SMALL-ANGLE NEUTRON SCATTERING UNIQUELY PROBES GENE REGULATORY PROTEIN/DNA COMPLEXES.Scientists at the NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. Center for Neutron Research (NCNR NCNR NIST Center for Neutron Research NCNR Non-Cancelable, Non-Returnable NCNR National Center for Nursing Research (NIH) NCNR Nearest Common Node Rerouting (ATM) NCNR National Center for Neutron Research ) are using small-angle neutron scattering Small angle neutron scattering (SANS) is a laboratory technique, similar to the often complementary techniques of small angle X-ray scattering (SAXS) and light scattering. These are particularly useful because of the dramatic increase in forward scattering that occurs at phase to obtain unique information about the structure of gene regulatory protein/DNA complexes in solution. Gene regulatory proteins regulatory proteins 1. proteins which regulate the contraction of muscle by controlling the interaction of myosin and actin. Calcium is an essential component of this reaction. The two proteins are troponin and tropomyosin. 2. control gene expression in developmental and cellular processes of many organisms. Some are activators, turning genes on and some are repressors, turning genes off. All gene regulatory proteins recognize and bind specific DNA sequences. The binding of gene regulatory proteins to DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. often results in a deformation of the DNA. There also has been recent indirect evidence that the proteins undergo a structural change as well upon DNA binding. Small-angle neutron scattering (SANS) is currently being used at the NCNR to study the structural changes in both the DNA and protein components of DNA/gene regulatory protein complexes. The goal is to better understand the interactions between DNA and proteins in these important biological systems. SANS is ideal for studying protein/DNA complexes since the neutron scattering strengths of DNA and protein differ with respect to each other. By measuring the complex in solutions containing different amounts of [D.sub.2]O, with respect to [H.sub.2]O, different structural components can be highlighted, while others are suppressed. By measuring the protein/DNA complex under a sufficient number of solvent conditions, the structure of the two components can be separately determined, even though both components are bound together as one complex! Thus, SANS allows a unique determination of the structure of the individual components in the complex. Recent SANS experiments have confirmed that the gene activator protein, cyclic AMP cyclic AMP: see adenosine monophosphate. receptor protein (CRP C-reactive protein (CRP) A protein present in blood serum in various abnormal states, like inflammation. Mentioned in: Pelvic Inflammatory Disease CRP, n.pr See C-reactive protein. ), undergoes a significant structural, or conformational, change in solution upon DNA binding. Furthermore, the regions of the protein that undergo the conformational change contain the binding site for RNA polymerase, which plays a crucial role in the early stages of protein synthesis. This structural change may be necessary in order for CRP to interact with RNA polymerase during this process. Further SANS studies are under way on other protein/DNA complexes that play a role in gene regulation. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion