A locus coding for putative non-ribosomal peptide/polyketide synthase functions is mutated in a swarming-defective Proteus mirabilis strain

Mol Gen Genet. 1997 Jan 27;253(4):415-27. doi: 10.1007/s004380050339.


We describe a large bacterial locus that, unusually, encodes components typically required for both the non-ribosomal synthesis of peptides and also polyketide/fatty acid synthase function. Two tandem ABC transporter genes in this putative nrp (non-ribosomal peptide/polyketide) operon suggest that the principal product may be secreted. Immediately distal to the nrp operon is a gene, irpP, encoding a small peptide similar to the Bacillus ComX pheromone that in its mature, extracellular form increases expression of unlinked non-ribosomal peptide synthesis genes. Transcription of both the nrp operon and irpP was up-regulated in iron-limiting culture conditions, consistent with the presence of a putative Fur repressor-binding site 5' of irpP. The locus was isolated from Proteus mirabilis as the site of a TnphoA insertion causing impaired swarm cell differentiation and an aberrant swarming pattern. The mutation was in one of the transporter genes, but a comparable swarming defect resulted from interposon disruption of the putative nrp synthetase gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • Amino Acid Sequence
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Proteins*
  • Base Sequence
  • Gene Expression Regulation, Bacterial
  • Iron / metabolism
  • Iron-Binding Proteins
  • Molecular Sequence Data
  • Movement
  • Multienzyme Complexes / chemistry
  • Multienzyme Complexes / genetics*
  • Mutation
  • Open Reading Frames
  • Operon*
  • Peptide Synthases / chemistry
  • Peptide Synthases / genetics*
  • Periplasmic Binding Proteins
  • Proteus mirabilis / enzymology
  • Proteus mirabilis / genetics*
  • Proteus mirabilis / physiology
  • Transcription, Genetic


  • ATP-Binding Cassette Transporters
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Iron-Binding Proteins
  • Multienzyme Complexes
  • Periplasmic Binding Proteins
  • Iron
  • Peptide Synthases
  • non-ribosomal peptide synthase