A transposable element (TE, transposon, or jumping gene) is a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Although most of the transposable elements (TEs) that played essential roles in shaping modern eukaryotes are no longer active there is still much to discover about their legacy in shaping the function of the human genome. Almost half of the human genome is derived from TEs, primarily retrotransposons, whereas DNA transposons have contributed to about 3% of our genome. One DNA transposon, Hsmar1, was active in primates from about 50 to 37 million years ago and gave rise to SETMAR (or Metnase), a fusion protein found only in simian (anthropoid) primates with an N-terminal SET domain and C-terminal Hsmar1-derived (MAR) transposase. SETMAR encodes the only intact copy of the Hsmar1 transposase in primates, although thousands of copies of its terminal inverted repeat (TIR) sequences, which flank the transposase gene in the ancestral transposon, remain. The search for a function for SETMAR in normal cells has proven challenging; this protein is only present in simian primates and cannot easily be studied in the context of an animal model lacking the TIR elements in its genome. SETMAR is expressed in most tissues with no distinguishing specificity within the brain or other tissues. SETMAR reatins sequence-specific TIR-DNA-binding activity, mediated by the DNA-binding domain (DBD) of the transposase. Here you can see a recent crystal structure of DNA-binding domain of human SETMAR in complex with Hsmar1 terminal inverted repeat (TIR) DNA (PDB code: 7S03).
#molecularart ... #immolecular ... #transposon ... #transposase ... #DNA ... #binding ... #SETMAR ... #xray
Structure of the protein-DNA complex rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #transposon ... #transposase ... #DNA ... #binding ... #SETMAR ... #xray
Structure of the protein-DNA complex rendered with @proteinimaging and depicted with @corelphotopaint
