Parasitic worms hijack key plant protein to build their nest

Parasitic nematode worms infect a variety of crop plants worldwide. Roots infected by these worms start to look rather unsavory – with knot like tumors (galls) developing all over them. At the core of each gall, a worm matures and lays its eggs. Olmo et al. (2018) looked into the developmental reprogramming that leads to gall formation and found an Arabidopsis protein to be a necessary component in this process.     

Taxoid from the needles of the Himalayan yew Taxus wallichiana with cytotoxic and immunomodulatory activities

The needles of Taxus wallichiana gave a taxoid 1-hydroxy- 2-deacetoxy-5-decinnamoyl-taxinine j, whose structure has been established by spectroscopic data and confirmed by X-ray crystallography. The taxoid possesses significant cytotoxic and immunomodulatory activity.     

5'-Modified pyrimidine nucleosides as inhibitors of ribonuclease A

Four 5′-deoxy-5′-nipecotic acid substituted pyrimidine nucleosides were synthesized and characterized. Their inhibitory activities towards ribonuclease A (RNase A) have been studied by enzyme kinetics and docking experiments. All inhibition constants obtained were in the sub-millimolar range. Biochemical analysis shows that the uridine derivative is more potent than the corresponding thymidine derivatives and that the inhibition is competitive in nature. For thymidine derivatives, the 3′-hydroxy group plays an important role in binding as well as in inhibition. Docking studies also support the experimental results. In the docking conformation the uridine derivative was found to bind to the P₁P₂ subsite with the acid group within hydrogen bonding distance of the active site histidine residues.     

The permeability of the endoplasmic reticulum is dynamically coupled to protein synthesis

Proteins synthesized by the rough endoplasmic reticulum (RER) co-translationally cross the membrane through the pore of a ribosome-bound translocon (RBT) complex. Although this pore is also permeable to small molecules, it is generally thought that barriers to their permeation prevent the cyclical process of protein translation from affecting the permeability of the RER. We tested this hypothesis by culturing Chinese hamster ovary-S cells with inhibitors of protein translation that affect the occupancy of RBTs by nascent proteins and then permeabilizing the plasma membrane and measuring the permeability of the RER to a small molecule, 4-methyl-umbelliferyl-alpha-d-glucopyranoside (4-MalphaG). The premature or normal release of nascent proteins by puromycin or pactamycin, respectively, increased the permeability of the RER to 4-MalphaG by 20-30%. In contrast, inhibition of elongation and the release of nascent proteins by cycloheximide did not increase the permeability, but it prevented the increase in permeability by pactamycin. We conclude that the permeability of the RER is coupled to protein translation by a simple gating mechanism whereby a nascent protein blocks the pore of a RBT during translation, but after release of the nascent protein the pore is permeable to small molecules as long as an empty ribosome remains bound to the translocon.