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NlaIII
Bacteria contains restriction modification systems to prevent foreign DNA from being incorporated into the double-helix of DNA and ultimately in protein synthesis. The restriction modification systems consist of enzymes that cleave segments of palindromic DNA and methylation of its own DNA sequence. The methylation prevents bacteria’s own DNA from being modified.

NlaIII (pronounced “n-l-a three”) is a restriction endonuclease enzyme that was isolated from the bacteria Neisseria lactamica and more recently, is produced in E. coli using recombinant DNA. Restriction endonuclease enzymes are those that cut DNA at or near specific DNA sequences(restriction sites) on the DNA strand. NlaIII cleaves double-stranded DNA into fragments. NlaIII recognizes the sequence 5’-CATG-3’ and cleaves the 3’ side of a G base on the DNA strands. This then produces a 3’ four base overhang which can be ligated to other complementary bases and transformed into a cell.

Primary Structure
NlaIII contains the HNH motif in its active site which places it in the HNH family of restriction endonucleases. HNH is the abbreviation for the characteristic domain residue Histidine-Asparagine-Histidine.

Tertiary and Quarternary Structure
The solved crystal structure of NlaIII subunits reveal that it is a P subtype orthodox enzyme composed of 2 subunits that recognizes a single palindromic site.

Uses
Rosalee Rasmussen used restriction enzymes including NlaIII to determine the species of salmon through Restriction Fragment Length Polymorphism analysis(RFLP).

Used for DNA mapping, gene cloning, DNA fragmentation and analysis, building DNA catalogues and epigenetic modifications. .