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Extended synaptotagmins (E-Syts) are a family of lipid transfer proteins (LTPs) located at the endoplasmic reticulum (ER)-plasma membrane (PM) contact sites in eukaryotic cells. They possess a conserved synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain and two to five C2 domains. While the membrane tethering function of E-Syts has been well studied in diverse species, recent studies revealed that the mammalian E-Syt1 and its yeast homolog tricalbin 3 (Tcb3) could transport lipids between the opposed membrane. Mechanical studies suggested SYT1 transfers lipids fundamentally through the SMP domain, but the lipid transport requires the regulation of C2 domain-mediated membrane tethering. In addition, both E-Syt1 and Tcb3 are Ca

The GLUT4 vesicle fusion is mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and a variety of regulatory proteins. For example, synip and tomosyn negatively regulate GLUT4 SNARE-mediated membrane fusion. Here we describe in vitro reconstituted assays to determine the molecular mechanisms of SNAREs, synip, and tomosyn. These methods can also be extended to the studies of other types of membrane fusion events.

Intracellular vesicle fusion requires the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and their cognate Sec1/Munc18 (SM) proteins. How SM proteins act in concert with trans-SNARE complexes to promote membrane fusion remains incompletely understood. Munc18c, a broadly distributed SM protein, selectively regulates multiple exocytotic pathways, including GLUT4 exocytosis. Here, using an in vitro reconstituted system, we discovered a SNARE-like peptide (SLP), conserved in Munc18-1 of synaptic exocytosis, is crucial to the stimulatory activity of Munc18c in vesicle fusion. The direct stimulation of the SNARE-mediated fusion reaction by SLP further supported the essential role of this fragment. Interestingly, we found SLP strongly accelerates the membrane fusion rate when anchored to the target membrane but not the vesicle membrane, suggesting it primarily interacts with t-SNAREs in cis to drive fusion. Furthermore, we determined the SLP fragment is competitive with the full-length Munc18c protein and specific to the cognate v-SNARE isoforms, supporting how it could resemble Munc18c's activity in membrane fusion. Together, our findings demonstrate that Munc18c facilitates SNARE-dependent membrane fusion through SLP, revealing that the t-SNARE-SLP binding mode might be a conserved mechanism for the stimulatory function of SM proteins in vesicle fusion.

A novel bacterial strain of the family ‘Vicingaceae’ was isolated from mangrove of Tielu Harbour, Hainan, PR China. Strain S-15T was a Gram-stain-negative, short-rod-shaped, yellow-pigmented that could grow at 10–42 °C (optimum, 26–35 °C), at pH 5.0–9.0 (optimum, pH 5.5) and in 0.5–10.0 % w/v sea salt (optimum, 3.5–4.0 %). Cells of strain S-15T were 0.9–1.4 µm long, 0.8–0.9 µm wide, catalase-positive and oxidase-positive. Colonies on modified marine agar 2216 were 0.5–2.0 mm in diameter after incubation for 72 h at 28 °C. Analysis of 16S rRNA gene sequences revealed that strain S-15T was most closely related to Vicingus serpentipes ANORD5T (89.8 %). The major respiratory quinone of strain S-15T was menaquinone MK-7, and the dominant fatty acids were C15:0 iso, C15:1 iso G and C17:0 iso 3-OH. The major polar lipids were two unidentified aminolipids, phosphatidylethanolamine and six unidentified lipids. Analyses showed that the genome size was 3.52 Mb and the DNA G+C content was 35.6 mol%, which were higher than V. serpentipes ANORD5T with 2.92 Mb genome size and 31.0 mol% G+C content, respectively. Based on morphological, physiological and phylogenetic data, strain S-15T is considered a type strain of a new species and a new genus of the family ‘Vicingaceae’ for which the name Acidiluteibacter ferrifornacis gen. nov., sp. nov. is proposed. The type strain of Acidiluteibacter ferrifornacis is S-15T (=MCCC 1K03817T=JCM 33804T).

The endoplasmic reticulum (ER) forms direct membrane contact sites with the plasma membrane (PM) in eukaryotic cells. These ER-PM contact sites play essential roles in lipid homeostasis, ion dynamics, and cell signaling, which are carried out by protein-protein or protein-lipid interactions. Distinct tethering factors dynamically control the architecture of ER-PM junctions in response to intracellular signals or external stimuli. The physiological roles of ER-PM contact sites are dependent on a variety of regulators that individually or cooperatively perform functions in diverse cellular processes. This review focuses on proteins functioning at ER-PM contact sites and highlights the recent progress in their mechanisms and physiological roles.

Membrane contact sites (MCSs) formed between the endoplasmic reticulum (ER) and the plasma membrane (PM) provide a platform for nonvesicular lipid exchange. The ER-anchored tricalbins (Tcb1, Tcb2, and Tcb3) are critical tethering factors at ER–PM MCSs in yeast. Tricalbins possess a synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain and multiple Ca2+-binding C2 domains. Although tricalbins have been suggested to be involved in lipid exchange at the ER–PM MCSs, it remains unclear whether they directly mediate lipid transport. Here, using in vitro lipid transfer assays, we discovered that tricalbins are capable of transferring phospholipids between membranes. Unexpectedly, while its lipid transfer activity was markedly elevated by Ca2+, Tcb3 constitutively transferred lipids even in the absence of Ca2+. The stimulatory activity of Ca2+ on Tcb3 required intact Ca2+-binding sites on both the C2C and C2D domains of Tcb3, while Ca2+-independent lipid transport was mediated by the SMP domain that transferred lipids via direct interactions with phosphatidylserine and other negatively charged lipid molecules. These findings establish tricalbins as lipid transfer proteins, and reveal Ca2+-dependent and -independent lipid transfer activities mediated by these tricalbins, providing new insights into their mechanism in maintaining PM integrity at ER–PM MCSs.

Qu Wanli once wrote, “Of all the Classics, the Documents is the most difficult to put in good order.” In an attempt to untangle the complex, often contradictory statements about that text found in pre-Han, Han, and immediately post-Han sources, this article takes on a seemingly minor part of the larger puzzle requiring resolution: did there exist during pre-Han and Han times a preface/postface (xu 序) to a 100-pian Documents, representing a compilation by Kongzi (Confucius) himself that passed down uninterruptedly for centuries within the Kong family? Clearly, if such a work existed, it would have served as a supremely authoritative guide for how to read the classic, and hence a reliable witness to the entire history of the distant Chinese past with its many sage-kings and worthy ministers. Contra much recent scholarship devoted to the so-called 100-pian xu, this article adopts the view that no such genuinely early xu existed for the Documents. 摘要: 《尚書》歷來是儒家五經中糾紛最多、最難讀通的一部。本文僅嘗試對其中 一個小問題進行探索：是否存在一部由孔子編纂並在孔氏家族內部一直流傳到漢 代的百篇《書序》？如果存在，它無疑會是人們讀經的權威指導和三代歷史的可信 見證。但我們得出的結論是否定的。