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Members of the Outer membrane phospholipase A (OMPLA) family are integral membrane phospholipases, present in many Gram-negative bacteria with a broad substrate specificity. The role of OMPLA has been most thoroughly studied in Escherichia coli, where it participates in the secretion of colicins. The three-dimensional structure of OmplA of Escherichia coli has been determined, revealing a 12-stranded antiparallel ß-barrel with a convex and a flat side. The active site residues are exposed at the exterior of the flat face of the barrel. The activity of the enzyme is calcium-dependent and regulated by reversible dimerisation. Dimer interactions occur exclusively in the membrane-embedded parts of the flat side of the barrel, with polar residues embedded in an apolar environment forming the key interactions. The active site (Asn-156-His-142-Ser-144) is located at the exterior of the barrel, at the outer leaflet side of the membrane. The phospholipids of the inner leaflet are believed to be presented to the active site of OMPLA by perturbation of the membrane causing the formation of non-bilayer structures and finally leading to the formation of the active dimer.
Bacteriocin release protein triggers dimerization of outer membrane phospholipase A in vivo
J Bacteriol. 1999 May;181(10):3281-3. doi: 10.1128/JB.181.10.3281-3283.1999.
Bacterial phospholipase A: structure and function of an integral membrane phospholipase
Biochim Biophys Acta. 2000 Oct 31;1488(1-2):91-101. doi: 10.1016/s1388-1981(00)00113-x.
Detergent organisation in crystals of monomeric outer membrane phospholipase A
J Struct Biol. 2003 Feb;141(2):122-31. doi: 10.1016/s1047-8477(02)00579-8.
Structural biology of membrane-intrinsic beta-barrel enzymes: sentinels of the bacterial outer membrane
Biochim Biophys Acta. 2008 Sep;1778(9):1881-96. doi: 10.1016/j.bbamem.2007.07.021. Epub 2007 Aug 11.
Structural evidence for dimerization-regulated activation of an integral membrane phospholipase
Nature. 1999 Oct 14;401(6754):717-21. doi: 10.1038/44890.
Structural investigations of calcium binding and its role in activity and activation of outer membrane phospholipase A from Escherichia coli
J Mol Biol. 2001 Jun 1;309(2):477-89. doi: 10.1006/jmbi.2001.4675.
Structural investigations of the active-site mutant Asn156Ala of outer membrane phospholipase A: function of the Asn-His interaction in the catalytic triad
Protein Sci. 2001 Oct;10(10):1962-9. doi: 10.1110/ps.17701.
|Proteins in this family with 3D-structure|