Microbiology and Immunology

Prions WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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Porins also have relevance in the antibiotic resistanceof

bacteria, particularly Pseudomonas aerugionsa, which is the

cause of lung infections in those afflicted with cystic fibrosis,

and can cause so-called “opportunistic infections” in those

whose immune systemis impaired. For example, the porin

designated OprD is specifically utilized for the diffusion of the

antibiotic imipenem into the bacterium. Imipenem resistance

is associated with an alteration in the three-dimensional struc-

ture of OprD such that imipenem is excluded from entering the

bacterium. The resistance of a number of clinical isolates of

Pseudomonas aeruginosais the result of porin alteration.

Knowledge of the molecular nature of the alterations will help

in the design of antibioticsthat overcome the channel barrier.

See alsoBacterial membranes and cell wall; Protein export

Three-dimensional computer model of a protein molecule of matrix porin found in E. colibacteria.

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