CAMSAP and Patronin family members regulate microtubule minus-end stability and localization and thus organize non-centrosomal microtubule networks, which are essential for cell division, polarization and differentiation. Here, we show that the C-terminal CKK domain of CAMSAPs is widely present among eukaryotes and autonomously recognizes microtubule minus ends. Through a combination of structural approaches, we uncover how mammalian CKK binds between two tubulin dimers at the inter-protofilament interface on the outer microtubule surface. In vitro reconstitution assays combined with high resolution fluorescence microscopy and cryo-electron tomography suggest that CKK preferentially associates with the transition zone between curved protofilaments and the regular microtubule lattice. We propose that minus-end-specific features of the inter-protofilament interface at this site form the basis for CKK’s minus-end preference. The steric clash between microtubule-bound CKK and kinesin motors explains how CKK protects microtubule minus ends against kinesin-13-induced depolymerization and thus controls the stability of free microtubule minus ends.

CAMSAP/Patronins regulate microtubule minus-end dynamics. Their end specificity is mediated by their CKK domains, which we proposed recognise specific tubulin conformations found at minus ends. To critically test this idea, we compared the human CAMSAP1 CKK domain (HsCKK) with a CKK domain from Naegleria gruberi (NgCKK), which lacks minus-end specificity. Here we report near-atomic cryo-electron microscopy structures of HsCKK- and NgCKK-microtubule complexes, which show that these CKK domains share the same protein fold, bind at the intradimer interprotofilament tubulin junction, but exhibit different footprints on microtubules. NMR experiments show that both HsCKK and NgCKK are remarkably rigid. However, whereas NgCKK binding does not alter the microtubule architecture, HsCKK remodels its microtubule interaction site and changes the underlying polymer structure because the tubulin lattice conformation is not optimal for its binding. Thus, in contrast to many MAPs, the HsCKK domain can differentiate subtly specific tubulin conformations to enable microtubule minus-end recognition.

Liquid–liquid phase separation is increasingly recognized as a process involved in cellular organization. Thus far, a detailed structural characterization of this intrinsically heterogeneous process has been challenging. Here we combine solid- and solution-state NMR spectroscopy to obtain atomic-level insights into the assembly and maturation of cytoplasmic processing bodies that contain mRNA as well as enzymes involved in mRNA degradation. In detail, we have studied the enhancer of decapping 3 (Edc3) protein that is a central hub for processing body formation in yeast. Our results reveal that Edc3 domains exhibit diverse levels of structural organization and dynamics after liquid–liquid phase separation. In addition, we find that interactions between the different Edc3 domains and between Edc3 and RNA in solution are largely preserved in the condensed protein state, allowing processing bodies to rapidly form and dissociate upon small alterations in the cellular environment.

Microtubules are important components of the eukaryotic cytoskeleton. Their structural organization is regulated by nucleotide binding and many microtubule-associated proteins (MAPs). While cryo-EM and X-ray crystallography have provided detailed views of interactions between MAPs with the microtubule lattice, little is known about how MAPs and their intrinsically disordered regions interact with the dynamic microtubule surface. NMR carries the potential to directly probe such interactions but so far has been precluded by the low tubulin yield. We present a protocol to produce [13C, 15N]-labeled, functional microtubules (MTs) from human cells for solid-state NMR studies. This approach allowed us to demonstrate that MAPs can differently modulate the fast time-scale dynamics of C-terminal tubulin tails, suggesting distinct interaction modes. Our results pave the way for in-depth NMR studies of protein dynamics involved in MT assembly and their interactions with other cellular components.

CAMSAP/Patronins regulate microtubule minus-end dynamics. Their end specificity is mediated by their CKK domains, which we proposed recognise specific tubulin conformations found at minus ends. To critically test this idea, we compared the human CAMSAP1 CKK domain (HsCKK) with a CKK domain from Naegleria gruberi (NgCKK), which has lost minus-end specificity. Near-atomic cryo-electron microscopy structures of HsCKK-and NgCKK-microtubule complexes show that these CKK domains share the same protein fold, bind at the intradimer interprotofilament tubulin junction, but exhibit subtly different footprints on microtubules. Whereas NgCKK binding does not alter the microtubule architecture, HsCKK remodels its microtubule interaction site and changes the underlying polymer structure because the tubulin lattice conformation is not optimal for its binding. NMR experiments show that HsCKK is remarkably rigid, supporting this remodelling ability. Thus, in contrast to many MAPs, CKK domains can differentiate subtly specific tubulin conformations to enable microtubule minus-end recognition.

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This study selected and tested five submerged aquatic vegetation‐based (SAV) wetlands to improve highway runoff treatment in best management practices. The removal efficiencies of suspended solid (SS), chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4+-N), and total phosphorus (TP) in the five SAV wetlands were analyzed. Furthermore, the lead (Pb) and zinc (Zn) accumulation capabilities of five submerged macrophytes were determined. The obtained results show that Ceratophyllum demersum wetlands achieved the highest nutrient removal and had the heavy metal accumulation property. Vallisneria natans showed the highest bioaccumulation of Pb among all tested species. Ceratophyllum demersum wetlands showed the highest average removal efficiencies of SS (82.97%), COD (62.08%), TN (77.63%), NH4+-N (76.24%), TP (77.55%), Pb (96.24%), and Zn (91.23%). The tendencies of contaminant removal showed seasonal variation, and SAV wetlands performed better in summer than in spring and autumn. Consequently, SAV wetlands showed selectivity for contaminant removal. Practitioner points Chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in highway runoff were removed by submerged aquatic vegetation (SAV). Ceratophyllum demersum and Myriophyllum spicatum wetlands performed well on heavy metal removing. Ceratophyllum demersum showed the highest removal efficiencies of TSS, COD, TN, NH4+-N, and TP. The SAV wetlands performed better in summer than in other seasons.