July 2008: Santa Cruz, University of California
A surprising type of gene regulation found in mammals under the influence of RIBOZYME
A ribozyme, as the name implies, is an RNA molecule that can catalyze a chemical reaction. Although, RNA is mostly known to play a role in the encoding of genetic info, leaving the catalysis of biological reactions up to enzymes made out of protein. Now, scientists are discovering that RNA might be taking part in both.
The hammerhead ribozyme, previously known to be associated with viroids “plant viruses”, has been found in mice, rats, horses, and other mammals, embedded within certain genes & controlling their expression. Example of such genes are those involved in the body’s immune response & metabolism of bone. In these genes, the mRNA contains sequences that form a hammerhead ribozyme.
The hammerhead ribozyme is a self-cleaving molecule that cuts itself in two. That way, the protein translation is prevented & therefore, no gene expression takes place. To turn the process back on, the self-cleaving action is stopped. Exactly what shuts off the ribozyme action is not known, but assumed to be there.
Two interesting points come up now:
1. The hammerhead ribozyme sequences first appeared in the genomes of rat & mice and then turned up in other mammals but was not found in the corresponding human genes which suggests that a different mechanism DOES exist regulating those genes in humans.
2. The genes, being regulated by a hammerhead ribozyme, are involved in the immune response & in bone metabolism. Such finding can be targeted by the pharmaceutical industry to combat certain autoimmune diseases & bone disorders, which offers potential for better & safter healthcare treatment in the future.
Tags: gene, ribozyme, RNA, sequence
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I have once read about ribozymes. In addition to their catalytic process in cleaving RNA, they do have an aminotransferase activity, where they catayze peptide bond formation. The molecules of ribozymes are found on the surface of ribosome.