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Enterobacteria phage λ is a bacterial virus, or bacteriophage, that infects the bacterial species Escherichia coli. It was discovered by Esther Lederberg in 1950. The wild type of this virus has a temperate life cycle that allows it to either reside within the genome of its host through lysogeny or enter into a lytic phase, during which it kills and lyses the cell to produce offspring. Lambda strains, mutated at specific sites, are unable to lysogenize cells; instead, they grow and enter the lytic cycle after superinfecting an already lysogenized cell.
Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two hybridized nucleic acid strands, using energy from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases.
A ρ factor is a bacterial protein involved in the termination of transcription. Rho factor binds to the transcription terminator pause site, an exposed region of single stranded RNA after the open reading frame at C-rich/G-poor sequences that lack obvious secondary structure.
The SOS response is a global response to DNA damage in which the cell cycle is arrested and DNA repair and mutagenesis is induced. The system involves the RecA protein. The RecA protein, stimulated by single-stranded DNA, is involved in the inactivation of the repressor (LexA) of SOS response genes thereby inducing the response. It is an error-prone repair system that contributes significantly to DNA changes observed in a wide range of species.
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encodes its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA damage, resulting in tens of thousands of individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. When normal repair processes fail, and when cellular apoptosis does not occur, irreparable DNA damage may occur, including double-strand breaks and DNA crosslinkages. This can eventually lead to malignant tumors, or cancer as per the two-hit hypothesis.
RNA polymerase II is a multiprotein complex that transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. It is one of the three RNAP enzymes found in the nucleus of eukaryotic cells. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase. A wide range of transcription factors are required for it to bind to upstream gene promoters and begin transcription.
Nucleotide excision repair is a DNA repair mechanism. DNA damage occurs constantly because of chemicals, radiation and other mutagens. Three excision repair pathways exist to repair single stranded DNA damage: Nucleotide excision repair (NER), base excision repair (BER), and DNA mismatch repair (MMR). While the BER pathway can recognize specific non-bulky lesions in DNA, it can correct only damaged bases that are removed by specific glycosylases. Similarly, the MMR pathway only targets mismatched Watson-Crick base pairs.
DNA polymerase II is a prokaryotic DNA-dependent DNA polymerase encoded by the PolB gene.
In molecular biology, a termination factor is a protein that mediates the termination of RNA transcription by recognizing a transcription terminator and causing the release of the newly made mRNA. This is part of the process that regulates the transcription of RNA to preserve gene expression integrity and are present in both eukaryotes and prokaryotes, although the process in bacteria is more widely understood. The most extensively studied and detailed transcriptional termination factor is the Rho (ρ) protein of E. coli.
The rpoB gene encodes the β subunit of bacterial RNA polymerase and the homologous plastid-encoded RNA polymerase (PEP). It codes for 1342 amino acids in E. coli, making it the second-largest polypeptide in the bacterial cell. It is targeted by the rifamycin family of antibacterials, such as rifampin. Mutations in rpoB that confer resistance to rifamycins do so by altering the protein's drug-binding residues, thereby reducing affinity for these antibiotics.
UvrABC endonuclease is a multienzyme complex in bacteria involved in DNA repair by nucleotide excision repair, and it is, therefore, sometimes called an excinuclease. This UvrABC repair process, sometimes called the short-patch process, involves the removal of twelve nucleotides where a genetic mutation has occurred followed by a DNA polymerase, replacing these aberrant nucleotides with the correct nucleotides and completing the DNA repair. The subunits for this enzyme are encoded in the uvrA, uvrB, and uvrC genes. This enzyme complex is able to repair many different types of damage, including cyclobutyl dimer formation.
Richard D. Wood is an American molecular biologist specializing in research on DNA repair and mutation. He is known for pioneering studies on nucleotide excision repair (NER), particularly for reconstituting the minimum set of proteins involved in this process, identifying proliferating cell nuclear antigen (PCNA) as part of the NER complex and identifying mammalian repair polymerases.
Evelyn M. Witkin was an American bacterial geneticist at Cold Spring Harbor Laboratory (1944–1955), SUNY Downstate Medical Center (1955–1971), and Rutgers University (1971–1991). Witkin was considered innovative and inspirational as a scientist, teacher and mentor.
DNA excision repair protein ERCC-6 is a protein that in humans is encoded by the ERCC6 gene. The ERCC6 gene is located on the long arm of chromosome 10 at position 11.23.
DNA excision repair protein ERCC-8 is a protein that in humans is encoded by the ERCC8 gene.
PcrA, standing for plasmid copy reduced is a helicase that was originally discovered in a screen for chromosomally encoded genes that are affected in plasmid rolling circle replication in the Gram-positive pathogen Staphylococcus aureus.
Very short patch (VSP) repair is a DNA repair system that removes GT mismatches created by the deamination of 5-methylcytosine to thymine. This system exists because the glycosylases which normally target deaminated bases cannot target thymine.
Genome instability refers to a high frequency of mutations within the genome of a cellular lineage. These mutations can include changes in nucleic acid sequences, chromosomal rearrangements or aneuploidy. Genome instability does occur in bacteria. In multicellular organisms genome instability is central to carcinogenesis, and in humans it is also a factor in some neurodegenerative diseases such as amyotrophic lateral sclerosis or the neuromuscular disease myotonic dystrophy.
Houra Merrikh is an Iranian-American microbiologist. She is a full professor at Vanderbilt University in the Department of Biochemistry. Her field of work is antibiotic resistance and bacterial evolvability.
Transcription-translation coupling is a mechanism of gene expression regulation in which synthesis of an mRNA (transcription) is affected by its concurrent decoding (translation). In prokaryotes, mRNAs are translated while they are transcribed. This allows communication between RNA polymerase, the multisubunit enzyme that catalyzes transcription, and the ribosome, which catalyzes translation. Coupling involves both direct physical interactions between RNA polymerase and the ribosome, as well as ribosome-induced changes to the structure and accessibility of the intervening mRNA that affect transcription.
References
- ↑ PMID 27864884
- 1 2 Palisoc, Mhean (2019-01-03). "Merrikh Lab Working to Defeat Drug-Resistant Superbugs". Science and Technology Research News. Retrieved 2019-10-22.
- ↑ Roberts, Jeffrey; Park, Joo-Seop (2004). "Mfd, the bacterial transcription repair coupling factor: translocation, repair and termination". Current Opinion in Microbiology. 7 (2): 120–125. doi:10.1016/j.mib.2004.02.014. PMID 15063847.
- ↑ Deaconescu, Alexandra M.; Artsimovitch, Irina; Grigorieff, Nikolaus (December 2012). "Interplay of DNA repair with transcription: from structures to mechanisms". Trends in Biochemical Sciences. 37 (12): 543–552. doi:10.1016/j.tibs.2012.09.002. ISSN 0968-0004. PMC 3588851 . PMID 23084398.
- ↑ Deaconescu, Alexandra M.; Chambers, Anna L.; Smith, Abigail J.; Nickels, Bryce E.; Hochschild, Ann; Savery, Nigel J.; Darst, Seth A. (2006). "Structural Basis for Bacterial Transcription-Coupled DNA Repair". Cell. 124 (3): 507–520. doi: 10.1016/j.cell.2005.11.045 . PMID 16469698.
- ↑ Park, Joo-Seop; Marr, Michael T.; Roberts, Jeffrey W. (2002-06-14). "E. coli Transcription repair coupling factor (Mfd protein) rescues arrested complexes by promoting forward translocation". Cell. 109 (6): 757–767. doi: 10.1016/s0092-8674(02)00769-9 . ISSN 0092-8674. PMID 12086674.
- ↑ "Il y a peut-être une solution pour stopper la résistance aux antibiotiques". Slate.fr (in French). 2018-12-31. Retrieved 2019-10-22.
- ↑ 10.1101/2022.09.26.509600
- ↑ 10.1038/srep29349
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