Sentence-Final Particles in Chinese

Chinese has a rich system of Sentence-Final Particles (SFPs). Traditional grammar and descriptive linguistic studies attempt to capture the precise semantic interpretation and the discourse function of each particle. Much work related to this aspect tries to find out what the core semantic interpretation of a given SFP is, how the diverse interpretations of a given SFP are developed from its core interpretation, and in what context the use of a given SFP is licit. Linguists from different disciplines have made important observations and offered various explanations. On the other hand, diachronic studies trace the origin and the evolution of each SFP, which helps understand the core semantics of SFPs in modern Chinese. Studies on different Chinese dialects also help the understanding of the meaning and the function of SFPs from a comparative perspective. Under the generative framework, SFPs are analyzed as complementizers, which are located in the peripheral domain. Both traditional grammarians and generative syntacticians are interested in patterns like the rigid order that necessarily shows whenever SFPs co-occur. They attempt to establish the hierarchical order of SFPs and identify the general principle that regulates such an order. Recent studies show that such an order is regulated by a discourse constraint related to subjectivity, according to which the higher a functional projection is located, the more directly it is for such a projection to be linked to the speaker’s attitude, the more subjective the interpretation of such a projection becomes, and the less likely it is for such a projection to be embedded. This constraint offers an explanation to the question of why only some SFPs can appear in embedded clauses whereas the others demonstrate root properties. Syntacticians are also interested in the question of how to derive the final order of SFPs. Two analyses are available: disjunction analysis and complement-to-specifier raising analysis. A more recent finding is that under the minimalist framework, each SFP heads a phase and bears an EPP feature. Complement-to-specifier raising is required as a last resort to satisfy the Extended Projection Principle (EPP). The complement of an SFP is moved to the phase edge to postpone the transfer of the phrases that are embedded within the complement, which allows these phrases to be extracted later.

Deriving Head-Final Order in the Peripheral Domain of Chinese

This article proposes a unified analysis of the peripheral projections in Chinese, which does not rely on a head-directionality parameter. Each of these projections constitutes a phase and that its head bears an EPP feature, which must be satisfied. Chinese peripheral projections demonstrate four different ways to satisfy EPP. Importantly, Sentence-Final Particles (SFPs) project phases and their complements obligatorily move to the specifier as a last resort to satisfy the EPP. The movement of the complement to the phase edge would postpone the transfer of phrases embedded in the complement, allowing these phrases to move later. When the phase edge is not available for the moved complement, phrases embedded within the complement will not be able to be extracted in the later stage after the complement is transferred. This constitutes a strong argument in favor of the obligatory complement-to-specifier raising analysis for SFPs in Chinese.

Pseudouridine Synthase RsuA Captures an Assembly Intermediate That Is Stabilized by Ribosomal Protein S17

The ribosome is a large ribonucleoprotein complex that synthesizes protein in all living organisms. Ribosome biogenesis is a complex process that requires synchronization of various cellular events, including ribosomal RNA (rRNA) transcription, ribosome assembly, and processing and post-transcriptional modification of rRNA. Ribosome biogenesis is fine-tuned with various assembly factors, possibly including nucleotide modification enzymes. Ribosomal small subunit pseudouridine synthase A (RsuA) pseudouridylates U516 of 16S helix 18. Protein RsuA is a multi-domain protein that contains the N-terminal peripheral domain, which is structurally similar to the ribosomal protein S4. Our study shows RsuA preferably binds and pseudouridylates an assembly intermediate that is stabilized by ribosomal protein S17 over the native-like complex. In addition, the N-terminal domain truncated RsuA showed that the presence of the S4-like domain is important for RsuA substrate recognition.

Interference of pH buffer with Pb2+-peripheral domain interactions: obstacle or opportunity?

ABSTRACTPb2+ is a xenobiotic metal ion that competes for Ca2+-binding sites in proteins. Using the peripheral Ca2+-sensing domains of Syt1, we show that the chelating pH buffer Bis-Tris enables identification and functional characterization of high-affinity Pb2+ sites that are likely to be targeted by bioavailable Pb2+.Significance to MetallomicsSyt1, a key regulator of Ca2+-evoked neurotransmitter release, is a putative molecular target of Pb2+. We demonstrate that the use of a chelating pH buffer Bis-Tris enables identification of Ca2+-binding sites that would be most susceptible to Pb2+ attack in the cellular environment. In addition, experiments conducted in Bis-Tris revealed the differences between the membrane-binding responses of two Ca2+-sensing domains of Syt1, C2A and C2B. This work advances the understanding of how Pb2+ interacts with multipartite Ca2+-binding sites, and illustrates that conducting the experiments under both chelating and non-chelating conditions could provide valuable insight into the mechanism of metallosensory proteins.

Interference of pH buffer with Pb2+-peripheral domain interactions: obstacle or opportunity?

Pb2+-Chelating pH buffer Bis–Tris enables identification of factors that determine the cooperative metal-ion binding response and membrane association of the Synaptotagmin 1 C2 domains.

Lignin-Only Polymeric Materials Based on Unmethylated Unfractionated Kraft and Ball-Milled Lignins Surpass Polyethylene and Polystyrene in Tensile Strength

Functional polymeric materials composed solely of lignin preparations appeared only very recently. A gradual paradigm shift spanning 56 years has revealed how lignin–lignin blends can upgrade the performance of 100 wt% lignin-based plastics. The view, first espoused in 1960, that lignin macromolecules are crosslinked reduces the plausibility of creating functional polymeric materials that are composed only of lignin preparations. Lignin-based materials would be much weaker mechanically if interstices remain in significant numbers between adjoining macromolecular structures that consist of rigid crosslinked chains. In 1982, random-coil features in the hydrodynamic character of kraft lignin (KL) components were evident from ultracentrifugal sedimentation equilibrium studies of their SEC behavior. In 1997, it was recognized that the macromolecular species in plastics with 85 wt% levels of KL are associated complexes rather than individual components. Finally, in 2016, the first polymeric material composed entirely of ball-milled softwood lignin (BML) was found to support a tensile strength above polyethylene. Except in its molecular weight, the BML was similar in structure to the native biopolymer. It was composed of associated lignin complexes, each with aromatic rings arranged in two domains. The inner domain maintains structural integrity largely through noncovalent interactions between cofacially-offset aromatic rings; the peripheral domain contains a higher proportion of edge-on aromatic-ring arrangements. Interdigitation between peripheral domains in adjoining complexes creates material continuity during casting. By interacting at low concentrations with the peripheral domains, non-lignin blend components can improve the tensile strengths of BML-based plastics to values well beyond those seen in polystyrene. The KL-based plastics are weaker because the peripheral domains of adjoining complexes are less capable of interdigitation than those of BML. Blending with 5 wt% 1,8-dinitroanthraquinone results in a tensile strength above that of polyethylene. Analogous effects can be achieved with 10 wt% maple γ-valerolactone (GVL) lignin which, with a structure close to the native biopolymer, imparts some native character to the peripheral domains of the KL complexes. Comparable enhancements in the behavior of BML complexes upon blending with 10 wt% ball-milled corn-stover lignin (BMCSL) result in lignin-only polymeric materials with tensile strengths well beyond polystyrene.

Lipid functions in cytochrome bc complexes: an odd evolutionary transition in a membrane protein structure

Lipid-binding sites and properties were compared in the hetero-oligomeric cytochrome (cyt) b 6 f and the yeast bc 1 complexes that function, respectively, in photosynthetic and respiratory electron transport. Seven lipid-binding sites in the monomeric unit of the dimeric cyanobacterial b 6 f complex overlap four sites in the Chlamydomonas reinhardtii algal b 6 f complex and four in the yeast bc 1 complex. The proposed lipid functions include: (i) interfacial–interhelix mediation between (a) the two 8-subunit monomers of the dimeric complex, (b) between the core domain (cyt b , subunit IV) and the six trans membrane helices of the peripheral domain (cyt f , iron–sulphur protein (ISP), and four small subunits in the boundary ‘picket fence’); (ii) stabilization of the ISP domain-swapped trans-membrane helix; (iii) neutralization of basic residues in the single helix of cyt f and of the ISP; (iv) a ‘latch’ to photosystem I provided by the β-carotene chain protruding through the ‘picket fence’; (v) presence of a lipid and chlorophyll a chlorin ring in b 6 f in place of the eighth helix in the bc 1 cyt b polypeptide. The question is posed of the function of the lipid substitution in relation to the evolutionary change between the eight and seven helix structures of the cyt b polypeptide. On the basis of the known n-side activation of light harvesting complex II (LHCII) kinase by the p-side level of plastoquinol, one possibility is that the change was directed by the selective advantage of p- to n-side trans membrane signalling functions in b 6 f , with the lipid either mediating this function or substituting for the trans membrane helix of a signalling protein lost in crystallization.