Los Angeles, Calif. (June 27, 2011) Why is antibody diversity important? Think about it like this, said Myron Goodman, who is an author on the paper: "Why don't you die when I sneeze? It's because you have a powerful immune system. And the way to get a decent immune system is for your body to have a way to respond to insults it has never seen before."
Random patterns of deamination by the enzyme activation-induced deoxycytidine deaminase (AID) are the key to generating antibody diversity, a crucial component to a healthy immune system, according to a new study by researchers at the USC Dana and David Dornsife College of Letters, Arts and Sciences. The paper, "An Analysis of a Single-stranded DNA Scanning Process in which AID Deaminates C to U Haphazardly and Inefficiently to Ensure Mutational Diversity," was published in The Journal of Biological Chemistry.
Having variation in the types of antibodies produced by your body gives it a fighting chance to respond to those "insults." Antibodies protect against invasion by antigens such as bacteria or viruses by locating them in the body and neutralizing them. To do that, antibodies must bind to antigens. The more variation in the types of antibodies produced by the body, the more likely they will be able to bind to and fight off antigens, which come in many forms.
To create antibody diversity, mutations must occur in the variable region of immunoglobulin genes, the region where antibodies bind to invaders. Generating those mutations has to be a really random process according to Goodman, professor of biological sciences and chemistry in USC Dornsife. This is where AID steps in.
Goodman and his colleagues monitored the actions of AID as it scanned single-stranded DNA or transcribed double-stranded DNA. The enzyme essentially moves back and forth along the DNA strand and sporadically deaminates, or converts, cytosine to uracil triggering a mutation in tri-nucleotide motifs
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University of Southern California