Mu-type HTH domain (IPR003314)

Short name: Mu-type_HTH

Domain relationships



Transposons are mobile genetic elements that move from one DNA site to another within their host's genome, often with profound biological consequences. The Mu genome is the largest and most efficient transposon known. The Mu transposase (MuA) is a multidomain protein, which is responsible for translocation of the Mu genome. Mu transposase can be divided into three structurally distinct domains, each with specific functions. The amino- terminal domain (30 kDa) is responsible for sequence-specific DNA binding and can further be subdivided into two separate subdomains, which bind an internal activation sequence (IAS) and the ends of the phage genome, respectively. A highly homologous IAS binding domain is also present in the Mu repressor protein (MuR), but its binding promotes lysogeny of the phage by repressing the expression of genes required for lytic growth and by directly blocking MuA access to the IAS. The IAS binding domains of the MuR and MuA proteins are DNA-binding, winged helix-turn-helix (wHTH) domains of about 75 residues (Mu- type HTH) [PMID: 7881904, PMID: 11135677].

The Mu-type HTH domain consists of a three-membered alpha-helical bundle buttressed by a three-stranded antiparallel beta-sheet with an overall B1-H1- T-H2-B2-W-B3-H3 topology (where B,H,T and W stand for beta-strand, alpha- helix, turn and wing, repectively. Helices H1 and H2 and the seven-residue turn connecting them comprise a helix-turn-helix (HTH) motif. While the general appearance of the Mu-type DNA-binding domain is similar to that of other winged HTH proteins, the connectivity of the secondary structure elements is permuted. Hence this fold represents a novel class of winged HTH DNA-binding domain [PMID: 7881904, PMID: 11135677].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0003677 DNA binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles