title: PorA represents the major cell wall channel of the Gram-positive bacterium Corynebacterium glutamicum.
abstract: The cell wall of the gram-positive bacterium Corynebacterium glutamicum contains a channel (porin) for the passage of hydrophilic solutes. The channel-forming polypeptide PorA is a 45-amino-acid acidic polypeptide with an excess of four negatively charged amino acids, which is encoded by the 138-bp gene porA. porA was deleted from the chromosome of C.glutamicum wild-type strain ATCC 13032 to obtain mutant ATCC 13032deltaporA. Southern blot analysis demonstrated that porA was deleted. Lipid bilayer experiments revealed that PorA was not present in the cell wall of the mutant strain. Searches within the known chromosome of C. glutamicum by using National Center for Biotechnology Information BLAST and reverse transcription-PCR showed that no other PorA-like protein is encoded on the chromosome or is expressed in the deletion strain. The porA deletion strain exhibited slower growth and longer growth times than the C. glutamicum wild-type strain. Experiments with different antibiotics revealed that the susceptibility of the mutant strain was much lower than that of the wild-type C. glutamicum strain. The results presented here suggest that PorA represents a major hydrophilic pathway through the cell wall and that C. glutamicum contains cell wall channels which are not related to PorA.
authors.affiliation: Lehrstuhl für Biotechnologie, Biozentrum der Universität Würzburg, D-97074 Würzburg, Germany.
authors.forename: Noelia
authors.initials: N
authors.lastname: Costa-Riu
authors.forename: Andreas
authors.initials: A
authors.lastname: Burkovski
authors.forename: Reinhard
authors.initials: R
authors.lastname: Krämer
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D001692:Biological Transport; D015139:Blotting, Southern; D002463:Cell Membrane Permeability; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D003352:Corynebacterium / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D017353:Gene Deletion; D007473:Ion Channels / Q000502:physiology*; D008051:Lipid Bilayers; D008969:Molecular Sequence Data; D018272:Porins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D007473:Ion Channels; D008051:Lipid Bilayers; C422458:PorA protein, Corynebacterium glutamicum; D018272:Porins