, the target gene is PCR amplified and the amplified products are then denatured, re-annealed slowly to form four different double-stranded DNA molecules from the two alleles of the gene (Paniego et al., 2015).

Which protein is responsible for heteroduplex formation?

Enzymatic studies indicate that formation of the heteroduplex joint in Escherichia coli involves polymerization of RecA protein on single-stranded DNA (ssDNA) and pairing of the RecA–ssDNA nucleoprotein complex with a double-stranded DNA homologue (reviewed in refs. 1 and 2).

How mismatches within heteroduplex DNA are repaired?

Correction of a mismatch in heteroduplex DNA can result in a gene conversion event, and such correction is effected by the same mismatch repair (MMR) machinery that corrects errors made during DNA replication.

Why is branch migration important?

Branch migration of Holliday junctions may serve several important functions such as affecting the length of genetic information transferred between homologous chromosomes during meiosis, restarting stalled replication forks, and ensuring the faithful repair of double strand DNA breaks by homologous recombination.

Which type of DNA is connected by a Holliday junction?

duplex DNA species
Holliday junctions must be processed into duplex DNA species, and this can occur in two main ways. One is by the action of nucleases that are selective for branched DNA—the junction-resolving enzymes.

What is the function of RecBCD?

Summary: The RecBCD enzyme of Escherichia coli is a helicase-nuclease that initiates the repair of double-stranded DNA breaks by homologous recombination. It also degrades linear double-stranded DNA, protecting the bacteria from phages and extraneous chromosomal DNA.

What is heteroduplex mobility assay?

Heteroduplex mobility assay (HMA) has been used for the study of the variability of human immunodeficiency virus type 1 (HIV1) surface envelope (env) glycoprotein coding sequences (Delwart et al., 1993, Delwart et al., 1994) and genetic relationships between multiple viral DNA template molecules can be rapidly …

What is Heteroduplex rejection?

Mismatches also appear in heteroduplex DNA intermediates formed during recombination between nearly identical sequences, and can be corrected by MMR or removed through an unwinding mechanism, known as anti-recombination or heteroduplex rejection.

Does branch migration require ATP?

We show that RuvAB-mediated branch migration requires ATP and can bypass UV-induced DNA lesions. At high RuvB concentrations, the requirement for RuvA is overcome, indicating that the RuvB ATPase provides the motor force for branch migration.

Why is Holliday junction important?

The Holliday junction is a key intermediate in homologous recombination, a biological process that increases genetic diversity by shifting genes between two chromosomes, as well as site-specific recombination events involving integrases. They are additionally involved in repair of double-strand breaks.

Which component cleaves the DNA strands at Holliday junction?

Hallmark Characteristics. Holliday junction cleavage, which generates two unconnected DNA duplexes, is catalyzed by a group of structure-selective endonucleases called HJ resolvases.

What role does the RecBCD protein play in recombination?

What is the role of RecA in recombination?

In addition to its role in homologous recombination, RecA functions as a coprotease for the LexA protein. In a healthy cell, LexA represses the expression of genes encoding DNA repair proteins (SOS genes). Upon injury of DNA, LexA catalyzes its own digestion, thereby allowing synthesis of necessary SOS proteins.

What are mismatch repair proteins?

MMR proteins are nuclear enzymes, which participate in repair of base-base mismatch that occur during DNA replication in proliferating cells. The proteins form complexes (heterodimers) that bind to areas of abnormal DNA and initiates its removal.