Mutational analysis of the RecA protein L1 region identifies this area as a probable part of the co-protease substrate binding site.

  • Nastri H
  • Guzzo A
  • Lange C
 et al. 
  • 6


    Mendeley users who have this article in their library.
  • 14


    Citations of this article.


Previous mutational analysis of the L1 region of the RecA protein suggested that Gly-157 and Glu-158 are 'hot-spots' for the occurrence of constitutive LexA co-protease mutants (coprt[c]). In the present study, we clearly establish that position 157 is a hot-spot for the occurrence of such mutants, as 12 of 14 and 10 of 14 substitutions result in this phenotype for UmuD and LexA cleavage respectively. The frequency of such mutations at position 158 is somewhat lower, 8 of 13 and 5 of 13 for UmuD and LexA respectively. Comparison of the UmuD vs. LexA co-protease activity for all single mutants with substitutions at positions 154, 155, 156, 157 and 158 (47 in total) reveals that, although there is good agreement among most mutants regarding their ability to cleave both LexA and UmuD, there are two in particular (Glu-154-->Asp and Glu-154-->Gln) that show a clear preference for cleavage of UmuD. We also show that three second-site mutations that completely suppress coprt(c) activity toward LexA have little or no effect on the coprt(c) activity of the primary mutant toward UmuD. In addition, we observe a high frequency of second-site suppressor mutations, suggesting a functional interaction among side-chains in this region. Together, these results support the idea that the L1 region of RecA makes up part of the co-protease substrate-binding site.

Author-supplied keywords

  • Binding Sites/genetics/physiology
  • DNA Mutational Analysis
  • Endopeptidases/ metabolism
  • Gene Frequency
  • Genetic/genetics
  • Glutamic Acid/genetics
  • Glycine/genetics
  • Isoleucine/genetics
  • Point Mutation/genetics/physiology
  • Rec A Recombinases/ chemistry/ genetics
  • Substrate Specificity
  • Suppression

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • H G Nastri

  • A Guzzo

  • C S Lange

  • G C Walker

  • K L Knight

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free