A hairpin is a DNA structure with a narrow strand and a high frequency of mismatches. It plays a key role in the initiation of DNA replication. The molecule’s origin and function are also outlined. In addition, it is also recognized by host proteins. Merriam-Webster has no opinion on this definition. If you are wondering what a hairpin is, keep reading to learn more about it.
Mismatches in single-stranded DNA
DNA repair has been implicated in cancer and many other diseases, including genetic susceptibility and cancer. It is not fully understood, however, how mismatches are repaired, and whether they can increase cancer susceptibility. The role of replication protein A (RPA) is crucial, as it is the master regulator of mismatch repair and plays a pivotal role in cancer biology. Nonhistone proteins also play a role in the process.
The unwinding of the intermediate can be either biased toward the short path linking the strand break to the mispair, or may be a result of extensive excision of the mismatched base pairs. Interestingly, two excisions on different strands may destroy the SSA intermediate. Nevertheless, there are two models of mismatch repair: one proposes the excision of nonhomologous sequences from single-stranded DNA, and the other proposes the unwinding of strands by looking for better matches.
Function of hairpins in replication initiation
DNA hairpins are used for several important biological processes, including phage presentation, DNA replication, integration, and packaging. In addition, hairpins play important roles in several elements of DNA replication, including origin of replication of E. coli. The purpose of these determinants is still unclear, but they appear to be necessary for DNA synthesis and recombination. To better understand their role in DNA replication, we need to understand how hairpins evolved and what functions they have in the process of initiation and completion.
The main role of hairpins in DNA replication is to facilitate RNA transcription. RNA polymerase initiates transcription at the hairpin in the OriL by directing transcription and synthesis of the replication primer. To facilitate efficient RNA primer handoff, mitochondrial RNA polymerase (mtRNA) initiates transcription at the hairpin. The primosome complex ensures efficient primer handoff and protects the nascent transcript from nucleases and DNA polymerases.
Origin of hairpins
The use of hairpins dates back thousands of years. In ancient societies, hairpins were very basic and often made of bone, wood, or gemstones. In the Renaissance, hairpins became increasingly ornate and were often embellished with gems, including diamonds, rubies, and agate. Aigrette, or beaded hairpins, were popular during this period. These types of hairpins were also used to mark important occasions such as marriage or courtship.
Throughout history, hairpins have served as decorative and functional accessories. In central Africa, women wore elongated pins for decorative purposes. In 17th century Japan, kanzashi pins were fashionable. For centuries, hairpins have served as a means to hold tresses and as social status symbols. In the 1940s, bobby pins were used to achieve finger waves. But, in ancient Rome, hairpins were used for more than just ornamentation.
Recognition of hairpins by host proteins
The RNA carries multiple hairpins with GGA sequences, and the distribution of CsrA’s reads was not uniform, separating regions of high and low coverage. This suggests that CsrA binds hairpins preferentially, and may reflect a hierarchy in the capture process. In Psudomonas, RsmZ RNA sequesters the RsmE protein, which appears to be a target of CsrA.
The DNA-binding domains are similar to a variety of other molecules, with sequences arising from divergence from a common ancestor or local convergence of sequence due to adaptive replacements. Evidence from similarity searches suggests that the helix-hairpin-helix motif is conserved across 14 protein families, and is likely to mediate non-sequence-dependent interactions with DNA.