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M protein is a virulence factor that can be produced by certain species of Streptococcus. [1] Viruses, parasites and bacteria are covered in protein and sugar molecules that help them gain entry into a host by counteracting the host's defenses. One such molecule is the M protein produced by certain streptococcal bacteria.
This does not include proteins synthesized due to viral infection, but may include those synthesized by commensal bacteria within the intestines. Proteins that are not created within the body of the organism of interest, but nevertheless enter through the bloodstream, a breach in the skin, or a mucous membrane, may be designated as “non-self ...
An S-layer (surface layer) is a cell surface protein layer found in many different bacteria and in some archaea, where it serves as the cell wall. All S-layers are made up of a two-dimensional array of proteins and have a crystalline appearance, the symmetry of which differs between species.
Bacteria often produce capsules made of proteins or sugars that coat their cells and interfere with phagocytosis. [107] Some examples are the K5 capsule and O75 O antigen found on the surface of Escherichia coli , [ 111 ] and the exopolysaccharide capsules of Staphylococcus epidermidis . [ 112 ]
Bacteria produce various adhesins including lipoteichoic acid, trimeric autotransporter adhesins and a wide variety of other surface proteins to attach to host tissue. Capsules, made of carbohydrate, form part of the outer structure of many bacterial cells including Neisseria meningitidis .
The M protein found on some serotypes is also able to prevent opsonization by binding to fibrinogen. [2] However, the M protein is also the weakest point in this pathogen's defense, as antibodies produced by the immune system against M protein target the bacteria for engulfment by phagocytes. M proteins are unique to each strain, and ...
The previously mentioned protein A, as well as clumping factor, are surface proteins that allow the bacteria to bind to host cells. [20] [7] S. pseudintermedius has been found to produce biofilms, an extracellular matrix of protein, DNA, and polysaccharide, which aids the bacteria in avoiding the host immune system and resisting drugs. [6]
Protein A is a 42 kDa surface protein originally found in the cell wall of the bacteria Staphylococcus aureus. It is encoded by the spa gene and its regulation is controlled by DNA topology, cellular osmolarity, and a two-component system called ArlS-ArlR. It has found use in biochemical research because of its ability to bind immunoglobulins ...