Dual protection by Bcp1 and Rkm1 ensures incorporation of uL14 into pre-60S ribosomal subunits.

Eukaryotic ribosomal proteins contain extended regions essential for translation coordination. Dedicated chaperones stabilize the associated ribosomal proteins. We identified Bcp1 as the chaperone of uL14 in Saccharomyces cerevisiae. Rkm1, the lysine methyltransferase of uL14, forms a ternary complex with Bcp1 and uL14 to protect uL14. Rkm1 is transported with uL14 by importins to the nucleus, and Bcp1 disassembles Rkm1 and importin from uL14 simultaneously in a RanGTP-independent manner. Molecular docking, guided by crosslinking mass spectrometry and validated by a low-resolution cryo-EM map, reveals the correlation between Bcp1, Rkm1, and uL14, demonstrating the protection model. In addition, the ternary complex also serves as a surveillance point, whereas incorrect uL14 is retained on Rkm1 and prevented from loading to the pre-60S ribosomal subunits. This study reveals the molecular mechanism of how uL14 is protected and quality checked by serial steps to ensure its safe delivery from the cytoplasm until its incorporation into the 60S ribosomal subunit.

Effects of management intensities on soil aggregate stability and carbon, nitrogen, phosphorus distribution in Phyllostachys edulis forests.

Soil aggregates are the main sites for the decomposition of soil organic matter and the formation of humus. The composition characteristics of aggregates with different particle sizes are one of the indicators for soil fertility. We explored the effects of management intensity (frequency of fertilization and reclamation) on soil aggregates in moso bamboo forests, including mid-intensity management (T1, fertilization and reclamation every 4 years), high-intensity management (T2, fertilization and reclamation every 2 years), and extensive management (CK). The water-stable soil aggregates (0-10, 10-20, and 20-30 cm layers) from moso bamboo forest were separated by a combination of dry and wet sieving method and the distribution of soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (AP) across different soil layers were determined. The results showed that management intensities had significant effects on soil aggregate composition and stability, and SOC, TN, AP distribution of moso bamboo forests. Compared with CK, T1 and T2 decreased the proportion and stability of macroaggregates in 0-10 cm soil layer, but increased that in 20-30 cm soil layer, while reduced the content of organic carbon in macroaggregates, the contents of organic carbon, TN and AP in microaggregates. Such results indicated that the intensified management was not conducive to formation of macroaggregates in 0-10 cm soil layer and carbon sequestration in macroaggregates. It was beneficial to the accumulation of organic carbon in soil aggregates and nitrogen and phosphorus in microaggregates with lower human disturbance. Mass fraction of macroaggregates and organic carbon content of macroaggregates was significantly positively correlated with aggregate stability, which best explained the variations of aggregate stability. Therefore, macroaggregates and organic carbon content of macroaggregates were the most important factors affecting the formation and stability of aggregates. Appropriate reduction of disturbance was beneficial to the accumulation of macroaggregates in the topsoil, the sequestration of organic carbon by macro-aggregates, and the sequestration of TN and AP by microaggregates, and improving soil quality and sustainable management in moso bamboo forest from the point of view of soil aggregate stability.