leading strand elongation
Definition
Target type: biologicalprocess
The process in which an existing DNA strand is extended continuously in a 5' to 3' direction by activities including the addition of nucleotides to the 3' end of the strand, complementary to an existing template, as part of DNA replication. Leading strand elongation proceeds in the same direction as the replication fork. [GOC:mah, ISBN:071673706X, ISBN:0815316194]
Leading strand elongation is a fundamental process in DNA replication, where a new DNA strand is synthesized continuously in the 5' to 3' direction. It occurs on the leading template strand, which runs in the 3' to 5' direction, allowing for continuous synthesis. This process involves the following steps:
1. **Initiation:** The process begins with the binding of DNA helicase to the origin of replication, unwinding the double-stranded DNA helix to expose the template strands.
2. **Primer binding:** An RNA primer, synthesized by primase, binds to the 3' end of the leading template strand. This primer provides a free 3' hydroxyl group for DNA polymerase to initiate synthesis.
3. **Elongation:** DNA polymerase III, the primary enzyme responsible for DNA synthesis, binds to the primer and begins adding nucleotides complementary to the template strand in the 5' to 3' direction. This process is highly accurate, with proofreading mechanisms to ensure fidelity.
4. **Continuous synthesis:** As the DNA polymerase moves along the template strand, it continuously adds nucleotides to the growing leading strand, creating a new DNA strand complementary to the template.
5. **Termination:** When DNA polymerase reaches the end of the template strand, the process is terminated. This may involve a specific termination sequence or a physical barrier.
The leading strand elongation process is facilitated by several essential factors, including:
- **DNA helicase:** Unwinds the DNA helix, separating the two strands.
- **Primase:** Synthesizes RNA primers to initiate DNA synthesis.
- **DNA polymerase III:** Adds nucleotides to the growing DNA strand.
- **Single-stranded binding proteins (SSBs):** Stabilize the single-stranded DNA template.
- **Topoisomerases:** Relieve torsional stress ahead of the replication fork.
Leading strand elongation is a critical step in DNA replication, ensuring accurate and efficient duplication of the genetic material. This process is essential for cell division, growth, and development.'
"
Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Proliferating cell nuclear antigen | A proliferating cell nuclear antigen that is encoded in the genome of human. [PRO:DNx] | Homo sapiens (human) |
| DNA polymerase alpha catalytic subunit | A DNA polymerase alpha catalytic subunit that is encoded in the genome of human. [PRO:DNx] | Homo sapiens (human) |
Compounds (16)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| digallic acid | digallic acid: structure given in first source | benzoate ester; gallate ester | |
| foscarnet | Foscarnet: An antiviral agent used in the treatment of cytomegalovirus retinitis. Foscarnet also shows activity against human herpesviruses and HIV. phosphonoformic acid : Phosphoric acid in which one of the hydroxy groups is replaced by a carboxylic acid group. It is used as the trisodium salt as an antiviral agent in the treatment of cytomegalovirus retinitis (CMV retinitis, an inflamation of the retina that can lead to blindness) and as an alternative to ganciclovir for AIDS patients who require concurrent antiretroviral therapy but are unable to tolerate ganciclovir due to haematological toxicity. | carboxylic acid; one-carbon compound; phosphonic acids | antiviral drug; geroprotector; HIV-1 reverse transcriptase inhibitor; sodium-dependent Pi-transporter inhibitor |
| 3,3',5-triiodothyroacetic acid | tiratricol : A monocarboxylic acid that is (4-hydroxy-3,5-diiodophenyl)acetic acid in which the phenolic hydroxy group has been replaced by a 4-hydroxy-3-iodophenoxy group. It is a thyroid hormone analogue that has been used in the treatment of thyroid hormone resistance syndrome. | ||
| 3,3',5-triiodothyropropionic acid | aromatic ether | ||
| thyroxine | thyroxine : An iodothyronine compound having iodo substituents at the 3-, 3'-, 5- and 5'-positions. Thyroxine: The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (MONOIODOTYROSINE) and the coupling of iodotyrosines (DIIODOTYROSINE) in the THYROGLOBULIN. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form TRIIODOTHYRONINE which exerts a broad spectrum of stimulatory effects on cell metabolism. | 2-halophenol; iodophenol; L-phenylalanine derivative; non-proteinogenic L-alpha-amino acid; thyroxine; thyroxine zwitterion | antithyroid drug; human metabolite; mouse metabolite; thyroid hormone |
| triiodothyronine | 3,3',5-triiodo-L-thyronine : An iodothyronine compound having iodo substituents at the 3-, 3'- and 5-positions. Although some is produced in the thyroid, most of the 3,3',5-triiodo-L-thyronine in the body is generated by mono-deiodination of L-thyroxine in the peripheral tissues. Its metabolic activity is about 3 to 5 times that of L-thyroxine. The sodium salt is used in the treatment of hypothyroidism. Triiodothyronine: A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5' position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly T3. | 2-halophenol; amino acid zwitterion; iodophenol; iodothyronine | human metabolite; mouse metabolite; thyroid hormone |
| zidovudine triphosphate | |||
| 3,5-diiodothyronine, (l)-isomer | phenylalanine derivative | ||
| 3,3'-diiodothyronine | 3,3'-diiodothyronine: RN given refers to unlabeled cpd without isomeric designation | 3,3'-diiodothyronine; amino acid zwitterion | human metabolite |
| 3,5-diiodothyropropionic acid | 3,5-diiodothyropropionic acid : A monocarboxylic acid that is (4-hydroxy-3,5-diiodophenyl)propanoic acid in which the phenolic hydroxy group has been replaced by a 4-hydroxyphenyl group. An ionotropic analogue of L-thyroxine. 3,5-diiodothyropropionic acid: a cardiotonic thyroid hormone analog | aromatic ether; monocarboxylic acid; organoiodine compound; phenols | |
| resveratrol | trans-resveratrol : A resveratrol in which the double bond has E configuration. | resveratrol | antioxidant; phytoalexin; plant metabolite; quorum sensing inhibitor; radical scavenger |
| TTP | pyrimidine ribonucleoside 5'-triphosphate | ||
| aphidicolin | aphidicolin : A tetracyclic diterpenoid that has an tetradecahydro-8,11a-methanocyclohepta[a]naphthalene skeleton with two hydroxymethyl substituents at positions 4 and 9, two methyl substituents at positions 4 and 11b and two hydroxy substituents at positions 3 and 9. An antibiotic with antiviral and antimitotical properties. Aphidicolin is a reversible inhibitor of eukaryotic nuclear DNA replication. Aphidicolin: An antiviral antibiotic produced by Cephalosporium aphidicola and other fungi. It inhibits the growth of eukaryotic cells and certain animal viruses by selectively inhibiting the cellular replication of DNA polymerase II or the viral-induced DNA polymerases. The drug may be useful for controlling excessive cell proliferation in patients with cancer, psoriasis or other dermatitis with little or no adverse effect upon non-multiplying cells. | tetracyclic diterpenoid | antimicrobial agent; antimitotic; antineoplastic agent; antiviral drug; apoptosis inducer; Aspergillus metabolite; DNA synthesis inhibitor; EC 2.7.7.7 (DNA-directed DNA polymerase) inhibitor; fungal metabolite |
| pnu183792 | PNU183792: structure in first source | ||
| GS-443902 | GS-441524 triphosphate: intracellular active metabolite of remdesivir GS-443902 : An organic triphosphate that is GS-441524 in which the 5'-hydroxy group has been replaced by a triphosphate group. It is the active metabolite of remdesivir. | aromatic amine; C-nucleoside; nitrile; organic triphosphate; pyrrolotriazine | anticoronaviral agent; antiviral drug; drug metabolite |
| n(2)-(4-n-butylphenyl) 2'-deoxyguanosine | N(2)-(4-n-butylphenyl) 2'-deoxyguanosine: RN & structure given in first source |