Topoisomerase VI senses and exploits both DNA crossings and bends to facilitate strand passage
| Autor: | James M. Berger, Timothy J. Wendorff |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
protein-nucleic acid interactions QH301-705.5 Science Structural Biology and Molecular Biophysics Archaeal Proteins Chemical biology type II topoisomerases General Biochemistry Genetics and Molecular Biology Tangle 03 medical and health sciences chemistry.chemical_compound Knot (unit) Adenosine Triphosphate Biochemistry and Chemical Biology A-DNA Biology (General) DNA Cleavage Gene General Immunology and Microbiology biology DNA Superhelical General Neuroscience Topoisomerase General Medicine protein allostery Cell biology DNA topology Protein Subunits 030104 developmental biology ATP-dependent molecular machines DNA Topoisomerases Type II chemistry Structural biology Methanosarcina biology.protein Medicine Nucleic Acid Conformation Other DNA Research Article |
| Zdroj: | eLife eLife, Vol 7 (2018) |
| ISSN: | 2050-084X |
| Popis: | Type II topoisomerases manage DNA supercoiling and aid chromosome segregation using a complex, ATP-dependent duplex strand passage mechanism. Type IIB topoisomerases and their homologs support both archaeal/plant viability and meiotic recombination. Topo VI, a prototypical type IIB topoisomerase, comprises two Top6A and two Top6B protomers; how these subunits cooperate to engage two DNA segments and link ATP turnover to DNA transport is poorly understood. Using multiple biochemical approaches, we show that Top6B, which harbors the ATPase activity of topo VI, recognizes and exploits the DNA crossings present in supercoiled DNA to stimulate subunit dimerization by ATP. Top6B self-association in turn induces extensive DNA bending, which is needed to support duplex cleavage by Top6A. Our observations explain how topo VI tightly coordinates DNA crossover recognition and ATP binding with strand scission, providing useful insights into the operation of type IIB topoisomerases and related meiotic recombination and GHKL ATPase machineries. eLife digest Each human cell contains genetic information stored on approximately two meters of DNA. Like holiday lights in a storage box, packing so much DNA into such a small space leads to its entanglement. This snarled DNA prevents the cell from properly accessing and copying its genes. Type II topoisomerases are a group of enzymes that remove DNA tangles. They attach to one segment of a DNA tangle, cut it in half, remove the knot, and then repair the broken DNA strand. The process requires the proteins to ‘burn’ chemical energy. If topoisomerases make mistakes when they cut and reseal DNA, they could damage genetic information and harm cells. It is still unclear how these proteins recognize DNA tangles and use energy to remove knots instead of adding them. Here, Wendorff and Berger use biochemical approaches to look into topo VI, a type II topoisomerase found in plants and certain single-celled organisms. When DNA is tangled, it forms sharp bends and crossings. Their experiments reveal that topo VI has certain ‘sensors’ that detect where DNA bends, and others that recognize the crossings. Only when both features are present does the enzyme start working and using energy. These sensors act as fail-safes to ensure that topo VI only breaks DNA when it encounters a proper knot, and is not ‘set loose’ on untangled DNA. Future work will look at topo VI at an atom-by-atom level to reveal how exactly the enzymes ‘see’ DNA bends and crossings, and how interactions with the correct type of DNA triggers energy use and DNA untangling. Knowing more about topo VI can help researchers to understand how human and bacterial topoisomerases work. These results could also be generalized to other enzymes, for example those that help the genetic processes at play when sperm and egg cells form. |
| Databáze: | OpenAIRE |
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