Proposed acquisition of an animal protein domain by bacteria

Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):8990-4. doi: 10.1073/pnas.89.19.8990.


A systematic screen of a protein sequence data base confirms that the fibronectin type III (Fn3) domain is widely distributed among animal proteins and occurs also in several bacterial carbohydrate-splitting enzymes. The motif has yet to be identified in proteins from plants or fungi. All indications are that the bacterial sequences are much too similar to the animal type to be the result of conventional vertical descent. Rather, it is likely that the bacterial units were initially acquired from an animal source and are being spread further by horizontal transfers between distantly related bacteria.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacteria / genetics*
  • Biological Evolution*
  • Fibronectins / genetics*
  • Humans
  • Molecular Sequence Data
  • Phylogeny
  • Proteins / genetics*
  • Sequence Homology, Amino Acid


  • Fibronectins
  • Proteins