The work, sponsored by the American Cancer Society, appears in the Dec. 8 issue of the journal Structure. It could aid drug makers in designing targeted therapies that block cancer cells from multiplying.
"All cancers are marked by some form of DNA replication gone awry, so a basic understanding of DNA replication is of paramount importance to those designing cancer-fighting drugs," said lead author Yousif Shamoo, assistant professor of biochemistry and cell biology. "In addition, almost every form of life including bacteria use a variant of the protein that we studied, and we believe the work may also aid drug makers who are developing new forms of antibiotics."
In the study, Shamoo and graduate student John Bruning used x-ray crystallography and isothermal titration calorimetry to determine the structures of two variants of a protein called Human Proliferating Cellular Nuclear Antigen, or PCNA.
PCNA is a member of the "sliding clamp" family of proteins, which are so-named because of their unique shape and function. Sliding clamps are ring-shaped proteins that slide along strands of DNA. DNA is fed through the hole in the center, and the PCNA acts as a docking mechanism for other proteins that need to interact with the DNA to make repairs or copies or to take part in other genetically regulated tasks. Genes that code for sliding clamp proteins are present in all forms of life except for some viruses.
In humans, at least a dozen proteins are known to dock with PCNA. Each of them docks with PCNA by inserting a kind of key known as a PCNA-interacting protein, or "PIP-box," which binds chemically to the PCNA and holds the docked
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Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
7-Dec-2004