14 research outputs found
Gause's principle against Dennis Meadow’s findings
The work shows that the Gause’s principle of competitive population displacement can be violated, thus confirming the existence of competition with balancing. Competition with balancing can be analogous to the principle of sustainable development announced in the ideas of Jay Wright Forrester, Dennis L. Meadows and Jorgen Randers on global environmental systems. It is likely that competition with balancing cannot exist for a long time without external management
How Tlg2p/syntaxin 16 ‘snares’ Vps45
Soluble N-ethylmaleimide sensitive factor-attachment protein receptors (SNAREs) and Sec1p/Munc18-homologs (SM proteins) play key roles in intracellular membrane fusion. The SNAREs form tight four-helix bundles (core complexes) that bring the membranes together, but it is unclear how this activity is coupled to SM protein function. Studies of the yeast trans-Golgi network (TGN)/endosomal SNARE complex, which includes the syntaxin-like SNARE Tlg2p, have suggested that its assembly requires activation by binding of the SM protein Vps45p to the cytoplasmic region of Tlg2p folded into a closed conformation. Nuclear magnetic resonance and biochemical experiments now show that Tlg2p and Pep12p, a late- endosomal syntaxin that interacts functionally but not directly with Vps45p, have a domain structure characteristic of syntaxins but do not adopt a closed conformation. Tlg2p binds tightly to Vps45p via a short N-terminal peptide motif that is absent in Pep12p. The Tlg2p/Vps45p binding mode is shared by the mammalian syntaxin 16, confirming that it is a Tlg2p homolog, and resembles the mode of interaction between the SM protein Sly1p and the syntaxins Ufe1p and Sed5p. Thus, this mechanism represents the most widespread mode of coupling between syntaxins and SM proteins
A Munc13/RIM/Rab3 tripartite complex: from priming to plasticity?
α-RIMs and Munc13s are active zone proteins that control priming of synaptic vesicles to a readily releasable state, and interact with each other via their N-terminal sequences. The α-RIM N-terminal sequence also binds to Rab3s (small synaptic vesicle GTPases), an interaction that regulates presynaptic plasticity. We now demonstrate that α-RIMs contain adjacent but separate Munc13- and Rab3-binding sites, allowing formation of a tripartite Rab3/RIM/Munc13 complex. Munc13 binding is mediated by the α-RIM zinc-finger domain. Elucidation of the three-dimensional structure of this domain by NMR spectroscopy facilitated the design of a mutation that abolishes α-RIM/Munc13 binding. Selective disruption of this interaction in the calyx of Held synapse decreased the size of the readily releasable vesicle pool. Our data suggest that the ternary Rab3/RIM/Munc13 interaction approximates synaptic vesicles to the priming machinery, providing a substrate for presynaptic plasticity. The modular architecture of α-RIMs, with nested binding sites for Rab3 and other targets, may be a general feature of Rab effectors that share homology with the α-RIM N-terminal sequence