Microtubules are regulated by posttranslational modifications (PTMs) of tubulin. The ligation and cleavage of the C-terminal tyrosine of α tubulin impact microtubule functions during mitosis, cardiomyocyte contraction, and neuronal processes. Tubulin tyrosination and detyrosination are mediated by tubulin tyrosine ligase (TTL) and the recently discovered tubulin detyrosinases, vasohibin 1 and 2 (VASH1 and VASH2) bound to the small vasohibin-binding protein (SVBP). Here, we report the crystal structures of human VASH1–SVBP alone, in complex with a tyrosine-derived covalent inhibitor, and bound to the natural product parthenolide. The structures and subsequent mutagenesis analyses explain the requirement for SVBP during tubulin detyrosination, and reveal the basis for the recognition of the C-terminal tyrosine and the acidic α tubulin tail by VASH1. The VASH1–SVBP–parthenolide structure provides a framework for designing more effective chemical inhibitors of vasohibins, which can be valuable for dissecting their biological functions and may have therapeutic potential.

Highlights d The crystal structure of human Spartan bound to DNA is determined d The SprT domain contains a Zn 2+-binding subdomain that binds single-stranded DNA d DNA engages two Spartan molecules with a conserved dimer interface in the crystal d DNA positions the SprT domain for optimal cleavage of DNAprotein crosslinks

The spindle checkpoint maintains genomic stability and prevents aneuploidy. Unattached kinetochores convert the latent open conformer of the checkpoint protein Mad2 (O-Mad2) to the active closed conformer (C-Mad2), bound to Cdc20. C-Mad2–Cdc20 is incorporated into the mitotic checkpoint complex (MCC), which inhibits the anaphase-promoting complex/cyclosome (APC/C). The C-Mad2-binding protein p31comet and the ATPase TRIP13 promote MCC disassembly and checkpoint silencing. Here, using nuclear magnetic resonance (NMR) spectroscopy, we show that TRIP13 and p31comet catalyze the conversion of C-Mad2 to O-Mad2, without disrupting its stably folded core. We determine the crystal structure of human TRIP13, and identify functional TRIP13 residues that mediate p31comet–Mad2 binding and couple ATP hydrolysis to local unfolding of Mad2. TRIP13 and p31comet prevent APC/C inhibition by MCC components, but cannot reactivate APC/C already bound to MCC. Therefore, TRIP13–p31comet intercepts and disassembles free MCC not bound to APC/C through mediating the local unfolding of the Mad2 C-terminal region.

The dynamic tyrosination-detyrosination cycle of α-tubulin regulates microtubule functions. Perturbation of this cycle impairs mitosis, neural physiology, and cardiomyocyte contraction. The carboxypeptidases vasohibins 1 and 2 (VASH1 and VASH2), in complex with the small vasohibin-binding protein (SVBP), mediate α-tubulin detyrosination. These enzymes detyrosinate microtubules more efficiently than soluble αβ-tubulin heterodimers. The structural basis for this substrate preference is not understood. Using cryo-electron microscopy (cryo-EM), we have determined the structure of human VASH1-SVBP bound to microtubules. The acidic C-terminal tail of α-tubulin binds to a positively charged groove near the active site of VASH1. VASH1 forms multiple additional contacts with the globular domain of α-tubulin, including contacts with a second α-tubulin in an adjacent protofilament. Simultaneous engagement of two protofilaments by VASH1 can only occur within the microtubule lattice, but not with free αβ heterodimers. These lattice-specific interactions enable preferential detyrosination of microtubules by VASH1.

The conserved ATPase p97 (Cdc48 in yeast) and adaptors mediate diverse cellular processes through unfolding polyubiquitinated proteins and extracting them from macromolecular assemblies and membranes for disaggregation and degradation. The tandem ATPase domains (D1 and D2) of the p97/Cdc48 hexamer form stacked rings. p97/Cdc48 can unfold substrates by threading them through the central pore. The pore loops critical for substrate unfolding are, however, not well-ordered in substrate-free p97/Cdc48 conformations. How p97/Cdc48 organizes its pore loops for substrate engagement is unclear. Here we show that p97/Cdc48 can form double hexamers (DH) connected through the D2 ring. Cryo-EM structures of p97 DH reveal an ATPase-competent conformation with ordered pore loops. The C-terminal extension (CTE) links neighboring D2s in each hexamer and expands the central pore of the D2 ring. Mutations of Cdc48 CTE abolish substrate unfolding. We propose that the p97/Cdc48 DH captures a potentiated state poised for substrate engagement.

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Background & Aims: In 2017, China launched a pilot state-owned natural resource asset management system in some pilot areas of the national park system, aiming to accumulate experience in the management of important ecological space natural resources such as national parks. On October 12, 2021, President Xi Jinping announced the creation of the first national parks. Therefore, it is of great practical significance to explore the management of natural resources in national parks, and it can provide reference for the future management of resources and environment. In order to summarize the pilot experience and promote the management of natural resources assets in national parks, we investigate the pilot of natural resource management system in national parks. Progress: The results indicated that the management of natural resources in the national park pilots has made progress in the institutional setup, local legislation, and with distribution of powers and responsibilities. In terms of the organizational framework, China has built three forms of national park management, including central vertical management, central and local joint management, and local management. The provincial legislature issued five laws and regulations for national parks that inform matters such as natural resources investigation and registration, natural resources inventory, and the prohibited behavior of natural resources, which provides a legal basis for national park managers. The Nanshan, Shennongjia and Wuyishan national park services have issued a list of powers and responsibilities to clarify the division of responsibilities. However, there are still some problems with the national parks,•保护与治理对策•

Aims: Wildlife population monitoring projects provide important insight and basis for species research and conservation efforts. The snow leopard (Panthera uncia), as the top predator and flagship species of Asian mountainous ecosystems, is of great scientific and conservation interest. However, due to its remote habitat, elusive behavior and large home ranges, long-term population monitoring study on snow leopards is rarely reported. Here we report a long-term population monitoring project of snow leopards in Sanjiangyuan National Nature Reserve (Yunta Village, Haxiu Township, Yushu Prefecture, Qinghai Province) from Oct. 2013 to Jan. 2019. Methods: We monitored the population using infrared cameras maintained by the local community. We estimated population size and density as well as population growth rate using spatially explicit capture-recapture model (SECR). We calculated population turnover rates and analyzed territory replacement.