A major outer-membrane protein functions as a porin in Haemophilus influenzae

J Gen Microbiol. 1987 May;133(5):1273-7. doi: 10.1099/00221287-133-5-1273.


Porins are pore-forming outer-membrane proteins which serve as a non-specific pathway for the entry of hydrophilic molecules into Gram-negative bacteria. We studied four strains of Haemophilus influenzae that had decreased permeability to chloramphenicol associated with diminished quantities of a 40 kDa major outer-membrane protein. Isogenic pairs of organisms containing and lacking this protein were compared. The latter strains grew more slowly and were less permeable to sucrose and raffinose. They were also more resistant to multiple hydrophilic antibiotics than an isogenic strain containing the 40 kDa protein and were less permeable to penicillin G and chloramphenicol. We conclude that the 40 kDa outer-membrane protein functions as a porin in H. influenzae.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Outer Membrane Proteins / metabolism*
  • Cell Membrane Permeability / drug effects
  • Drug Resistance, Microbial
  • Haemophilus influenzae / drug effects
  • Haemophilus influenzae / growth & development*
  • Ion Channels / drug effects
  • Oligosaccharides / metabolism
  • Penicillin G / pharmacology
  • Penicillin Resistance
  • Porins


  • Anti-Bacterial Agents
  • Bacterial Outer Membrane Proteins
  • Ion Channels
  • Oligosaccharides
  • Porins
  • Penicillin G