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http://hdl.handle.net/2445/116023
Title: | DNA structure directs positioning of the mitochondrial genome packaging protein Abf2p. |
Author: | Chakraborty, Arka Lyonnais, Sébastien Battistini, Federica Hospital Gasch, Adam Medici, Giorgio Prohens López, Rafael Orozco López, Modesto Vilardell, Josep Solà, Maria |
Keywords: | ADN mitocondrial Adenina Genomes Mitochondrial DNA Adenine Genomes |
Issue Date: | 28-Nov-2016 |
Publisher: | Oxford University Press |
Abstract: | The mitochondrial genome (mtDNA) is assembled into nucleo-protein structures termed nucleoids and maintained differently compared to nuclear DNA, the involved molecular basis remaining poorly understood. In yeast (Saccharomyces cerevisiae), mtDNA is a ∼80 kbp linear molecule and Abf2p, a double HMG-box protein, packages and maintains it. The protein binds DNA in a non-sequence-specific manner, but displays a distinct 'phased-binding' at specific DNA sequences containing poly-adenine tracts (A-tracts). We present here two crystal structures of Abf2p in complex with mtDNA-derived fragments bearing A-tracts. Each HMG-box of Abf2p induces a 90° bend in the contacted DNA, causing an overall U-turn. Together with previous data, this suggests that U-turn formation is the universal mechanism underlying mtDNA compaction induced by HMG-box proteins. Combining this structural information with mutational, biophysical and computational analyses, we reveal a unique DNA binding mechanism for Abf2p where a characteristic N-terminal flag and helix are crucial for mtDNA maintenance. Additionally, we provide the molecular basis for A-tract mediated exclusion of Abf2p binding. Due to high prevalence of A-tracts in yeast mtDNA, this has critical relevance for nucleoid architecture. Therefore, an unprecedented A-tract mediated protein positioning mechanism regulates DNA packaging proteins in the mitochondria, and in combination with DNA-bending and U-turn formation, governs mtDNA compaction. |
Note: | Reproducció del document publicat a: https://doi.org/10.1093/nar/gkw1147 |
It is part of: | Nucleic Acids Research, 2016, vol. 45, num. 2, p. 951-967 |
URI: | http://hdl.handle.net/2445/116023 |
Related resource: | https://doi.org/10.1093/nar/gkw1147 |
ISSN: | 0305-1048 |
Appears in Collections: | Articles publicats en revistes (Bioquímica i Biomedicina Molecular) Articles publicats en revistes (Institut de Recerca Biomèdica (IRB Barcelona)) |
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