371
Pathway
DNA Replication Fork
DNA is composed of two long and complementary strands, with a backbone on the outside and nucleotides in the middle. During replication the two strands of DNA separate; the resulting structure is called the replication fork. The replication fork forms because enzymes called helicases surround the DNA strands and break the hydrogen bonds which hold them together. The result is that two long branches, almost like fork prongs, each of which is a DNA strand.
Replication of DNA has two main different processes. Because DNA is replicated in the 5' to 3' direction, and because both DNA strands in the replication fork are negative mirror images of each other, and because the replication fork is created on only one direction down the length of the DNA, two types of replication strands are formed: the leading and the lagging strand.
These strands are so named by the way in which DNA polymerase reads the original DNA strand and attaches the complementary nucleotides as it makes its way along the chain. Because the direction of the movement of the replication fork, and the direction of the addition of nucleotides in the leading strand is the same, the process is continuous.That is, a polymerase is able to read the DNA and add the matching nucleotide bases to it continuously. In prokaryotes DNA polymerase III is responsible for creating the leading strand.
The lagging strand is oriented in the opposite direction to the leading strand. Thus, replication of the lagging strand occurs in the opposing direction to that of the leading strand and the replication fork. As a result, replication of the lagging strand is a slower and more complicated process than that of the leading strand. Thus it is seen to lag behind the leading strand (hence the name).
Metabolic
PW000456
Center
PathwayVisualizationContext492
1100
2000
#000099
PathwayVisualization141
371
DNA Replication Fork
DNA is composed of two long and complementary strands, with a backbone on the outside and nucleotides in the middle. During replication the two strands of DNA separate; the resulting structure is called the replication fork. The replication fork forms because enzymes called helicases surround the DNA strands and break the hydrogen bonds which hold them together. The result is that two long branches, almost like fork prongs, each of which is a DNA strand.
Replication of DNA has two main different processes. Because DNA is replicated in the 5' to 3' direction, and because both DNA strands in the replication fork are negative mirror images of each other, and because the replication fork is created on only one direction down the length of the DNA, two types of replication strands are formed: the leading and the lagging strand.
These strands are so named by the way in which DNA polymerase reads the original DNA strand and attaches the complementary nucleotides as it makes its way along the chain. Because the direction of the movement of the replication fork, and the direction of the addition of nucleotides in the leading strand is the same, the process is continuous.That is, a polymerase is able to read the DNA and add the matching nucleotide bases to it continuously. In prokaryotes DNA polymerase III is responsible for creating the leading strand.
The lagging strand is oriented in the opposite direction to the leading strand. Thus, replication of the lagging strand occurs in the opposing direction to that of the leading strand and the replication fork. As a result, replication of the lagging strand is a slower and more complicated process than that of the leading strand. Thus it is seen to lag behind the leading strand (hence the name).
Metabolic
1
1536
18166979
McCulloch SD, Kunkel TA: The fidelity of DNA synthesis by eukaryotic replicative and translesion synthesis polymerases. Cell Res. 2008 Jan;18(1):148-61. doi: 10.1038/cr.2008.4.
371
Pathway
1538
Rossi, M. (2011). Distinguishing the pathways of primer removal during Eukaryotic Okazaki fragment maturation (Ph.D). University of Rochester. http://hdl.handle.net/1802/6537
371
Pathway
5355
DNA replication ATP-dependent helicase/nuclease DNA2
P51530
Key enzyme involved in DNA replication and DNA repair in nucleus and mitochondrion. Involved in Okazaki fragments processing by cleaving long flaps that escape FEN1: flaps that are longer than 27 nucleotides are coated by replication protein A complex (RPA), leading to recruit DNA2 which cleaves the flap until it is too short to bind RPA and becomes a substrate for FEN1. Also involved in 5'-end resection of DNA during double-strand break (DSB) repair: recruited by BLM and mediates the cleavage of 5'-ssDNA, while the 3'-ssDNA cleavage is prevented by the presence of RPA. Also involved in DNA replication checkpoint independently of Okazaki fragments processing. Possesses different enzymatic activities, such as single-stranded DNA (ssDNA)-dependent ATPase, 5'-3' helicase and endonuclease activities. While the ATPase and endonuclease activities are well-defined and play a key role in Okazaki fragments processing and DSB repair, the 5'-3' DNA helicase activity is subject to debate. According to various reports, the helicase activity is weak and its function remains largely unclear. Helicase activity may promote the motion of DNA2 on the flap, helping the nuclease function.
HMDBP11710
DNA2
10q21.3-q22.1
BC063664
1
3.1.-.-; 3.6.4.12
6326
5355
186
false
145
505
8
subunit
regular
150
70
99
6326
1020
189
0
0
1.0
1.0
0
2
39
2000
1055