Biology subjects

Nanao, M.

Publications and source records attributed to Nanao, M..

3 recordsLinked to original sources

bioRxiv2024

In-situ serial crystallography facilitates 96-well plate structuralanalysis at low symmetry

The advent of serial crystallography has rejuvenated and popularised room temperature X-ray crystal structure determination. Structures determined at physiological temperature reveal protein flexibility and dynamics. In addition, challenging samples (e.g., large complexes, membrane proteins, and viruses) forming fragile crystals, are often difficult to harvest for cryo-crystallography. Moreover, a typical serial crystallography experiment requires a large number of microcrystals, mainly achievable through batch crystallisation. Many medically relevant samples are expressed in mammalian cell-lines, producing a meagre quantity of protein that is incompatible for batch crystallisation. This can limit the scope of serial crystallography approaches. Direct in-situ data collection from a 96-well crystallisation plate enables not only the identification of the best diffracting crystallisation condition, but also the possibility for structure determination at ambient conditions. Here, we describe an in situ serial crystallography (iSX) approach, facilitating direct measurement from crystallisation plates, mounted on a rapidly exchangeable universal plate holder deployed at a microfocus beamline, ID23-2, at the European Synchrotron Radiation Facility (ESRF). We applied our iSX approach on a challenging project, Autotaxin, a therapeutic target expressed in a stable human cell-line, to determine a structure in the lowest symmetry P1 space group at 3.0 [A] resolution. Our in situ data collection strategy provided a complete dataset for structure determination, while screening various crystallisation conditions. Our data analysis reveals that the iSX approach is highly efficient at a microfocus beamline, improving throughput and demonstrating how crystallisation plates can be routinely used as an alternative method of presenting samples for serial crystallography experiments at synchrotrons. SynopsisThe determination of a challenging structure in the P1 space group, the lowest symmetry possible, shows how our in-situ serial crystallography approach expands the application of crystallisation plates as a robust sample delivery method.

biophysics↗

bioRxiv2022

The F-box cofactor UFO redirects the LEAFY floral regulator to novel cis-elements

In angiosperms, flower patterning requires the localized expression of the APETALA3 (AP3) floral homeotic gene involved in petal and stamen development. AP3 is synergistically induced by the master transcription factor (TF) LEAFY (LFY) and the F-box protein UNUSUAL FLORAL ORGANS (UFO), but the molecular mechanism underlying this synergy has remained unknown. Here we show that the connection to ubiquitination pathways suggested by the F-box domain of UFO is mostly dispensable for its function and that UFO instead acts by forming a transcriptional complex with LFY and binds to newly discovered regulatory elements. Cryo-electron microscopy explains how a LFY-UFO complex forms on these novel DNA sites due to direct interaction of UFO with LFY and DNA. Finally, we show that this complex has a deep evolutionary origin, largely predating flowering plants. This work reveals a novel mechanism of an F-box protein in directly modulating the DNA-binding specificity of a master TF.

plant biology↗

bioRxiv2019

Molecular mechanisms of Evening Complex activity in Arabidopsis

The Evening Complex (EC), composed of the DNA-binding protein LUX ARRHYTHMO (LUX) and two additional proteins, EARLY FLOWERING 3 (ELF3) and ELF4, is a transcriptional repressor complex and a core component of the plant circadian clock. In addition to maintaining oscillations in clock gene expression, the EC also participates in temperature and light entrainment and regulates important clock output genes such as PHYTOCHROME INTERACTING FACTOR 4 (PIF4), a key transcription factor involved in temperature dependent plant growth. These properties make the EC an attractive target for altering plant development through targeted mutations to the complex. However, the molecular basis for EC function was not known. Here we show that binding of the EC requires all three proteins and that ELF3 decreases the ability of LUX to bind DNA whereas the presence of ELF4 restores interaction with DNA. To be able to manipulate this complex, we solved the structure of the DNA-binding domain of LUX bound to DNA. Using structure-based design, a LUX variant was constructed that showed decreased in vitro binding affinity but retained specificity for its cognate sequences. This designed LUX allele modulates hypocotyl elongation and flowering. These results demonstrate that modifying the DNA-binding affinity of LUX can be used to titrate the repressive activity of the entire EC, tuning growth and development in a predictable manner.\n\nSignificance StatementCircadian gene expression oscillates over a 24 hr. period and regulates many genes critical for growth and development. In plants, the Evening Complex (EC), a three-protein repressive complex made up of LUX ARRYTHMO, EARLY FLOWERING 3 and EARLY FLOWERING 4, acts as a key component of the circadian clock and is a regulator of thermomorphogenic growth. However, the molecular mechanisms of complex formation and DNA-binding have not been identified. Here we determine the roles of each protein in the complex and present the structure of the LUX DNA-binding domain in complex with DNA. Based on these data, we used structure-based protein engineering to produce a version of the EC with altered in vitro and in vivo activity. These results demonstrate that the EC can be modified to alter plant growth and development at different temperatures in a predictable manner.

plant biology↗