4. WHAT IS DNA LIGASE?
DNA ligase is a type of
enzyme that facilitates the
joining of DNA strands
together by catalyzing the
formation of a
phosphodiester bond.
DNA ligase is also called
“molecular glue”. During
DNA replication, It attaches
the Okazaki fragments
formed from the lagging
strand during the
replication of DNA.
5. DNA ligase works by catalyzing the
formation of a phosphodiester bond
between nucleotides on one strand
of a double stranded DNA molecule.
HOW DOES DNA LIGASE
WORK?
6. DNA ligases play an essential role
in maintaining genomic integrity by
joining breaks in the phosphodiester
backbone of DNA that occur during
replication and recombination, and as a
consequence of DNA damage and its repair.
IMPORTANCE
7. STEPS OF DNA LIGASE
• In the first step, the DNA fragments or DNA segments or Okazaki
fragments are reorganized with their active sites.
• The lysine residue of the active site of the Ligase gets adenylated
with the addition of AMP. The release of pyrophosphate
accompanies adenylation of Ligase.
• Ligase transfer the AMP to the 5′ phosphate end of the donor
with the formation of the pyrophosphate bond.
• The 5′ phosphate end of the donor is linked to the 3′ hydroxyl
end of the receptor with phosphodiester bond formation.
8. APPLICATION
• DNA ligases play a key role in DNA cloning and in NGS library
preparation.
• In cloning applications, DNA ligases are largely used to bond the ends of a
DNA fragment to the ends of a plasmid or vector. This vector will
ultimately be transformed into cells of interest where it will recombine
with the cell’s wild-type DNA, generating a mutant.
9. APPLICATION
• DNA ligases play a key role in DNA cloning and in NGS library
preparation.
• In cloning applications, DNA ligases are largely used to bond the ends of a
DNA fragment to the ends of a plasmid or vector. This vector will
ultimately be transformed into cells of interest where it will recombine
with the cell’s wild-type DNA, generating a mutant.
10. ADVANTAGES
• DNA REPAIR: DNA Ligase plays a crucial role in
repairing DNA damage; such as nicks and gaps in the
DNA molecule.
• Recombinant DNA Technology: DNA Ligase is widely
used in molecular biology techniques, such as cloning and
recombinant DNA technology.
• Without DNA Ligase, the process of mutation will not
complete
11. ADVANTAGES
• DNA REPAIR: DNA Ligase plays a
crucial role in repairing DNA
damage; such as nicks and gaps in
the DNA molecule.
• Recombinant DNA Technology: DNA
Ligase is widely used in molecular
biology techniques, such as cloning
and recombinant DNA technology.
• Without DNA Ligase, the process of
mutation will not be complete.
DISADVANTAGES
• Although DNA Ligase is highly accurate in
sealing DNA strands, there is still a
possibility of errors such as misligation,
resulting in mutations or rearrangements in
the DNA sequence.
• Size Limitations: DNA Ligases may have
limitations on the size of DNA fragments
they can effectively ligate.
• Specificity Issues: While DNA Ligases
generally have high specificity for joining
DNA strands, they may sometimes ligate
DNA fragments with incompatible ends or
ligate non-specific DNA molecules, leading to
undesirable outcomes in molecular biology
experiments.
