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Walker DR, Jara KA, Rolland AD, Brooks C, Hare W, Swansiger AK, Reardon PN, Prell JS, Barbar EJ. Linker Length Drives Heterogeneity of Multivalent Complexes of Hub Protein LC8 and Transcription Factor ASCIZ. Biomolecules 2023; 13:404. [PMID: 36979339 PMCID: PMC10046861 DOI: 10.3390/biom13030404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/08/2023] [Accepted: 02/18/2023] [Indexed: 02/24/2023] Open
Abstract
LC8, a ubiquitous and highly conserved hub protein, binds over 100 proteins involved in numerous cellular functions, including cell death, signaling, tumor suppression, and viral infection. LC8 binds intrinsically disordered proteins (IDPs), and although several of these contain multiple LC8 binding motifs, the effects of multivalency on complex formation are unclear. Drosophila ASCIZ has seven motifs that vary in sequence and inter-motif linker lengths, especially within subdomain QT2-4 containing the second, third, and fourth LC8 motifs. Using isothermal-titration calorimetry, analytical-ultracentrifugation, and native mass-spectrometry of QT2-4 variants, with methodically deactivated motifs, we show that inter-motif spacing and specific motif sequences combine to control binding affinity and compositional heterogeneity of multivalent duplexes. A short linker separating strong and weak motifs results in stable duplexes but forms off-register structures at high LC8 concentrations. Contrastingly, long linkers engender lower cooperativity and heterogeneous complexation at low LC8 concentrations. Accordingly, two-mers, rather than the expected three-mers, dominate negative-stain electron-microscopy images of QT2-4. Comparing variants containing weak-strong and strong-strong motif combinations demonstrates sequence also regulates IDP/LC8 assembly. The observed trends persist for trivalent ASCIZ subdomains: QT2-4, with long and short linkers, forms heterogeneous complexes, whereas QT4-6, with similar mid-length linkers, forms homogeneous complexes. Implications of linker length variations for function are discussed.
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Affiliation(s)
- Douglas R. Walker
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Kayla A. Jara
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Amber D. Rolland
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403, USA
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Coban Brooks
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Wendy Hare
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Andrew K. Swansiger
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403, USA
| | - Patrick N. Reardon
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
- NMR Facility, Oregon State University, Corvallis, OR 97331, USA
| | - James S. Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403, USA
- Materials Science Institute, University of Oregon, Eugene, OR 97403, USA
| | - Elisar J. Barbar
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
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Jara KA, Loening NM, Reardon PN, Yu Z, Woonnimani P, Brooks C, Vesely CH, Barbar EJ. Multivalency, autoinhibition, and protein disorder in the regulation of interactions of dynein intermediate chain with dynactin and the nuclear distribution protein. eLife 2022; 11:80217. [PMID: 36416224 PMCID: PMC9771362 DOI: 10.7554/elife.80217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
As the only major retrograde transporter along microtubules, cytoplasmic dynein plays crucial roles in the intracellular transport of organelles and other cargoes. Central to the function of this motor protein complex is dynein intermediate chain (IC), which binds the three dimeric dynein light chains at multivalent sites, and dynactin p150Glued and nuclear distribution protein (NudE) at overlapping sites of its intrinsically disordered N-terminal domain. The disorder in IC has hindered cryo-electron microscopy and X-ray crystallography studies of its structure and interactions. Here we use a suite of biophysical methods to reveal how multivalent binding of the three light chains regulates IC interactions with p150Glued and NudE. Using IC from Chaetomium thermophilum, a tractable species to interrogate IC interactions, we identify a significant reduction in binding affinity of IC to p150Glued and a loss of binding to NudE for constructs containing the entire N-terminal domain as well as for full-length constructs when compared to the tight binding observed with short IC constructs. We attribute this difference to autoinhibition caused by long-range intramolecular interactions between the N-terminal single α-helix of IC, the common site for p150Glued, and NudE binding, and residues closer to the end of the N-terminal domain. Reconstitution of IC subcomplexes demonstrates that autoinhibition is differentially regulated by light chains binding, underscoring their importance both in assembly and organization of IC, and in selection between multiple binding partners at the same site.
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Affiliation(s)
- Kayla A Jara
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | | | - Patrick N Reardon
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States,Oregon State University NMR FacilityCorvallisUnited States
| | - Zhen Yu
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | - Prajna Woonnimani
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | - Coban Brooks
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | - Cat H Vesely
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | - Elisar J Barbar
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
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Eastwood EL, Jara KA, Bornelöv S, Munafò M, Frantzis V, Kneuss E, Barbar EJ, Czech B, Hannon GJ. Dimerisation of the PICTS complex via LC8/Cut-up drives co-transcriptional transposon silencing in Drosophila. eLife 2021; 10:e65557. [PMID: 33538693 PMCID: PMC7861614 DOI: 10.7554/elife.65557] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/04/2021] [Indexed: 12/16/2022] Open
Abstract
In animal gonads, the PIWI-interacting RNA (piRNA) pathway guards genome integrity in part through the co-transcriptional gene silencing of transposon insertions. In Drosophila ovaries, piRNA-loaded Piwi detects nascent transposon transcripts and instructs heterochromatin formation through the Panoramix-induced co-transcriptional silencing (PICTS) complex, containing Panoramix, Nxf2 and Nxt1. Here, we report that the highly conserved dynein light chain LC8/Cut-up (Ctp) is an essential component of the PICTS complex. Loss of Ctp results in transposon de-repression and a reduction in repressive chromatin marks specifically at transposon loci. In turn, Ctp can enforce transcriptional silencing when artificially recruited to RNA and DNA reporters. We show that Ctp drives dimerisation of the PICTS complex through its interaction with conserved motifs within Panoramix. Artificial dimerisation of Panoramix bypasses the necessity for its interaction with Ctp, demonstrating that conscription of a protein from a ubiquitous cellular machinery has fulfilled a fundamental requirement for a transposon silencing complex.
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Affiliation(s)
- Evelyn L Eastwood
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Kayla A Jara
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | - Susanne Bornelöv
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Marzia Munafò
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Vasileios Frantzis
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Emma Kneuss
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Elisar J Barbar
- Department of Biochemistry and Biophysics, Oregon State UniversityCorvallisUnited States
| | - Benjamin Czech
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Gregory J Hannon
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
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Jara KA, Loening NM, Barbar EJ. Role of Disorder in the Regulation of Dynein's Intermediate Chain. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Reardon PN, Jara KA, Rolland AD, Smith DA, Hoang HTM, Prell JS, Barbar EJ. The dynein light chain 8 (LC8) binds predominantly "in-register" to a multivalent intrinsically disordered partner. J Biol Chem 2020; 295:4912-4922. [PMID: 32139510 PMCID: PMC7152752 DOI: 10.1074/jbc.ra119.011653] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 03/03/2020] [Indexed: 01/18/2023] Open
Abstract
Dynein light chain 8 (LC8) interacts with intrinsically disordered proteins (IDPs) and influences a wide range of biological processes. It is becoming apparent that among the numerous IDPs that interact with LC8, many contain multiple LC8-binding sites. Although it is established that LC8 forms parallel IDP duplexes with some partners, such as nucleoporin Nup159 and dynein intermediate chain, the molecular details of these interactions and LC8's interactions with other diverse partners remain largely uncharacterized. LC8 dimers could bind in either a paired "in-register" or a heterogeneous off-register manner to any of the available sites on a multivalent partner. Here, using NMR chemical shift perturbation, analytical ultracentrifugation, and native electrospray ionization MS, we show that LC8 forms a predominantly in-register complex when bound to an IDP domain of the multivalent regulatory protein ASCIZ. Using saturation transfer difference NMR, we demonstrate that at substoichiometric LC8 concentrations, the IDP domain preferentially binds to one of the three LC8 recognition motifs. Further, the differential dynamic behavior for the three sites and the size of the fully bound complex confirmed an in-register complex. Dynamics measurements also revealed that coupling between sites depends on the linker length separating these sites. These results identify linker length and motif specificity as drivers of in-register binding in the multivalent LC8-IDP complex assembly and the degree of compositional and conformational heterogeneity as a promising emerging mechanism for tuning of binding and regulation.
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Affiliation(s)
- Patrick N Reardon
- Oregon State University NMR Facility, Oregon State University, Corvallis, Oregon 97331
| | - Kayla A Jara
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
| | - Amber D Rolland
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Delaney A Smith
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
| | - Hanh T M Hoang
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Materials Science Institute, University of Oregon, Eugene, Oregon 97403
| | - Elisar J Barbar
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
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