The PDZ domain of OutC and the N-terminal region of OutD determine the secretion specificity of the type II out pathway of Erwinia chrysanthemi

J Mol Biol. 2001 Apr 27;308(2):205-19. doi: 10.1006/jmbi.2001.4594.


The plant pathogens Erwinia chrysanthemi and Erwinia carotovora secrete multiple exoproteins by a type II pathway, the Out system. Secretion in Erwinia is species-specific: exoproteins of one species cannot be secreted by the other. We analysed the role of two components of the Out system, the bitopic inner membrane protein OutC and the secretin OutD, in the specific recognition of secreted proteins. We demonstrated that the PDZ domain of OutC determines its secretion specificity towards certain exoproteins. The secretin is the major determinant of specificity of the Out system: OutD of E. carotovora changes the secretion specificity of E. chrysanthemi and enables it to secrete heterologous exoproteins. Construction of chimeric OutD showed that the N-terminal region is the specificity domain of the secretin. Thus, both the PDZ domain of OutC and the N-terminal region of OutD are required for specific recognition of secreted proteins. Systematic analysis of the secretion of several exoproteins demonstrated that different exoproteins secreted by the Out machinery have different requirement for their presumed targeting signals on OutC and OutD. This strongly indicates that diverse exoproteins possess a variable number of targeting signals which are recognised by different regions of OutC and OutD.

Publication types

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

MeSH terms

  • Amino Acid Motifs
  • Bacterial Outer Membrane Proteins / chemistry*
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Carbonyl Cyanide m-Chlorophenyl Hydrazone / pharmacology
  • Cellulase / metabolism
  • Genetic Complementation Test
  • Pectobacterium carotovorum / drug effects
  • Pectobacterium carotovorum / enzymology
  • Pectobacterium carotovorum / genetics
  • Pectobacterium carotovorum / metabolism
  • Pectobacterium chrysanthemi / drug effects
  • Pectobacterium chrysanthemi / enzymology
  • Pectobacterium chrysanthemi / genetics
  • Pectobacterium chrysanthemi / metabolism*
  • Polysaccharide-Lyases / metabolism
  • Protein Processing, Post-Translational / drug effects
  • Protein Sorting Signals
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Deletion
  • Substrate Specificity


  • Bacterial Outer Membrane Proteins
  • OutC protein, bacteria
  • OutD protein, Erwinia chrysanthemi
  • Protein Sorting Signals
  • Recombinant Fusion Proteins
  • Carbonyl Cyanide m-Chlorophenyl Hydrazone
  • Cellulase
  • Polysaccharide-Lyases
  • pectate lyase