Escherichia coli target specificity

The capacity of pathogenic bacteria to adhere to mucosal membranes has been exploited in the modification of new mucoadhesive polymers. The ability of bacteria to adhere to a specific target is rooted from particular cell-surface components or appendages, known as fimbriae, which promote adhesion to other cells or inanimate surfaces. Fimbriae are extracellular, long thread-like protein polymers of bacteria that play a major role in many diseases. It has been reported that Escherichia coli adheres specifically to the lymphoid follicle epithelium of the ileal Peyer s patch in rabbits. Similarly, different staphylococci possess the ability to adhere specifically to the surface of mucus gel layers and not mucus-free surfaces. Thus, polymers have been modified by the attachment of these fimbriae to enhance mucoadhesion. An attachment protein derived from E. coli, K99-fimbriae, has been covalently attached to polyacrylic acid networks in an attempt to provide a novel polymer with enhanced adhesive properties (Figure 52.7). ... 

ChIP-chop allows one to determine if the DNA that is associated with an antigen of interest is highly CpG-methylated. The Escherichia coli enzyme McrBC is used to hydrolyze ( chop ) the DNA that is methylated specifically at purine/cytosine sites. Hydrolysis within the target DNA sequence prevents detection of the DNA by PCR [24]. 

Streuli, M., A. Hall, W. BoU, WE. Stewart, 2nd, S. Nagata, and C. Weissmann, Target cell specificity of two species of human interferon-alpha produced in Escherichia coli and of hybrid molecules derived from them. Proc Natl Acad Sci USA, 1981.78(5) 2848-52. 

M. S. Kang, D.B. Ha, C.H. Chung, The P-1 Reactive Site Methionine Residue of Ecotin Is Not Cmcial for Its Specificity on Target Proteases - a Potent Inhibitor of Pancreatic Serine Proteases from Escherichia Coli. J. Biol. Chem. 1994,... 

Tempbn, M F, Edwards, D H, Holtje, J-V, A murein hydrolase is the specific target of bulgecin in Escherichia coli, J. Biol. Chem., 267, 20039-20043, 1992. 

A unique biochemical target in the HIV-1 replication cycle was revealed when HIV protease was cloned and expressed " in Escherichia coli. HIV protease is an enzyme that cleaves gag-pro propeptides to yield active enzymes that function in the maturation and propagation of new virus. The catalytically active protca.se is a. symmetric dimer of two identical 99 amino acid subunits, each contributing the triad Asp-Thr-Gly to the active site." The homodimer is unlike monomeric asparlyl protea.ses (renin, pepsin, cathep-sin D). which also have different. substrate specificities. The designs of. some inhibitors for HIV-1 protease exploit the C2 symmetry of the enzyme. HIV-1 protease has active site speclnc ity for the triad Tyr-Phe-Pro in the unit Ser-(Thr)-Xaa-Xaa-Tyr-Phc-Pm. whenr Xaa is an arbitrary amino acid. 

Figure 7 Cloning by restriction digest and ligation. Both the PCR-amplified gene of interest and the target vector are digested with the same restriction enzymes (or with enzymes that produce compatible ends). The short section of overhanging sequence (called sticky ends ) are complementary to each other. The digested DNAs are mixed, treated with ligase, and transformed into a suitable Escherichia coli host strain to produce a new recombinant DNA molecule with the gene of interest specifically inserted into a host vector.

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