Klebsiella pneumoniae and Streptococcus pneumoniae are two bacteria who are encapsulated, that means that they are surrounded by an envelope. This capsule is critical to their pathogenicity since it protects them from the phagocytes of the human immune system. Certain proteins located on the surface of their capsule prevent the phagocytic cell from adhering to the bacteria and engulfing it.
Like all enzymes, a restriction enzyme works by shape-to-shape matching. When it comes into contact with a DNA sequence with a shape that matches a part of the enzyme, called the recognition site, it wraps around the DNA and causes a break in both strands of the DNA molecule.
