DNA ligase

DNA ligase
DNA Repair.jpg
DNA ligase repairing chromosomal damage
Identifiers
EC number 6.5.1.1
CAS number 9015-85-4
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / QuickGO
ligase I, DNA, ATP-dependent
DNA Ligase.jpg
Identifiers
Symbol LIG1
Entrez 3978
HUGO 6598
OMIM 126391
RefSeq NM_000234
UniProt P18858
Other data
Locus [1]
ligase III, DNA, ATP-dependent
Identifiers
Symbol LIG3
Entrez 3980
HUGO 6600
OMIM 600940
RefSeq NM_002311
UniProt P49916
Other data
Locus q11.2-q12

DNA ligase is a specific type of enzyme, a ligase, ( 6.5.1.1) that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. It plays a role in repairing single-strand breaks in duplex DNA in living organisms, but some forms (such as DNA ligase IV) may specifically repair double-strand breaks (i.e. a break in both complementary strands of DNA). Single-strand breaks are repaired by DNA ligase using the complementary strand of the double helix as a template, [1] with DNA ligase creating the final phosphodiester bond to fully repair the DNA.

DNA ligase is used in both DNA repair and DNA replication (see Mammalian ligases). In addition, DNA ligase has extensive use in molecular biology laboratories for recombinant DNA experiments (see Applications in molecular biology research). Purified DNA ligase is used in gene cloning to join DNA molecules together to form recombinant DNA.

Ligase mechanism

The mechanism of DNA ligase is to form two covalent phosphodiester bonds between 3' hydroxyl ends of one nucleotide ("acceptor"), with the 5' phosphate end of another ("donor"). Two ATP molecules are consumed for each phosphodiester bond formed. AMP is required for the ligase reaction, which proceeds in four steps:

1. Reorganization of activity site such as nicks in DNA segments or Okazaki fragments etc.

2. Adenylation (addition of AMP) of a lysine residue in the active center of the enzyme, pyrophosphate is released;

3. Transfer of the AMP to the 5' phosphate of the so-called donor, formation of a pyrophosphate bond;

4. Formation of a phosphodiester bond between the 5' phosphate of the donor and the 3' hydroxyl of the acceptor. [2]

A pictorial example of how a ligase works (with sticky ends)

Ligase will also work with blunt ends, although higher enzyme concentrations and different reaction conditions are required.

Other Languages
català: ADN ligasa
čeština: DNA ligáza
Deutsch: DNA-Ligase
español: ADN ligasa
français: ADN ligase
galego: ADN ligase
Հայերեն: ԴՆԹ լիգազ
Bahasa Indonesia: DNA ligase
italiano: DNA ligasi
македонски: ДНК лигаза
Nederlands: DNA-ligase
日本語: DNAリガーゼ
polski: Ligaza DNA
português: DNA ligase
slovenčina: DNA ligáza
српски / srpski: DNK ligaza
srpskohrvatski / српскохрватски: DNK ligaza
svenska: DNA-ligas
Türkçe: DNA ligaz
українська: ДНК-лігаза
中文: DNA連接酶