In protein structures, a beta barrel is a beta-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 in many beta-barrels are arranged in an antiparallel fashion. Beta barrel structures are named for resemblance to the barrels used to contain liquids. Most of them are water-soluble proteins and frequently bind hydrophobic ligands in the barrel center, as in lipocalins. Others span cell membranes and commonly found in porins. Porin-like barrel structures are encoded by as many as 2–3% of the genes in Gram-negative bacteria. In many cases, the strands contain alternating polar and non-polar (hydrophilic and hydrophobic) amino acids, so that the hydrophobic residues are oriented into the interior of the barrel to form a hydrophobic core and the polar residues are oriented toward the outside of the barrel on the solvent-exposed surface.
Outer membrane protein (OMP) biogenesis is an essential process for maintaining the bacterial cell envelope and involves the beta-barrel assembly machinery (BAM) for OMP recognition, folding and assembly. In Escherichia coli this function is orchestrated by five proteins: the integral outer membrane protein BamA of the Omp85 superfamily and four associated lipoproteins. Escherichia coli BamA is characterized by a discontinuous β-barrel with impaired β1-β16 strand interactions denoted by only two connecting hydrogen bonds and a disordered C-terminus. The 16-stranded barrel surrounds a large cavity which implies a function in OMP substrate binding and partial folding. Here you can see the crystal structure of BamA protein from Escherichia coli showing the characteristic beta-barrel fold (PDB code: 6FSU)
#immolecular ... #molecularart ... #betabarrel ... #porin ... #betasheet ... #bundle ... #escherichia ... #outermembrane ... #xray
Rendered with @proteinimaging and finished with @corelphotopaint
Outer membrane protein (OMP) biogenesis is an essential process for maintaining the bacterial cell envelope and involves the beta-barrel assembly machinery (BAM) for OMP recognition, folding and assembly. In Escherichia coli this function is orchestrated by five proteins: the integral outer membrane protein BamA of the Omp85 superfamily and four associated lipoproteins. Escherichia coli BamA is characterized by a discontinuous β-barrel with impaired β1-β16 strand interactions denoted by only two connecting hydrogen bonds and a disordered C-terminus. The 16-stranded barrel surrounds a large cavity which implies a function in OMP substrate binding and partial folding. Here you can see the crystal structure of BamA protein from Escherichia coli showing the characteristic beta-barrel fold (PDB code: 6FSU)
#immolecular ... #molecularart ... #betabarrel ... #porin ... #betasheet ... #bundle ... #escherichia ... #outermembrane ... #xray
Rendered with @proteinimaging and finished with @corelphotopaint
