PROSITE documentation PDOC51784
Exonuclease I (ExoI) SH3-like and C-terminal domains profiles


In bacteria, exonuclease I (ExoI) is a monomeric processive 3'-5' exonuclease that degrades single-stranded DNA. The enzyme has been implicated as primarily being involved in repairing frameshift mutations. ExoI consists of three domains: an N-terminal nuclease domain with homology to the proofreading domain of E. coli DNA polymereae I and other DnaQ superfamily enzymes, a central domain with a portion that resembles an SH3 domain fold and a C-terminal α-helical domain. While a typical SH3-like domain consists of five or six antiparallel β-strands that form a compact β-sandwich, the β-sandwich of the SH3-like domain in ExoI is surrounded by α-helices, resulting in a substantially elaborated fold (see <PDB:1FXX>) [1,2,3].

The profile we developed covers the entire ExoI SH3-like and C-terminal domains.

Last update:

December 2015 / First entry.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

EXOI_C, PS51785; Exonuclease I (ExoI) C-terminal domain profile  (MATRIX)

EXOI_SH3, PS51784; Exonuclease I (ExoI) SH3-like domain profile  (MATRIX)


1AuthorsBreyer W.A. Matthews B.W.
TitleStructure of Escherichia coli exonuclease I suggests how processivity is achieved.
SourceNat. Struct. Biol. 7:1125-1128(2000).
PubMed ID11101894

2AuthorsBusam R.D.
TitleStructure of Escherichia coli exonuclease I in complex with thymidine 5'-monophosphate.
SourceActa Crystallogr. D 64:206-210(2008).
PubMed ID18219121

3AuthorsKorada S.K.C. Johns T.D. Smith C.E. Jones N.D. McCabe K.A. Bell C.E.
TitleCrystal structures of Escherichia coli exonuclease I in complex with single-stranded DNA provide insights into the mechanism of processive digestion.
SourceNucleic Acids Res. 41:5887-5897(2013).
PubMed ID23609540

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