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

The actin cytoskeleton is a ubiquitous feature of eukaryotic cells, yet its complexity varies across different taxa. In the parasitic protist , 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.

Characterisation of TbSmee1 suggests endocytosis allows surface-bound cargo to enter the trypanosome flagellar pocket.

All endocytosis and exocytosis in the African trypanosome Trypanosoma brucei occurs at a single subdomain of the plasma membrane. This subdomain, the flagellar pocket, is a small vase-shaped invagination containing the root of the single flagellum of the cell. Several cytoskeleton-associated multiprotein complexes are coiled around the neck of the flagellar pocket on its cytoplasmic face.

Response to comment on 'Unexpected plasticity in the life cycle of '.

We thank Keith Matthews and Stephen Larcombe for their thoughtful comment, which follows the good tradition of public scientific discourse (Matthews and Larcombe, 2022). While their remarks have prompted us to take another critical look at our data, we think that they neither alter our conclusions nor offer a practical alternative explanation. In essence, we see two possible interpretations of our experiments: either the trypanosome life cycle can accommodate a more flexible role for the slender stage, or the definition of the stumpy stage needs to be radically changed.

Bhalin, an Essential Cytoskeleton-Associated Protein of Linking BILBO1 of the Flagellar Pocket Collar with the Hook Complex.

Background: In most trypanosomes, endo and exocytosis only occur at a unique organelle called the flagellar pocket (FP) and the flagellum exits the cell via the FP. Investigations of essential cytoskeleton-associated structures located at this site have revealed a number of essential proteins. The protein BILBO1 is located at the neck of the FP in a structure called the flagellar pocket collar (FPC) and is essential for biogenesis of the FPC and parasite survival.

Unexpected plasticity in the life cycle of .

African trypanosomes cause sleeping sickness in humans and nagana in cattle. These unicellular parasites are transmitted by the bloodsucking tsetse fly. In the mammalian host's circulation, proliferating slender stage cells differentiate into cell cycle-arrested stumpy stage cells when they reach high population densities.

Structures of three MORN repeat proteins and a re-evaluation of the proposed lipid-binding properties of MORN repeats.

MORN (Membrane Occupation and Recognition Nexus) repeat proteins have a wide taxonomic distribution, being found in both prokaryotes and eukaryotes. Despite this ubiquity, they remain poorly characterised at both a structural and a functional level compared to other common repeats. In functional terms, they are often assumed to be lipid-binding modules that mediate membrane targeting.

Hidden value.

The fact that it is difficult to evaluate and compare the outputs of individual researchers might actually be good for science.

The rat race.

Labmates are colleagues, friends, comforters…and competitors.

A Bosman ruling for science.

The introduction of transfer fees could revolutionise the scientific job market. [Image: see text]

Resurrection science.

Digging up the graves of old ideas can be a fertile source of inspiration. [Image: see text]

Nobody at the top.

Science bears some hallmarks of religion. But, unlike many organized religions, there is no central authority and no tenet remains unchallenged. [Image: see text]

Let's get fISSical: fast in silico synchronization as a new tool for cell division cycle analysis.

Cell cycle progression is a question of fundamental biological interest. The coordinated duplication and segregation of all cellular structures and organelles is however an extremely complex process, and one which remains only partially understood even in the most intensively researched model organisms. Trypanosomes are in an unusual position in this respect - they are both outstanding model systems for fundamental questions in eukaryotic cell biology, and pathogens that are the causative agents of three of the neglected tropical diseases.

Two flagellar BAR domain proteins in Trypanosoma brucei with stage-specific regulation.

Trypanosomes are masters of adaptation to different host environments during their complex life cycle. Large-scale proteomic approaches provide information on changes at the cellular level, and in a systematic way. However, detailed work on single components is necessary to understand the adaptation mechanisms on a molecular level.

Assembly mechanism of Trypanosoma brucei BILBO1 at the flagellar pocket collar.

The flagellar pocket is a bulb-like invagination of the plasma membrane that encloses the base of the single flagellum in trypanosomes. It is the site of all endo- and exocytic activity in the parasite and has thus been proposed to be a therapeutic target. At the neck of the flagellar pocket is an electron-dense cytoskeletal structure named the flagellar pocket collar.

Form, Fabric, and Function of a Flagellum-Associated Cytoskeletal Structure.

Trypanosoma brucei is a uniflagellated protist and the causative agent of African trypanosomiasis, a neglected tropical disease. The single flagellum of T. brucei is essential to a number of cellular processes such as motility, and has been a longstanding focus of scientific enquiry.

A MORN Repeat Protein Facilitates Protein Entry into the Flagellar Pocket of Trypanosoma brucei.

The parasite Trypanosoma brucei lives in the bloodstream of infected mammalian hosts, fully exposed to the adaptive immune system. It relies on a very high rate of endocytosis to clear bound antibodies from its cell surface. All endo- and exocytosis occurs at a single site on its plasma membrane, an intracellular invagination termed the flagellar pocket.

Assembly mechanism of Trypanosoma brucei BILBO1, a multidomain cytoskeletal protein.

Trypanosoma brucei BILBO1 (TbBILBO1) is an essential component of the flagellar pocket collar of trypanosomes. We recently reported the high resolution structure of the N-terminal domain of TbBILBO1. Here, we provide further structural dissections of its other three constituent domains: EF-hand, coiled coil, and leucine zipper.

Structure of the TbBILBO1 protein N-terminal domain from Trypanosoma brucei reveals an essential requirement for a conserved surface patch.

TbBILBO1 is the only known component of the flagellar pocket collar, a cytoskeletal barrier element found in trypanosomes. The N-terminal domain (NTD) of TbBILBO1 was found to be dispensable for targeting of the protein in vivo. However, overexpression of constructs lacking the NTD caused complete growth inhibition, implying an essential requirement for this domain.

Novel bilobe components in Trypanosoma brucei identified using proximity-dependent biotinylation.

The trypanosomes are a family of parasitic protists of which the African trypanosome, Trypanosoma brucei, is the best characterized. The complex and highly ordered cytoskeleton of T. brucei has been shown to play vital roles in its biology but remains difficult to study, in large part owing to the intractability of its constituent proteins.

Morphology of the trypanosome bilobe, a novel cytoskeletal structure.

The trypanosome bilobe is a cytoskeletal structure of unclear function. To date, four proteins have been shown to localize stably to it: TbMORN1, TbLRRP1, TbCentrin2, and TbCentrin4. In this study, a combination of immunofluorescence microscopy and electron microscopy was used to explore the morphology of the bilobe and its relationship to other nearby cytoskeletal structures in the African trypanosome procyclic trypomastigote.

The bilobe structure of Trypanosoma brucei contains a MORN-repeat protein.

The Golgi of the kinetoplastid parasite Trypanosoma brucei is closely apposed to a bilobe structure containing TbCentrin2 and TbCentrin4 in procyclic cells. However, both are additionally localized to the basal bodies. Here we report the characterization of a membrane occupation and recognition nexus (MORN)-repeat protein, TbMORN1, present at the bilobe but not at the basal body.

T6BP and NDP52 are myosin VI binding partners with potential roles in cytokine signalling and cell adhesion.

Myosin VI has been implicated in many cellular processes including endocytosis, secretion, membrane ruffling and cell motility. We carried out a yeast two-hybrid screen and identified TRAF6-binding protein (T6BP) and nuclear dot protein 52 (NDP52) as myosin VI binding partners. Myosin VI interaction with T6BP and NDP52 was confirmed in vitro and in vivo and the binding sites on each protein were accurately mapped.

Analysis of methylated and unmethylated polygalacturonic acid structure by polysaccharide analysis using carbohydrate gel electrophoresis.

The electrophoretic migration in polyacrylamide gels of oligogalacturonic acids (OGAs) derivatized by a fluorophore (2-aminoacridone) was studied. We found conditions such that OGAs can be separated up to a degree of polymerization (DP) of 40. The migration was dependent on degree of methylation and DP, because the OGA mobility relies on the charge of the galacturonic acid residues.