DNA ligase

DNA ligase
DNA Repair.jpg
DNA ligase repairing chromosomal damage
Identifiers
EC number6.5.1.1
CAS number9015-85-4
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
ligase I, DNA, ATP-dependent
DNA Ligase.jpg
Identifiers
SymbolLIG1
Entrez3978
HUGO6598
OMIM126391
RefSeqNM_000234
UniProtP18858
Other data
Locus[1]
ligase III, DNA, ATP-dependent
Identifiers
SymbolLIG3
Entrez3980
HUGO6600
OMIM600940
RefSeqNM_002311
UniProtP49916
Other data
Locusq11.2-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.

Enzymatic 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
Ελληνικά: DNA λιγάση
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: ADN 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