N-terminal Domain of TDP43 Enhances Liquid-Liquid Phase Separation of Globular Proteins

Liquid-liquid phase separation (LLPS) of proteins is involved in a growing number of cellular processes. Most proteins with LLPS harbor intrinsically disordered regions (IDR), which serve as a guideline to search for cellular proteins that potentially phase separate. Herein, we reveal that oligomerization lowers the barriers for LLPS and could act as a general mechanism to enhance LLPS of proteins domains independent of IDR. Using TDP43 as a model system, we found that deleting its IDR resulted in LLPS that was dependent on the oligomerization of the N-terminal domain (NTD). Replacing TDP43′s NTD with other oligomerization domains enhanced the LLPS proportionately to the state of oligomerization. In addition to TDP43, fusing NTD to other globular proteins without known LLPS behavior also drove their phase separation in a manner dependent on oligomerization. Finally, we demonstrate that heterooligomers composed of NTD-fused proteins can be driven into droplets through NTD interactions. Our results potentiate a new paradigm for using oligomerization domains as a signature to systematically identify cellular proteins with LLPS behavior, thus broadening the scope of this exciting research field.     

A Propos D'observations Sur L'ultrastructure Du Cilié Cyrtolophosis Mucicola Stokes, 1885

RESUME L'étude détaillée du cortex et des organelles buccaux de Cyrtolophosis mucicola montre que ce Cilié possède une organisation structural corticale comparable à celle de Woodruffia, Platyophrya, Kuklikophrya et des Colpoda . Tout en restant conforme au plan général d'organisation de ces derniers, il a des variations spécifiques décelées au niveau des organelles buccaux qui confirment la position de C. mucicola dans la famille des Cyrtolophosididae , incluse dans le sous-ordre des PLATYOPHRYINA.     

Effect of vesicle traps on traffic jam formation in fast axonal transport

The purpose of this paper is to develop a model for simulation of the formation of organelle traps in fast axonal transport. Such traps may form in the regions of microtubule polar mismatching. Depending on the orientation of microtubules pointing toward the trap region, these traps can accumulate either plus-end or minus-end oriented vesicles. The model predicts that the maximum concentrations of organelles occur at the boundaries of the trap regions; the overall concentration of organelles in the axon with traps is greatly increased compared to that in a healthy axon, which is expected to contribute to mechanical damages of the axon. The organelle traps induce hindrance to organelle transport down the axon; the total organelle flux down the axon with traps is found to be significantly reduced compared to that in a healthy axon.     

The functions of kinesin and kinesin-related proteins in eukaryotes

ABSTRACT

Kinesins constitute a superfamily of ATP-driven microtubule motor enzymes that convert the chemical energy of ATP hydrolysis into mechanical work along microtubule tracks. Kinesins are found in all eukaryotic organisms and are essential to all eukaryotic cells, involved in diverse cellular functions such as microtubule dynamics and morphogenesis, chromosome segregation, spindle formation and elongation and transport of organelles. In this review, we explore recently reported functions of kinesins in eukaryotes and compare their specific cargoes in both plant and animal kingdoms to understand the possible roles of uncharacterized motors in a kingdom based on their reported functions in other kingdoms.     

Preparation of chloroplast DNA from pea plastids isolated in a medium of high ionic strength

A simple, rapid, and inexpensive method for the preparation and purification of chloroplast DNA (cpDNA) from pea has been developed. The crucial step is the isolation of chloroplasts in a medium of high ionic strength (I congruent equal to 1.40 M). CpDNA from pea prepared according to this method has successfully been used for restriction enzyme mapping, Southern transfers, and cloning.     

Hybrid pigment organelles in an invertebrate

Summary Observations of a number of vertebrate chromatophores have revealed the presence of more than one type of pigment organelles, suggesting that the different types are all derived from an equipotential organelle able to differentiate into any of the major pigment-containing organelles (Bagnara, 1972). Observations are presented concerning the occurrence of hybrid pigment inclusions, i.e., all kinds of intergrades between melanosomes, pterinosomes, and reflecting platelets in pigment cells of the daddy-long-legs. It therefore seems possible that pigment organelles in some invertebrates may also be derived from a common pluripotential primordial organelle.Supported from the Deutsche Forschungsgemeinschaft is gratefully acknowledged     

Direct Targeting of Proteins from the Cytosol to Organelles: The ER versus Endosymbiotic Organelles

In eukaryotic cells consisting of many different types of organelles, targeting of organellar proteins is one of the most fundamental cellular processes. Proteins belonging to the endoplasmic reticulum (ER), chloroplasts and mitochondria are targeted individually from the cytosol to their cognate organelles. As the targeting to these organelles occurs in the cytosol during or after translation, the most crucial aspect is how specific targeting to these three organelles can be achieved without interfering with other targeting pathways. For these organelles, multiple mechanisms are used for targeting proteins, but the exact mechanism used depends on the type of protein and organelle, the location of targeting signals in the protein and the location of the protein in the organelle. In this review, we discuss the various mechanisms involved in protein targeting to the ER, chloroplasts and mitochondria, and how the targeting specificity is determined for these organelles in plant cells .     

Bayesian Confidence Intervals for Multiplexed Proteomics Integrate Ion-statistics with Peptide Quantification Concordance,

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Highlights

• •Bayesian Beta-Binomial model integrates ion statistics with peptide ratio agreement.
• •Model appropriately interprets information from low signal peptides.
• •Confidence can be assigned even without replicates.
• •Model adds sensitivity to detection of small changes.

     

Unraveling Hidden Components of the Chloroplast Envelope Proteome: Opportunities and Limits of Better MS Sensitivity

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Highlights

• •Identification of previously undetected chloroplast envelope proteins.
• •Up to date manual annotation of genuine (or shared) envelope components.
• •New hypotheses for localizations, functions, interactions among cell compartments.
• •A new resource of significant value to the broader plant science community.

     

BioID Performed on Golgi Enriched Fractions Identify C10orf76 as a GBF1 Binding Protein Essential for Golgi Maintenance and Secretion

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Highlights

• •BioID with Golgi fractions identified C10orf76 as proximal to GBF1.
• •Tagged C10orf76 overlaps with Golgi markers.
• •C10orf76 binds GBF1 and exchanges rapidly between free and bound forms.
• •C10orf76 is essential for maintenance of the Golgi and for secretion.