Biology:Protein K (porin)
Structure
Proteinase K has a catalytic triad of Ser 224, His 69, and Asp 39. Two peptide chains recognize substrates, 99-104 and 132–136. There is also a cysteine free near His 69.[1]
Protein K is a porin expressed in some pathogenic strains of E. coli bacteria. It has a molecular weight of about 40 kDa and is localized to the outer membrane, through which it allows both inorganic and organic ions to pass. The addition of Protein K in the outer membrane proven to cause an increased rate of uptake of nutrients and a faster growth rate relative to the parental porin- strain.[2]
The strains in which protein K has been identified are encapsulated, or surrounded by a poly-sialic acid capsule that renders them more resistant to phagocytosis by cells in the immune system.
References
- ↑ "Introduction into Proteinase K | GoldBio" (in en-US). https://www.goldbio.com/articles/article/Intro-Into-Pro-K.
- ↑ Sutcliffe, J; Blumenthal, R; Walter, A; Foulds, J (1983). "Escherichia coli outer membrane protein K is a porin". Journal of Bacteriology 156 (2): 867–872. doi:10.1128/jb.156.2.867-872.1983. ISSN 0021-9193. PMID 6313620. PMC 217905. http://dx.doi.org/10.1128/jb.156.2.867-872.1983.
- Whitfield C, Hancock RE, Costerson JW. (1983). Outer membrane protein K of Escherichia coli: purification and pore-forming properties in lipid bilayer membranes. J Bacteriol 156(2): 873-879
- Sutcliffe J, Blumenthal R, Walter A, Foulds J. (1983). Escherichia coli outer membrane protein K is a porin. J Bacteriol 156(2): 867-872
- Bliss JM, Solver RP. (1996). Coating the surface: a model for expression of capsular polysialic acid in Escherichia coli K1. Mol Microbiol 21:221.
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