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Microbiology
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Katherine Belfield, Roger Bayston
Bacteria synthesise enzymes and other proteins, including toxins.Transported out of the cell through phospholipid membrane(s).Other enzymes are also synthesised to control DNA replication.Most syntheses are carried out in ribosomes — protein synthesis organelles consisting mainly of RNA.These syntheses are major targets for common antibiotics (Figures 4.3 and 4.4).
Finding a Target
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
During cell division, identical copies of these genes must be transmitted to each daughter cell. The information contained within the genes is written as the unique linear sequence of nucleotides that make up that section of the DNA. A consequence of complementary base pairing means that each strand contains identical information and can serve as a template for the replication of that information. This is the principle that underpins DNA replication and protein synthesis. Errors may occur during DNA replication and this causes mutations.
Genetics
Published in Rachel U Sidwell, Mike A Thomson, Concise Paediatrics, 2020
Rachel U Sidwell, Mike A Thomson
This occurs in a sequence: DNA helix splits to form two single strandsNew complementary base pairs, i.e. C with G, and T with A, are added to the single strands at the 3′ end (so the new DNA replication grows from 5′ to 3’). DNA polymerase enzyme adds the new nucleotides.
Discovery of small molecule inhibitors of Plasmodium falciparum apicoplast DNA polymerase
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Supreet Kaur, Nicholas S. Nieto, Peter McDonald, Josh R. Beck, Richard B. Honzatko, Anuradha Roy, Scott W. Nelson
Nearly 600 proteins exist within the apicoplast and approximately 4% of those are involved in replication of the 35 kb apicoplast genome12. Enzymes that carry-out the fundamental process of DNA replication are promising drug targets. Indeed, ciprofloxacin, a DNA type II topoisomerase inhibitor, has anti-malarial activity; however, antiparasitic properties could be due to off-target effects instead of, or as well as, inhibition of the P. falciparum gyrase13 The apicoplast DNA polymerase (apPOL) represents an attractive target for anti-malarial drug development14. apPOL exhibits low amino-acid sequence identity to replicative polymerases from other species. Outside of Apicomplexa, the nearest homolog (35% sequence identity) is the replicative polymerase from the cyanobacteria Cyanothece sp. PCC 8802. The most similar human DNA polymerases are the lesion bypass polymerases theta and nu (23% and 22% sequence identity, respectively), with the other human DNA polymerases displaying less than 20% identity, providing a foundation for selectivity. On the other hand, apPOLs from the two primary causative agents of human Malaria (P. falciparum and P. vivax) are 84% sequence identical, suggesting that drugs targeting P. falciparum apPOL would be effective in treating Malaria caused by P. vivax.
Emergence of varicella-zoster virus resistance to acyclovir: epidemiology, prevention, and treatment
Published in Expert Review of Anti-infective Therapy, 2021
Kimiyasu Shiraki, Masaya Takemoto, Tohru Daikoku
Double-stranded DNA needs to be separated into two single strands (replication fork) before DNA synthesis, and complementary strands are synthesized from each DNA strand to produce two new double-stranded DNA molecules during DNA replication (Figure 3). The HP complex is responsible for unwinding viral DNA at the replication fork, separating double-stranded DNA into two single strands, and synthesizing RNA primers (Okazaki fragments) in the lagging strand for DNA synthesis. DNApol initiates complementary DNA synthesis in the two separated DNA strands. The HP complex consists of three proteins: VZVORF55 (helicase), VZVORF6 (primase), and VZVORF52 (cofactor). The helicase unwinds the duplex DNA ahead of the fork and separates the double strand into two single strands. The primase lays down RNA primers that extend the two-subunit DNApol. The HP complex possesses multienzymatic activities, including DNA-dependent ATPase, helicase, and primase activities, all of which are required for the HP complex to function in viral DNA replication.
Overexpression of long non-coding RNA MCM3AP-AS1 in breast cancer tissues compared to adjacent non-tumour tissues
Published in British Journal of Biomedical Science, 2021
A Riahi, M Hosseinpour-Feizi, A Rajabi, M Akbarzadeh, V Montazeri, R Safaralizadeh
One of the essential elements of pre-replication complexes is minichromosome maintenance (MCM) proteins that are composed of six-component complexes (MCM2-MCM7) by DNA helicase activities. These complexes are involved in the initiation and extension processes of DNA replication and lead to restrictions of DNA replication to once per cell cycle. Minichromosome maintenance complex component 3-associated protein (MCM3AP) is located at 21q22.3, and codes for a protein that binds to and acetylates MCM3 through acetyltransferase functions. The interaction of MCM3AP with MCM3 is crucial for not only its entry into the nucleus but also its binding to chromatin. Increased MCM3AP expression level plays a role in inhibiting the S phase of the cell cycle, and its regulatory role as a tumour suppressor gene with a low level of expression has been proved in breast cancer. MCM3AP-AS1 is a long non-coding RNA antisense1 for MCM3AP [16–19]. The roles and regulatory mechanisms of lncRNA MCM3AP-AS1 in breast cancer are unclear.