Biology subjects

Batters, C.

Publications and source records attributed to Batters, C..

6 recordsLinked to original sources

bioRxiv2026

Mechanism and regulation of Bim1 interactions withthe S. cerevisiae outer kinetochore Ndc80 complex

During eukaryotic cell division, kinetochores couple duplicated sister chromatids to mitotic spindle microtubules to mediate faithful chromosome segregation. Although the main kinetochore attachment sites to centromeric chromatin and microtubules are known, additional factors including microtubule-associated proteins are required for efficient chromosome biorientation and segregation in vivo. However, the roles and mechanisms of these factors in kinetochore function remain to be fully understood. Here, we characterise a previously unrecognised interaction between the microtubule plus-end tracking protein Bim1 and the outer kinetochore Ndc80 complex (Ndc80c) in S. cerevisiae. We show this interaction is mediated by a conserved SxIP motif within the intrinsically disordered Ndc80 N-terminus (Ndc80N), augmented by a secondary binding site containing an alpha-helical segment. This Ndc80 interaction with Bim1 increases the strength of Ndc80c-microtubule attachments. Phosphorylation of the Bim1-binding region of Ndc80N by the error correction Ipl1/Aurora B protein kinase alters its secondary structure and weakens the Bim1-Ndc80c interaction, providing a potential additional regulatory mechanism for how incorrect kinetochore-microtubule attachments are destabilised during error correction.

molecular biology↗

bioRxiv2026

Mechanism and regulation of the Bim1 interaction withthe outer kinetochore Ndc80 complex in S. cerevisiae

During eukaryotic cell division, kinetochores couple duplicated sister chromatids to mitotic spindle microtubules to mediate faithful chromosome segregation. Although the main kinetochore attachment sites to centromeric chromatin and microtubules are known, additional factors including microtubule-associated proteins are required for efficient chromosome biorientation and segregation in vivo. However, the roles and mechanisms of these factors in kinetochore function remain to be fully understood. Here, we characterise a previously unrecognised interaction between the microtubule plus-end tracking protein Bim1 and the outer kinetochore Ndc80 complex (Ndc80c) in S. cerevisiae. We show this interaction is mediated by a conserved SxIP motif within the intrinsically disordered Ndc80 N-terminus (Ndc80N), augmented by a secondary binding site containing an -helical segment. This Ndc80 interaction with Bim1 increases the strength of Ndc80c-microtubule attachments. Phosphorylation of the Bim1-binding region of Ndc80N by the error correction Ipl1/Aurora B protein kinase alters its secondary structure and weakens the Bim1-Ndc80c interaction, providing a potential additional regulatory mechanism for how incorrect kinetochore-microtubule attachments are destabilised during error correction.

cell biology↗

bioRxiv2025

Plasmodium falciparum Myosin F with a Rab-like tail domain localises to perinuclear membranes and associates with trafficking proteins

Members of the myosin superfamily are found in all eukaryotes, including Plasmodium falciparum, the parasite that causes malaria. Plasmodium falciparum expresses six myosins, but apart from PfMyoA, these motors remain largely uncharacterised. This includes the class XXII myosin PfMyoF. Here, we characterise PfMyoF using structural prediction tools, biochemical assays, and advanced imaging. We show that PfMyoF is a plus-end directed, processive motor with a long neck domain containing six IQ motifs that bind the calmodulin homologue PfCaM. PfMyoF can dimerise and is predicted to adopt an autoinhibited conformation via tail backfolding. The PfMyoF tail contains a Rab-like domain that has not been identified in any other known class of myosin. Pull-down experiments show interactions between endogenous PfMyoF and trafficking proteins, including the vesicle marker PfRab18. Expansion and immunoelectron microscopy reveal that PfMyoF localises to a perinuclear membrane compartment. Our findings define PfMyoF as the first known myosin with a Rab-like domain and highlight its potential role in parasite membrane trafficking pathways.

molecular biology↗

bioRxiv2025

Structure of a transcribing Pol II-DSIF-SPT6-U1 snRNP complex

RNA polymerase II (Pol II) facilitates co-transcriptional splicing by recruiting the U1 small nuclear ribonucleoprotein particle (U1 snRNP) to the nascent transcripts. Here, we report the cryo-electron microscopy structure of a transcribing Pol II-U1 snRNP complex with elongation factors DSIF and SPT6. Furthermore, our biochemical analysis revealed that the phosphorylated Pol II carboxyl-terminal domain and SPT6 interact directly with U1 snRNP proteins, facilitating its recruitment to the elongation complex. This multivalent interaction allows efficient spliceosome assembly and ensures transcription processivity.

molecular biology↗

bioRxiv2024

The actomyosin system is essential for the integrity of the endosomal system in bloodstream form Trypanosoma brucei

The actin cytoskeleton is a ubiquitous feature of eukaryotic cells, yet its complexity varies across different taxa. In the parasitic protist Trypanosoma brucei, a rudimentary actomyosin system consisting of one actin gene and two myosin genes has been retained despite significant investment in the microtubule cytoskeleton. The functions of this highly simplified actomyosin system remain unclear, but appear to centre on the endomembrane system. Here, advanced light and electron microscopy imaging techniques together with biochemical and biophysical assays were used to explore the relationship between the actomyosin and endomembrane systems. The class I myosin (TbMyo1) had a large cytosolic pool and its ability to translocate actin filaments in vitro was shown here for the first time. TbMyo1 exhibited strong association with the endosomal system and was additionally found on glycosomes. At the endosomal membranes, TbMyo1 colocalised with markers for early and late endosomes (TbRab5A and TbRab7, respectively), but not with the marker associated with recycling endosomes (TbRab11). Actin and myosin were simultaneously visualised for the first time in trypanosomes using an anti-actin chromobody. Disruption of the actomyosin system using the actin-depolymerising drug latrunculin A resulted in a delocalisation of both the actin chromobody signal and an endosomal marker, and was accompanied by a specific loss of endosomal structure. This suggests that the actomyosin system is required for maintaining endosomal integrity in T. brucei.

cell biology↗

bioRxiv2023

Mechanism of outer kinetochore assembly on microtubules and its regulation by mitotic error correction

Kinetochores couple chromosomes to the mitotic spindle and transduce the energy of microtubule depolymerization to segregate the genome during cell division. Kinetochore - microtubule attachments are often initially erroneous and subject to a mitotic error correction (EC) mechanism that drives their turnover until biorientation is achieved. How this is accomplished and regulated, and how kinetochore-mediated chromosome segregation occurs at a molecular level remain major outstanding questions. Here we describe the cryo-electron microscopy (cryo-EM) structure of the budding yeast outer kinetochore Ndc80 and Dam1 ring complexes assembled onto microtubules. We observe coordinated interactions of the outer kinetochore complexes through multiple interfaces, in addition to a short staple within the Dam1 subunit that facilitates Dam1c ring assembly. Perturbation of these interfaces results in loss of yeast viability. Force-rupture assays indicated this is a consequence of substantial reductions in kinetochore - microtubule binding strength. EC-mediated phosphorylation of Ndc80c-Dam1c interfaces would drive complex disassembly, whereas Dam1 staple phosphorylation would promote Dam1c ring disassembly, explaining how kinetochore - microtubule attachments are destabilized and reset by the EC mechanism. One-Sentence SummaryPhosphorylation disrupts the outer kinetochore to regulate kinetochore-microtubule attachments in mitotic error correction.

molecular biology↗