Structural basis of prokaryotic ubiquitin-like protein engagement and translocation by the mycobacterial Mpa-proteasome complex

Proteasomes are present in eukaryotes, archaea and Actinobacteria, including the human pathogen Mycobacterium tuberculosis, where proteasomal degradation supports persistence inside the host. In mycobacteria and other members of Actinobacteria, prokaryotic ubiquitin-like protein (Pup) serves as a degradation tag post-translationally conjugated to target proteins for their recruitment to the mycobacterial proteasome ATPase (Mpa). Here, we use single-particle cryo-electron microscopy to determine the structure of Mpa in complex with the 20S core particle at an early stage of pupylated substrate recruitment, shedding light on the mechanism of substrate translocation. Two conformational states of Mpa show how substrate is translocated stepwise towards the degradation chamber of the proteasome core particle. We also demonstrate, in vitro and in vivo, the importance of a structural feature in Mpa that allows formation of alternating charge-complementary interactions with the proteasome resulting in radial, rail-guided movements during the ATPase conformational cycle.

Coordination of movement via complementary interactions of leaders and followers in termite mating pairs

In collective animal motion, coordination is often achieved by feedback between leaders and followers. For stable coordination, a leader's signals and a follower's responses are hypothesized to be attuned to each other. However, their roles are difficult to disentangle in species with highly coordinated movements, hiding potential diversity of behavioural mechanisms for collective behaviour. Here, we show that two Coptotermes termite species achieve a similar level of coordination via distinct sets of complementary leader–follower interactions. Even though C. gestroi females produce less pheromone than C. formosanus , tandem runs of both species were stable. Heterospecific pairs with C. gestroi males were also stable, but not those with C. formosanus males. We attributed this to the males' adaptation to the conspecific females; C. gestroi males have a unique capacity to follow females with small amounts of pheromone, while C. formosanus males reject C. gestroi females as unsuitable but are competitive over females with large amounts of pheromone. An information-theoretic analysis supported this conclusion by detecting information flow from female to male only in stable tandems. Our study highlights cryptic interspecific variation in movement coordination, a source of novelty for the evolution of social interactions.

Experience Using Electrochemical Noise for Testing Green Corrosion Inhibitors

‘Green’ corrosion inhibitors derived from plant materials provide environmentally friendly alternatives to conventional corrosion inhibitors. They are also much cheaper if using a biomass waste stream or abundant plant material as the source material. There are many examples in literature of different trials, from henna leaves to celery seeds to banana peel. Although it is known that extracts contain electron-rich polar atoms such as N, O, S and P which make them potentially effective inhibitors, it is difficult to predict on a molecular basis what will work well and what will not, since many interacting factors may be at play in complementary interactions. To assist in predicting the inhibition efficiency of inhibitors under varying conditions and choosing the most effective, what is needed is a short-term test which will obviate the need for tedious weight loss experiments. The Electrochemical Noise Method (ENM) uses the natural fluctuations which arise during electrochemical activity to gain information about the corrosion process. Using ENM is quick and non-intrusive method which makes it ideal for screening. Hence a rig has been designed and manufactured which allows for measurement to be made in stirred as well as static conditions and minimises the occurrence of crevice corrosion at the electrodes. Crevice corrosion is a hazard for ENM electrodes when trying to make a comparison with corrosion inhibition calculated using the standard weight loss measurement after immersion (WLM) method. For these preliminary trials we are exploring corrosion of mild steel in HCl in both stirred and unstirred conditions at room temperature. Results are presented comparing ENM measurements with conventional WLM for both Propargyl Alcohol (a conventional industrial corrosion inhibitor) and broccoli extract. Our results suggest that stirring does not make any difference to the noise measured in ENM. The amount of material lost calculated by ENM and WLM (Rn and weight loss values) can be directly compared and show close comparison. It seems likely that as a way of assessing inhibitors quickly (which is particularly important in the testing of "green" inhibitors) that this ENM approach has a lot to offer.

Coordination of movement via complementary interactions of leaders and followers in termite mating pairs

Leadership of animal group movements depends on social feedback, hence leader’s signals and follower’s responses should be attuned to each other. However, leader and follower roles are difficult to disentangle in species with high levels of coordination. To overcome this challenge, we investigated a simple case of movement coordination: termite pairs in which a female leads a male as they search for a nest site. To tease apart leader and follower roles, we created conspecific and heterospecific pairs of Coptotermes gestroi and C. formosanus, which share a pairing pheromone so that males follow females of either species. Conspecific pairs were stable for both species, even though C. gestroi females produce less pheromone than C. formosanus. Heterospecific pairs with C. gestroi males were also stable, but not those with C. formosanus males. We attributed this difference to the C. gestroi male’s unique capacity to follow females that release small amounts of pheromone; C. formosanus males cannot follow or reject C. gestroi females as unsuitable. This conclusion was supported by an information-theoretic analysis that detected information flow from C. formosanus females to C. gestroi males as in conspecific pairs, but not from C. gestroi females to C. formosanus males. Despite their following ability, C. gestroi males lost to C. formosanus males in competitions to follow C. formosanus females. Thus, partner selection has shaped the species-specific association of mating pairs. Our results demonstrate that a similar level of coordination can emerge from distinct sets of complementary sender-receiver interactions.

Modernizing the Philosophy of Creative Creativity

Fang Dongmei (1899–1977) is among the most influential Chinese philosophers who lived and worked in Taiwan during the second half of the 20th century. The present article aims to clarify his view on the basic nature of the human Self. This assessment is more multifaceted than it seems at a first glimpse, for Fang’s philosophy is also more complex than it seems. As a member of the so-called neo-conservative streams of thought, he criticized the Western-type modernization and aimed to revive the holistic onto-epistemology of classical Confucianism. On the other hand, he highlighted the importance of its basic paradigm which underlay the Confucian discourses from their very beginning, i.e. since the Book of Changes, namely the principle of creative creativity (shengshengbuxi 生生不息). The alleged contradiction between his advocating of holism and creativity, has been reflected in the apparent dichotomy between the social and relational essence of the Confucian Moral Self on the one side, and individual uniqueness on the other. The paper aims to show that both seeming contradictions are actually parts of the same theoretical principle defining the complementary interactions of binary oppositions.