Mechanism of specific LexA cleavage: autodigestion and the role of RecA coprotease

Biochimie. 1991 Apr;73(4):411-21. doi: 10.1016/0300-9084(91)90108-d.


Specific LexA cleavage can occur under two different conditions: RecA-mediated cleavage requires an activated form of RecA, while an intramolecular self-cleavage termed autodigestion proceeds spontaneously at high pH and does not involve RecA. The two cleavage reactions are closely related. We postulate that RecA stimulates autodigestion rather than acting as a typical protease, and it is proposed to term this activity 'RecA coprotease' to emphasize this indirect role. The mechanism of autodigestion is similar to that of a serine protease, and RecA appears to act by reducing the pKa of a critical lysine residue LexA. A new class of mutants, termed lexA (IndS), is described; these mutations increase the rate of LexA cleavage.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • DNA Damage*
  • Hydrolysis
  • Molecular Sequence Data
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • SOS Response, Genetics*
  • Serine Endopeptidases / genetics
  • Serine Endopeptidases / metabolism*


  • Bacterial Proteins
  • LexA protein, Bacteria
  • Repressor Proteins
  • Serine Endopeptidases