scholarly journals Implementation of single molecule FRET for visualizing intramolecular movement in CRISPR-Cas9

2020 ◽  
Author(s):  
Haruka Narita ◽  
Hiroshi Ebata ◽  
Karibu Sakai ◽  
Katsuhiko Minami ◽  
Sotaro Uemura ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Dna Sequence ◽  
Single Molecule ◽  
Fluorescence Anisotropy ◽  
Molecular Basis ◽  
Catalytic Process ◽  
Single Molecule Fret ◽  
Protospacer Adjacent Motif ◽  
A Genome ◽  
Cas9 Protein

SHORT ABSTRACTThis paper summarizes how to visualize the flexible inter-domain movements of CRISPR-associated protein Cas9 using single molecule FRETLONG ABSTRACTThe CRISPR-associated protein Cas9 is widely used as a genome editing tool because of its ability to be programmed to cleave any DNA sequence that is followed by a protospacer adjacent motif. The continuing expansion of Cas9 technologies has stimulated studies regarding the molecular basis of the Cas9 catalytic process. Here we summarize methods for single molecule FRET (smFRET) to visualize the inter-domain movements of Cas9 protein. Our measurements and analysis demonstrate flexible and reversible movements of the Cas9 domains. Such flexible movements allow Cas9 to adopt transient conformations beyond those solved by crystal structures and play important roles in the Cas9 catalytic process. In addition to the smFRET measurement itself, to obtain precise results, it is necessary to validate Cas9 catalytic activity. Also, fluorescence anisotropy data are required to interpret smFRET data properly. Thus, in this paper, we describe the details of these important additional experiments for smFRET measurements.

scholarly journals Molecular basis of ubiquitin-specific protease 8 autoinhibition by the WW-like domain

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Keijun Kakihara ◽  
Kengo Asamizu ◽  
Kei Moritsugu ◽  
Masahide Kubo ◽  
Tetsuya Kitaguchi ◽  
...  
Keyword(s):  
Single Molecule ◽  
Membrane Trafficking ◽  
Cushing’S Disease ◽  
Molecular Basis ◽  
Binding Pocket ◽  
Cushing's Disease ◽  
Binding Motif ◽  
Single Molecule Fret ◽  
Specific Protease ◽  
Ubiquitin Specific Protease

AbstractUbiquitin-specific protease 8 (USP8) is a deubiquitinating enzyme involved in multiple membrane trafficking pathways. The enzyme activity is inhibited by binding to 14-3-3 proteins. Mutations in the 14-3-3-binding motif in USP8 are related to Cushing’s disease. However, the molecular basis of USP8 activity regulation remains unclear. This study identified amino acids 645–684 of USP8 as an autoinhibitory region, which might interact with the catalytic USP domain, as per the results of pull-down and single-molecule FRET assays performed in this study. In silico modelling indicated that the region forms a WW-like domain structure, plugs the catalytic cleft, and narrows the entrance to the ubiquitin-binding pocket. Furthermore, 14-3-3 inhibited USP8 activity partly by enhancing the interaction between the WW-like and USP domains. These findings provide the molecular basis of USP8 autoinhibition via the WW-like domain. Moreover, they suggest that the release of autoinhibition may underlie Cushing’s disease due to USP8 mutations.

scholarly journals Structural basis of recognition and destabilization of histone H2B ubiquitinated nucleosome by DOT1L histone H3 Lys79 methyltransferase

2018 ◽  
Author(s):  
Seongmin Jang ◽  
Chanshin Kang ◽  
Han-Sol Yang ◽  
Taeyang Jung ◽  
Hans Hebert ◽  
...  
Keyword(s):  
Single Molecule ◽  
Cross Talk ◽  
Molecular Basis ◽  
Histone H3 ◽  
Structural Basis ◽  
Histone H2b ◽  
Single Molecule Fret ◽  
Catalytic Function ◽  
Histone H3 Methylation ◽  
Hydrophobic Helix

AbstractDOT1L is a histone H3 Lys79 methyltransferase whose activity is stimulated by histone H2B Lys120 ubiquitination, suggesting cross-talk between histone H3 methylation and H2B-ubiquitination. Here, we present cryo-EM structures of DOT1L complex with unmodified and H2B-ubiquitinated nucleosomes, showing that DOT1L recognizes H2B-ubiquitin and the H2A/H2B acidic patch through a C-terminal hydrophobic helix and an arginine anchor in DOT1L respectively. Furthermore, the structures combined with single-molecule FRET experiment show that H2B-ubiquitination enhances a non-catalytic function of DOT1L destabilizing nucleosome. These results establish the molecular basis of the cross-talk between H2B ubiquitination and H3 Lys79 methylation as well as nucleosome destabilization by DOT1L.

scholarly journals The molecular basis of ubiquitin-specific protease 8 autoinhibition by the WW-like domain

2021 ◽  
Author(s):  
Keijun Kakihara ◽  
Kengo Asamizu ◽  
Kei Moritsugu ◽  
Masahide Kubo ◽  
Tetsuya Kitaguchi ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Single Molecule ◽  
Membrane Trafficking ◽  
Molecular Basis ◽  
Binding Pocket ◽  
Binding Motif ◽  
Deubiquitinating Enzyme ◽  
Single Molecule Fret ◽  
Specific Protease ◽  
Ubiquitin Specific Protease

Ubiquitin-specific protease 8 (USP8) is a deubiquitinating enzyme involved in multiple membrane trafficking pathways. The enzyme activity is inhibited by binding to 14-3-3 proteins, and mutations of the 14-3-3 binding motif in USP8 are related to Cushing′s disease. However, the molecular basis of USP8 enzyme activity regulation remains unclear. Here, we identified amino acids 645–684 of USP8 as an autoinhibitory region, which our pull-down and single-molecule FRET assay results suggested interacts with the catalytic USP domain. In silico modelling indicated that the region forms a WW-like domain structure, plugs the catalytic cleft, and narrows the entrance to the ubiquitin-binding pocket. Furthermore, 14-3-3 was found to inhibit USP8 enzyme activity partly by enhancing the interaction between the WW-like and USP domains. These findings provide the molecular basis of USP8 autoinhibition via the WW-like domain. Moreover, they suggest that the release of autoinhibition may underlie Cushing′s disease caused by USP8 mutations.

scholarly journals Real-time observation of DNA recognition and rejection by the RNA-guided endonuclease Cas9

2016 ◽  
Author(s):  
Digvijay Singh ◽  
Samuel H. Sternberg ◽  
Jingyi Fei ◽  
Jennifer A. Doudna ◽  
Taekjip Ha
Keyword(s):  
Real Time ◽  
Single Molecule ◽  
Dna Cleavage ◽  
Genome Engineering ◽  
Dissociation Rate ◽  
Stable Complex ◽  
Guide Rna ◽  
Single Molecule Fret ◽  
Protospacer Adjacent Motif ◽  
Time Observation

Binding specificity of Cas9-guide RNA complexes to DNA is important for genome engineering applications, but how mismatches influence target recognition and rejection kinetics is not well understood. We used single-molecule FRET to probe real-time interactions between Cas9-RNA and DNA targets. The bimolecular association rate is only weakly dependent on sequence, but the dissociation rate greatly increases from < 0.006 s-1 to > 2 s-1 upon introduction of mismatches proximal to the protospacer adjacent motif (PAM), demonstrating that mismatches encountered early during heteroduplex formation induce rapid rejection of off-target DNA. In contrast, PAM-distal mismatches up to 12 base pairs in length, which prevent DNA cleavage, still allow the formation of a stable complex (off-rate < 0.006 s-1), suggesting that extremely slow rejection could sequester Cas9-RNA, increasing the Cas9 expression level necessary for genome editing thereby aggravating off-target effects. We also observed at least two different bound FRET states that may represent distinct steps in target search and proofreading.

scholarly journals DNA-sequence dependent positioning of the linker histone in a chromatosome: a single-pair FRET study

2020 ◽  
Author(s):  
Madhura De ◽  
Mehmet Ali Oeztuerk ◽  
Katalin Toth ◽  
Rebecca C. Wade
Keyword(s):  
Dna Sequence ◽  
Single Molecule ◽  
Binding Mode ◽  
Linker Histone ◽  
Single Pair ◽  
Globular Domain ◽  
Binding Modes ◽  
Single Molecule Fret ◽  
Fret Efficiency ◽  
Order Structures

The linker histone (LH) associates with the nucleosome with its globular domain (gH) binding in an on or off-dyad binding mode. The positioning of the LH may play a role in the compaction of higher-order structures of chromatin. Preference for different binding modes has been attributed to the LHs amino acid sequence. We here study the effect of the linker DNA (L-DNA) sequence on the positioning of a full-length LH, Xenopus laevis H1.0b, by employing single-molecule FRET spectroscopy. Chromatosomes were fluorescently labelled on one of the two 40bp long L-DNA arms, and on the gH. We varied 11bp of DNA flanking the core (non-palindromic Widom 601) of each chromatosome construct, making them either A-tract, purely GC, or mixed, with 64% AT. The gH consistently exhibited higher FRET efficiency with the L-DNA containing the A-tract, than that with the pure-GC stretch, even when the stretches were swapped. However, it did not exhibit higher FRET efficiency with the L-DNA containing 64% AT-rich mixed DNA, compared to the pure-GC stretch. We explain our observations with a FRET-distance restrained model that shows that the gH binds on-dyad and that two arginines mediate recognition of the A-tract via its characteristically narrow minor groove.

scholarly journals The post-PAM interaction of RNA-guided spCas9 with DNA dictates its target binding and dissociation

2019 ◽  
Vol 5 (11) ◽  
pp. eaaw9807 ◽  
Author(s):  
Qian Zhang ◽  
Fengcai Wen ◽  
Siqi Zhang ◽  
Jiachuan Jin ◽  
Lulu Bi ◽  
...  
Keyword(s):  
Dna Sequence ◽  
Single Molecule ◽  
Dna Interactions ◽  
Base Pairs ◽  
Complementary Dna ◽  
Interaction Site ◽  
Protospacer Adjacent Motif ◽  
Dna Loss ◽  
Target Binding

Cas9 is an RNA-guided endonuclease that targets complementary DNA for cleavage and has been repurposed for many biological usages. Cas9 activities are governed by its direct interactions with DNA. However, information about this interplay and the mechanism involved in its direction of Cas9 activity remain obscure. Using a single-molecule approach, we probed Cas9/sgRNA/DNA interactions along the DNA sequence and found two stable interactions flanking the protospacer adjacent motif (PAM). Unexpectedly, one of them is located approximately 14 base pairs downstream of the PAM (post-PAM interaction), which is beyond the apparent footprint of Cas9 on DNA. Loss or occupation of this interaction site on DNA impairs Cas9 binding and cleavage. Consistently, a downstream helicase could readily displace DNA-bound Cas9 by disrupting this relatively weak post-PAM interaction. Our work identifies a critical interaction of Cas9 with DNA that dictates its binding and dissociation, which may suggest distinct strategies to modulate Cas9 activity.

scholarly journals Diploid chromosome-scale assembly of the Muscadinia rotundifolia genome supports chromosome fusion and disease resistance gene expansion during Vitis and Muscadinia divergence

2021 ◽  
Author(s):  
Noé Cochetel ◽  
Andrea Minio ◽  
Mélanie Massonnet ◽  
Amanda M Vondras ◽  
Rosa Figueroa-Balderas ◽  
...  
Keyword(s):  
Single Molecule ◽  
Interleukin 1 ◽  
Plasmopara Viticola ◽  
Cabernet Sauvignon ◽  
Disease Resistance Gene ◽  
Chromosome Fusion ◽  
Protein Coding ◽  
Downy Mildews ◽  
A Genome ◽  
Muscadinia Rotundifolia

Abstract Muscadinia rotundifolia, the muscadine grape, has been cultivated for centuries in the southeastern United States. M. rotundifolia is resistant to many of the pathogens that detrimentally affect Vitis vinifera, the grape species commonly used for winemaking. For this reason, M. rotundifolia is a valuable genetic resource for breeding. Single-molecule real-time reads were combined with optical maps to reconstruct the two haplotypes of each of the 20 M. rotundifolia cv. Trayshed chromosomes. The completeness and accuracy of the assembly were confirmed using a high-density linkage map of M. rotundifolia. Protein-coding genes were annotated using an integrated and comprehensive approach. This included using Full-length cDNA sequencing (Iso-Seq) to improve gene structure and hypothetical spliced variant predictions. Our data strongly support that Muscadinia chromosomes 7 and 20 are fused in Vitis and pinpoint the location of the fusion in Cabernet Sauvignon and PN40024 chromosome 7. Disease-related gene numbers in Trayshed and Cabernet Sauvignon were similar, but their clustering locations were different. A dramatic expansion of the Toll/Interleukin-1 Receptor-like Nucleotide-Binding Site Leucine-Rich Repeat (TIR-NBS-LRR) class was detected on Trayshed chromosome 12 at the Resistance to Uncinula necator 1 (RUN1)/ Resistance to Plasmopara viticola 1 (RPV1) locus, which confers strong dominant resistance to powdery and downy mildews. A genome browser for Trayshed, its annotation, and an associated Blast tool are available at .www.grapegenomics.com

scholarly journals A machine learning approach for accurate and real-time DNA sequence identification

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yiren Wang ◽  
Mashari Alangari ◽  
Joshua Hihath ◽  
Arindam K. Das ◽  
M. P. Anantram
Keyword(s):  
Real Time ◽  
Dna Sequence ◽  
Single Molecule ◽  
Identification Accuracy ◽  
Measuring System ◽  
Identification System ◽  
Genetic Sequencing ◽  
Sequence Identification ◽  
Tree Classifier ◽  
Single Mismatch

Abstract Background The all-electronic Single Molecule Break Junction (SMBJ) method is an emerging alternative to traditional polymerase chain reaction (PCR) techniques for genetic sequencing and identification. Existing work indicates that the current spectra recorded from SMBJ experimentations contain unique signatures to identify known sequences from a dataset. However, the spectra are typically extremely noisy due to the stochastic and complex interactions between the substrate, sample, environment, and the measuring system, necessitating hundreds or thousands of experimentations to obtain reliable and accurate results. Results This article presents a DNA sequence identification system based on the current spectra of ten short strand sequences, including a pair that differs by a single mismatch. By employing a gradient boosted tree classifier model trained on conductance histograms, we demonstrate that extremely high accuracy, ranging from approximately 96 % for molecules differing by a single mismatch to 99.5 % otherwise, is possible. Further, such accuracy metrics are achievable in near real-time with just twenty or thirty SMBJ measurements instead of hundreds or thousands. We also demonstrate that a tandem classifier architecture, where the first stage is a multiclass classifier and the second stage is a binary classifier, can be employed to boost the single mismatched pair’s identification accuracy to 99.5 %. Conclusions A monolithic classifier, or more generally, a multistage classifier with model specific parameters that depend on experimental current spectra can be used to successfully identify DNA strands.

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