Centrosomes organize microtubules for mitotic spindle assembly and positioning. Forces mediated by these microtubules create tensile stresses on pericentriolar material (PCM), the outermost layer of centrosomes. How PCM resists these stresses is unclear at the molecular level. Here, we use cross-linking mass spectrometry (XL-MS) to map interactions underlying multimerization of SPD-5, an essential PCM scaffold component in . We identified an interaction hotspot in an alpha helical hairpin motif in SPD-5 (a.a. 541-677). XL-MS data, structural predictions, and mass photometry suggest that this region dimerizes to form a tetrameric coiled-coil. Mutating a helical section (a.a. 610-640) or a single residue (R592) inhibited PCM assembly in embryos. This phenotype was rescued by eliminating microtubule pulling forces, revealing that PCM assembly and material strength are interrelated. We propose that interactions mediated by the helical hairpin strongly bond SPD-5 molecules to each other, thus enabling PCM to assemble fully and withstand stresses generated by microtubules.
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http://dx.doi.org/10.1101/2023.05.16.540868 | DOI Listing |
Acta Histochem
January 2025
School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
In recent years, a great interest has been focused on the prebiotic origin of nucleic acids and life on Earth. An attractive idea is that life was initially based on an autocatalytic and autoreplicative RNA (the RNA-world). RNA duplexes are right-handed helical chains with antiparallel orientation, but the rationale for these features is not yet known.
View Article and Find Full Text PDFVet Immunol Immunopathol
January 2025
ICAR-National Bureau of Animal Genetic Resources, Karnal, India.
Cathelicidins are a diverse family of antimicrobial peptides found across many vertebrate species, playing a pivotal role in the innate immune system. These peptides exhibit a variety of structural motifs, including α-helices, β-hairpins, and random coils, contributing to their broad-spectrum antimicrobial activity. The structural diversity of cathelicidins allows them to interact with a wide range of microbial targets, thereby enhancing their antimicrobial efficacy.
View Article and Find Full Text PDFJ Mol Recognit
December 2024
Department of Gynecology, Affiliated Changzhou Second People's Hospital of Nanjing Medical University, Changzhou, China.
Transcriptional enhanced associate domain (Tead)-mediated Hippo signaling pathway regulates diverse physiological processes; its dysfunction has been implicated in an increasing number of human gynecological cancers. The transcriptional coactivator with PDZ-binding motif (Taz) binds to and then activates Tead through forming a three-helix bundle (THB) at their complex interface. The THB is defined by a double-helical hairpin from Tead and a single α-helix from Taz, serving as the key interaction hotspot between Tead and Taz.
View Article and Find Full Text PDFbioRxiv
November 2024
Department of Chemistry University of Massachusetts, Amherst, MA 01003, USA.
RNAs are major drivers of phase separation in the formation of biomolecular condensates. Recent studies suggest that RNAs can also undergo protein-free phase separation in the presence of divalent ions or crowding agents. Much remains to be understood regarding how the complex interplay of base stacking, base pairing, electrostatics, ion interactions, and structural propensities governs the phase behaviour of RNAs.
View Article and Find Full Text PDFProtein Sci
December 2024
i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
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