Regulation of penicillin G acylase gene expression in Escherichia coli by repressor PaaX and the cAMP-cAMP receptor protein complex

J Biol Chem. 2004 Aug 6;279(32):33253-62. doi: 10.1074/jbc.M404348200. Epub 2004 May 24.


The pga gene of Escherichia coli W ATCC11105 encodes a penicillin G acylase whose expression is regulated at both the transcriptional and post-transcriptional level. In this work we have shown that PaaX is the repressor of pga expression, and we have identified its binding consensus as TGATTC(N27)GAATCA. We conclude that the process of "PAA induction" actually involves relief of pga from repression by PaaX. Other features of the pga promoter have also been characterized. (i) It has a native class III cAMP-receptor protein (CRP)-dependent promoter with two CRP-binding sites. (ii) The downstream CRP-binding site II has higher affinity. (iii) Binding of cAMP-CRP to both sites (I + II) is required for maximal expression. We have also shown that the PaaX-binding site overlaps with the CRP-binding site I. This implies that PaaX and the cAMP-CRP compete for binding to the region around the CRP-binding site I and therefore have antagonistic effects on pga expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Binding Sites
  • Binding, Competitive
  • Consensus Sequence
  • Cyclic AMP / metabolism*
  • Cyclic AMP Receptor Protein
  • DNA / chemistry
  • DNA / metabolism
  • Electrophoretic Mobility Shift Assay
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Expression Regulation, Enzymologic*
  • Mutagenesis, Site-Directed
  • Penicillin Amidase / genetics*
  • Phenylacetates / metabolism
  • Phenylacetates / pharmacology
  • Polymerase Chain Reaction
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / analysis
  • Receptors, Cell Surface / metabolism*
  • Repressor Proteins / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / metabolism*
  • Transformation, Bacterial


  • Cyclic AMP Receptor Protein
  • Escherichia coli Proteins
  • PaaX protein, E coli
  • Phenylacetates
  • RNA, Messenger
  • Receptors, Cell Surface
  • Repressor Proteins
  • Transcription Factors
  • crp protein, E coli
  • DNA
  • Cyclic AMP
  • Penicillin Amidase
  • phenylacetic acid