Structure of cryptophyte photosystem II-light-harvesting antennae supercomplex.

Cryptophytes are ancestral photosynthetic organisms evolved from red algae through secondary endosymbiosis. They have developed alloxanthin-chlorophyll a/c2-binding proteins (ACPs) as light-harvesting complexes (LHCs). The distinctive properties of cryptophytes contribute to efficient oxygenic photosynthesis and underscore the evolutionary relationships of red-lineage plastids.

Architecture of symbiotic dinoflagellate photosystem I-light-harvesting supercomplex in Symbiodinium.

Symbiodinium are the photosynthetic endosymbionts for corals and play a vital role in supplying their coral hosts with photosynthetic products, forming the nutritional foundation for high-yield coral reef ecosystems. Here, we determine the cryo-electron microscopy structure of Symbiodinium photosystem I (PSI) supercomplex with a PSI core composed of 13 subunits including 2 previously unidentified subunits, PsaT and PsaU, as well as 13 peridinin-Chl a/c-binding light-harvesting antenna proteins (AcpPCIs). The PSI-AcpPCI supercomplex exhibits distinctive structural features compared to their red lineage counterparts, including extended termini of PsaD/E/I/J/L/M/R and AcpPCI-1/3/5/7/8/11 subunits, conformational changes in the surface loops of PsaA and PsaB subunits, facilitating the association between the PSI core and peripheral antennae.

A novel class of xylanases specifically degrade marine red algal β1,3/1,4-mixed-linkage xylan.

Xylans are polysaccharides composed of xylose and include β1,4-xylan, β1,3-xylan, and β1,3/1,4-mixed-linkage xylan (MLX). MLX is widely present in marine red algae and constitutes a significant organic carbon in the ocean. Xylanases are hydrolase enzymes that play an important role in xylan degradation.

Structural basis and evolution of the photosystem I-light-harvesting supercomplex of cryptophyte algae.

Cryptophyte plastids originated from a red algal ancestor through secondary endosymbiosis. Cryptophyte photosystem I (PSI) associates with transmembrane alloxanthin-chlorophyll a/c proteins (ACPIs) as light-harvesting complexes (LHCs). Here, we report the structure of the photosynthetic PSI-ACPI supercomplex from the cryptophyte Chroomonas placoidea at 2.

Native architecture and acclimation of photosynthetic membranes in a fast-growing cyanobacterium.

Efficient solar energy conversion is ensured by the organization, physical association, and physiological coordination of various protein complexes in photosynthetic membranes. Here, we visualize the native architecture and interactions of photosynthetic complexes within the thylakoid membranes from a fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 (Syn2973) using high-resolution atomic force microscopy. In the Syn2973 thylakoid membranes, both photosystem I (PSI)-enriched domains and crystalline photosystem II (PSII) dimer arrays were observed, providing favorable membrane environments for photosynthetic electron transport.

A study of the protein-protein interactions in the phycocyanin monomer from sp PCC 6803 using a bacterial two-hybrid system.

Investigations into the intramolecular interactions of the native protein in solution are important to understand its structural stability as well as its potential uses in future applications. In this study, we used a bacterial two-hybrid system to investigate the interaction between the phycocyanin α and β subunits that form the phycocyanin monomer. Key amino acid residues responsible for the interaction between the subunits were identified, providing direct experimental evidence for the intramolecular interaction.

Characterizing the supercomplex association of photosynthetic complexes in cyanobacteria.

The light reactions of photosynthesis occur in thylakoid membranes that are densely packed with a series of photosynthetic complexes. The lateral organization and close association of photosynthetic complexes in native thylakoid membranes are vital for efficient light harvesting and energy transduction. Recently, analysis of the interconnections between photosynthetic complexes to form supercomplexes has garnered great interest.

Altered -glycan composition impacts flagella-mediated adhesion in .

For the unicellular alga the presence of -glycosylated proteins on the surface of two flagella is crucial for both cell-cell interaction during mating and flagellar surface adhesion. However, it is not known whether only the presence or also the composition of -glycans attached to respective proteins is important for these processes. To this end, we tested several insertional mutants and a CRISPR/Cas9 knockout mutant of xylosyltransferase 1A, all possessing altered -glycan compositions.

Structural Visualization of Septum Formation in Staphylococcus warneri Using Atomic Force Microscopy.

Cell division of adopts a "popping" mechanism that mediates extremely rapid separation of the septum. Elucidating the structure of the septum is crucial for understanding this exceptional bacterial cell division mechanism. Here, the septum structure of was extensively characterized using high-speed time-lapse confocal microscopy, atomic force microscopy, and electron microscopy.

Structural variability, coordination and adaptation of a native photosynthetic machinery.

Cyanobacterial thylakoid membranes represent the active sites for both photosynthetic and respiratory electron transport. We used high-resolution atomic force microscopy to visualize the native organization and interactions of photosynthetic complexes within the thylakoid membranes from the model cyanobacterium Synechococcus elongatus PCC 7942. The thylakoid membranes are heterogeneous and assemble photosynthetic complexes into functional domains to enhance their coordination and regulation.

Unfolding pathway and intermolecular interactions of the cytochrome subunit in the bacterial photosynthetic reaction center.

Precise folding of photosynthetic proteins and organization of multicomponent assemblies to form functional entities are fundamental to efficient photosynthetic electron transfer. The bacteriochlorophyll b-producing purple bacterium Blastochloris viridis possesses a simplified photosynthetic apparatus. The light-harvesting (LH) antenna complex surrounds the photosynthetic reaction center (RC) to form the RC-LH1 complex.

sp. nov., a psychrotolerant bacterium isolated from Arctic brown algae.

A Gram-stain-negative, facultatively anaerobic, flagellated and rod-shaped bacterium, designated strain SM1901, was isolated from a brown algal sample collected from Kings Bay, Svalbard, Arctic. Strain SM1901 grew at -4‒30 °C and with 0-7.0 % (w/v) NaCl.

A Novel Subfamily of Endo-β-1,4-Glucanases in Glycoside Hydrolase Family 10.

As classified by the Carbohydrate-Active Enzymes (CAZy) database, enzymes in glycoside hydrolase (GH) family 10 (GH10) are all monospecific or bifunctional xylanases (except a tomatinase), and no endo-β-1,4-glucanase has been reported in the family. Here, we identified carboxymethyl cellulase (CMCase) as a GH10 endo-β-1,4-glucanase. CMCase originated from an Arctic marine bacterium, SM1504 It shows low identity (<35%) with other GH10 xylanases.

Self-Assembly Stability and Variability of Bacterial Microcompartment Shell Proteins in Response to the Environmental Change.

Bacterial microcompartments (BMCs) are proteinaceous self-assembling organelles that are widespread among the prokaryotic kingdom. By segmenting key metabolic enzymes and pathways using a polyhedral shell, BMCs play essential roles in carbon assimilation, pathogenesis, and microbial ecology. The BMC shell is composed of multiple protein homologs that self-assemble to form the defined architecture.

Atomic Force Microscopy of Side Wall and Septa Peptidoglycan From Reveals an Architectural Remodeling During Growth.

Peptidoglycan is the fundamental structural constituent of the bacterial cell wall. Despite many years of research, the architecture of peptidoglycan is still largely elusive. Here, we report the high-resolution architecture of peptidoglycan from the model Gram-positive bacterium .

Supramolecular architecture of photosynthetic membrane in red algae in response to nitrogen starvation.

The availability of nitrogen is one of the most important determinants that can limit the growth of photosynthetic organisms including plants and algae; however, direct observations on the supramolecular architecture of photosynthetic membranes in response to nitrogen stress are still lacking. Red algae are an important evolutionary group of algae which contain phycobilisomes (PBSs) on their thylakoid membranes, as do cyanobacteria. PBSs function not only as light-harvesting antennae but also as nitrogen storage.

Development of fluorogenic probe-based and high-resolution melting-based polymerase chain reaction assays for the detection and differentiation of Bartonella quintana and Bartonella henselae.

Bartonella henselae and Bartonella quintana are the major etiological agents of infective endocarditis, which pose a serious threat to human health. To simultaneously detect and differentiate B. henselae and B.

A novel process for recovery of iron, titanium, and vanadium from titanomagnetite concentrates: NaOH molten salt roasting and water leaching processes.

A novel process for recovering iron, titanium, and vanadium from titanomagnetite concentrates has been developed. In the present paper, the treatment of rich titanium-vanadium slag by NaOH molten salt roasting and water leaching processes is investigated. In the NaOH molten salt roasting process, the metallic iron is oxidized into ferriferous oxide, MgTi(2)O(5) is converted to NaCl-type structure of Na(2)TiO(3), and M(3)O(5) (M=Ti, Mg, Fe) is converted to α-NaFeO(2)-type structure of NaMO(2), respectively.