The outer membrane efflux protein is a
protein family member that forms trimeric (three-piece) channels allowing the export of a variety of substrates in
gram-negative bacteria
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the Crystal violet, crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelo ...
. Each efflux protein is composed of two repeats. The trimeric channel is composed of a 12-stranded
beta-barrel
In protein structures, a beta barrel (β barrel) is a beta sheet (β sheet) composed of tandem repeats that twists and coils to form a closed toroidal structure in which the first strand is bonded to the last strand (hydrogen bond). Beta-strands ...
that spans the
outer membrane, and a long tail helical barrel that spans the
periplasm
The periplasm is a concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the bacterial outer membrane called the ''periplasmic space'' in Gram-negative (more accurately "diderm") bacteria. Using cryo-electron micros ...
.
Examples include the ''
Escherichia coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...
'' TolC outer membrane protein, which is required for proper expression of outer membrane protein genes; the Rhizobium nodulation protein; and the Pseudomonas FusA protein, which is involved in resistance to
fusaric acid
Fusaric acid is a picolinic acid derivative and an antibiotic (wilting agent) first isolated from the fungus '' Fusarium heterosporium''.
It is typically isolated from various Fusarium species, and has been proposed for a various therapeutic appl ...
.
References
*
Protein domains
Protein families
Outer membrane proteins
{{membrane-protein-stub