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Bacterial microcompartments are widespread, organelle-like structures that are made of a protein shell that surrounds and encloses various enzymes. provide a further level of organization; they are compartments within bacteria that are surrounded by polyhedral protein shells, rather than by lipid membranes. These "polyhedral organelles ...
As in other organisms, the bacterial cell wall provides structural integrity to the cell. In prokaryotes, the primary function of the cell wall is to protect the cell from internal turgor pressure caused by the much higher concentrations of proteins and other molecules inside the cell compared to its external environment.
Most of them are water-soluble outer membrane proteins and frequently bind hydrophobic ligands in the barrel center, as in lipocalins. Others span cell membranes and are commonly found in porins. Porin-like barrel structures are encoded by as many as 2–3% of the genes in Gram-negative bacteria. [1]
The first structure of a bacterial microcompartment shell, determined by X-ray crystallography and cryo-electron microscopy [1] contains representatives of each of the shell protein types: BMC-P, BMC-H and BMC-T, in both its trimer (upper right) and dimer of trimer (lower right), forms.
Schematic diagram of the 2D structure of aquaporin 1 depicting the six transmembrane alpha-helices and the five interhelical loop regions A-E The 3D structure of aquaporin Z highlighting the 'hourglass'-shaped water channel that cuts through the center of the protein. Aquaporin proteins are composed of a bundle of six transmembrane α-helices ...
The general secretion (Sec) involves secretion of unfolded proteins that first remain inside the cells. In Gram-negative bacteria, the secreted protein is sent to either the inner membrane or the periplasm. But in Gram-positive bacteria, the protein can stay in the cell or is mostly transported out of the bacteria using other secretion systems.
Ribbon diagram of myoglobin bound to haem (sticks) and oxygen (red spheres) (Ribbon diagrams, also known as Richardson diagrams, are 3D schematic representations of protein structure and are one of the most common methods of protein depiction used today. The ribbon depicts the general course and organization of the protein backbone in 3D and ...
[1] [2] The S-layers of both archaea and bacteria consists of a monomolecular layer composed of only one (or, in a few cases, two) identical proteins or glycoproteins. [3] This structure is built via self-assembly and encloses the whole cell surface. Thus, the S-layer protein can represent up to 15% of the whole protein content of a cell. [4]