Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As superfamily 2 (SF2)-type translocases, chromatin remodelers are expected to use an inchworm-type mechanism to walk along DNA. Yet how they move DNA around the histone core has not been clear. Here we show that a remodeler ATPase motor can shift large segments of DNA by changing the twist and length of nucleosomal DNA at superhelix location 2 (SHL2). Using canonical and variant 601 nucleosomes, we find that the Saccharomyces cerevisiae Chd1 remodeler decreased DNA twist at SHL2 in nucleotide-free and ADP-bound states, and increased twist with transition state analogs. These differences in DNA twist allow the open state of the ATPase to pull in ~1 base pair (bp) by stabilizing a small DNA bulge, and closure of the ATPase to shift the DNA bulge toward the dyad. We propose that such formation and elimination of twist defects underlie the mechanism of nucleosome sliding by CHD-, ISWI-, and SWI/SNF-type remodelers.
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PMID:A twist defect mechanism for ATP-dependent translocation of nucleosomal DNA. 2980 47

All ATP-dependent chromatin remodelers have a DNA translocase domain that moves along double-stranded DNA when hydrolyzing ATP, which is the key action leading to DNA moving through nucleosomes. Recent structural and biochemical data from a variety of different chromatin remodelers have revealed that there are three basic ways in which these remodelers self-regulate their chromatin remodeling activity. In several instances, different domains within the catalytic subunit or accessory subunits through direct protein-protein interactions can modulate the ATPase and DNA translocation properties of the DNA translocase domain. These domains or subunits can stabilize conformations that either promote or interfere with the ability of the translocase domain to bind or retain DNA during translocation or alter the ability of the enzyme to hydrolyze ATP. Second, other domains or subunits are often necessary to anchor the remodeler to nucleosomes to couple DNA translocation and ATP hydrolysis to DNA movement around the histone octamer. These anchors provide a fixed point by which remodelers can generate sufficient torque to disrupt histone-DNA interactions and mobilize nucleosomes. The third type of self-regulation is in those chromatin remodelers that space nucleosomes or stop moving nucleosomes when a particular length of linker DNA has been reached. We refer to this third class as DNA sensors that can allosterically regulate nucleosome mobilization. In this review, we will show examples of these from primarily the INO80/SWR1, SWI/SNF and ISWI/CHD families of remodelers.
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PMID:Regulation of ATP-dependent chromatin remodelers: accelerators/brakes, anchors and sensors. 3046 22

Chromatin remodelling complexes evict, slide, insert or replace nucleosomes, which represent an intrinsic barrier for access to DNA. These remodellers function in most aspects of genome utilization including transcription-factor binding, DNA replication and repair^1,2. Although they are frequently mutated in cancer³, it remains largely unclear how the four mammalian remodeller families (SWI/SNF, ISWI, CHD and INO80) orchestrate the global organization of nucleosomes. Here we generated viable embryonic stem cells that lack SNF2H, the ATPase of ISWI complexes, enabling study of SNF2H cellular function, and contrast it to BRG1, the ATPase of SWI/SNF. Loss of SNF2H decreases nucleosomal phasing and increases linker lengths, providing in vivo evidence for an ISWI function in ruling nucleosomal spacing in mammals. Systematic analysis of transcription-factor binding reveals that these remodelling activities have specific effects on binding of different transcription factors. One group critically depends on BRG1 and contains the transcriptional repressor REST, whereas a non-overlapping set of transcription factors, including the insulator protein CTCF, relies on SNF2H. This selectivity readily explains why chromosomal folding and insulation of topologically associated domains requires SNF2H, but not BRG1. Collectively, this study shows that mammalian ISWI is critical for nucleosomal periodicity and nuclear organization and that transcription factors rely on specific remodelling pathways for correct genomic binding.
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PMID:Mammalian ISWI and SWI/SNF selectively mediate binding of distinct transcription factors. 3099 47

The eukaryotic genetic material is packaged in the form of chromatin by wrapping DNA around nucleosomes. Cells maintain chromatin in a dynamic state by utilising various ATP-dependent chromatin remodelling complexes which can induce structural transformations in the chromatin. All chromatin remodelers contain an ATP hydrolysing-DNA translocase motor which facilitates nucleosomal DNA translocation. By DNA translocation ISWI and CHD subfamily remodelers slide nucleosomes and arrange them in a regularly spaced array. While SWI/SNF subfamily remodelers evict or displace nucleosomes from chromatin, which promotes recruitment of transcription machinery and DNA repair factors on the DNA. Besides DNA translocation, ISWI, CHD and INO80 subfamily remodelers escort nucleosome organisation and editing. In this review; we discuss different mechanisms by which chromatin remodelers regulate chromatin accessibility, nucleosome assembly and nucleosome editing. We attempt to elucidate how their action mediates various cellular and developmental processes, and their deregulation leads to disease pathogenesis. We emphasised on their role in cancer progression and potential therapeutic implications of these complexes. We also described the drugs and strategies which are being developed to target different subunits of remodelling complexes, histone modifying enzymes and polycomb repressive complex. This includes ATPase inhibitors, EZH2 (enhancer of zeste homolog 2) inhibitors, BET (bromodomain and extra terminal) inhibitors, PROTAC (proteolysis targeting chimaera) and inhibitors of protein-protein interaction.
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PMID:The mechanisms of action of chromatin remodelers and implications in development and disease. 3280 11


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