The algal PETC-Pro171-Leu suppresses electron transfer in the cytochrome b6f under acidic lumenal condition

Linear photosynthetic electron flow (LEF) produces NADPH and generates a proton electrochemical potential gradient across the thylakoid membrane used to synthesize ATP, both of which are required for CO2 fixation. As cellular demand for ATP and NADPH are variable, cyclic electron flow (CEF) between PSI and cytochrome b6f complex (b6f) produces extra ATP. The b6f regulates LEF and CEF via photosynthetic control, which is a pH-dependent b6f slowdown of plastoquinol oxidation at the lumenal site. This protection mechanism is triggered at more alkaline lumen pH in the pgr1 mutant of the vascular plant Arabidopsis thaliana, carrying Pro194Leu in the b6f Rieske Iron-sulfur protein. In this work, we introduced pgr1 mutation in the green alga Chlamydomonas reinhardtii (PETC-P171L). Consistent with pgr1 phenotype, PETC-P171L displayed a limited photosynthesis along with slower photoautotrophic growth under high light conditions. Our data under low oxygen revealed that the ΔpH component in algae was already sufficient to trigger the effect in PETC-P171L in sub-saturating light conditions where the mutant b6f was more restricted to oxidize the PQ pool and revealed a diminished electron flow.

Role of Sulfur Metabolism Gene and High-Sulfur Gene Expression in Wool Growth Regulation in the Cashmere Goat

Sulfur, an essential mineral element for animals, mainly exists in the form of organic sulfur-containing amino acids (SAAs), such as cystine, methionine, and cysteine, within the body. The content, form, and structure of sulfur play an important role in determining the wool fiber quality. In addition, keratin-associated proteins, one of the most crucial wool fiber components, are rich in SAAs. However, sulfur metabolism from the blood to the skin and hair follicles remains unclear. In this study, we analyzed high-sulfur protein gene and sulfur metabolism genes in the cashmere goat and explored the effects of melatonin on their expression. In total, 53 high-sulfur protein genes and 321 sulfur metabolism genes were identified. We found that high-sulfur protein genes were distributed in the 3–4 and 144M regions of chromosome 1 and the 40–41M region of chromosome 19 in goats. Moreover, all year round, allele-specific expression (ASE) is higher in the 40–41M region of chromosome 19 than in the other regions. Total of 47 high-sulfur protein genes showed interaction with transcription factors and cofactors with ASE. These transcription factors and cofactors were inhibited after melatonin implantation. The network analysis revealed that melatonin may activate the sulfur metabolism process via the regulation of the genes related to cell energy metabolism and cell cycle in the skin, which provided sufficient SAAs for wool and cashmere growth. In conclusion, our findings provide a new insight into wool growth regulation by sulfur metabolism genes and high-sulfur protein genes in cashmere goats.

Higher NDUFS8 Serum Levels Correlate with Better Insulin Sensitivity in Type 1 Diabetes

Aim: The aim of the study was to evaluate the function of Complex I by measuring NADH dehydrogenase [ubiquinone] iron-sulfur protein 8 serum level and the relationship with insulin resistance in type 1 diabetes. T1DM causes adverse changes in the mitochondria, which can influence the development of chronic complications. The NADH dehydrogenase [ubiquinone] iron-sulfur protein 8 (NDUFS8 protein) is a subunit of NADH dehydrogenase and plays an important role in the mitochondrial function. NDUFS8 serum concentration probably reflects the function of mitochondria. Methods: All of 36 people suffer from T1DM. All participants were treated with functional intensive insulin therapy. NDUFS8 protein serum concentration was measured using the ELISA test. Insulin resistance was evaluated with indirect marker estimated glucose disposal rate (eGDR). The group was divided on the base of median value of eGDR (higher eGDR – less IR). Results: The study group consisted of 12 women and 24 men, aged 39.5 (28.0-46.5) years with the duration of the disease 22 (15-26) years. Medians of eGDR and NDUFS8 protein concentration were 7.6 (5.58-8.99) mg/kg/min and 2.25 (0.72-3.81) ng/ml, respectively. The group with higher insulin sensitivity had higher NDUFS8 protein serum concentration, lower WHR, BMI and they were younger. A negative correlation was observed between NDUFS8 protein serum concentration and WHR (rs=-0.35,p=0.03), whereas a positive correlation was observed between NDUFS8 protein serum concentration and eGDR (rs=0.43,p=0.008). Multivariate linear regression confirmed a significant association between insulin sensitivity and better mitochondrial function (beta=0.54,p=0.003), independent of age, duration of diabetes and smoking. Conclusions: Higher NDUFS8 protein serum concentration is associated with higher insulin sensitivity among people with T1DM and might reflects better mitochondrial function.

Crystal structure of a photosynthetic LH1-RC in complex with its electron donor HiPIP

Photosynthetic electron transfers occur through multiple components ranging from small soluble proteins to large integral membrane protein complexes. Co-crystallization of a bacterial photosynthetic electron transfer complex that employs weak hydrophobic interactions was achieved by using high-molar-ratio mixtures of a soluble donor protein (high-potential iron-sulfur protein, HiPIP) with a membrane-embedded acceptor protein (reaction center, RC) at acidic pH. The structure of the co-complex offers a snapshot of a transient bioenergetic event and revealed a molecular basis for thermodynamically unfavorable interprotein electron tunneling. HiPIP binds to the surface of the tetraheme cytochrome subunit in the light-harvesting (LH1) complex-associated RC in close proximity to the low-potential heme-1 group. The binding interface between the two proteins is primarily formed by uncharged residues and is characterized by hydrophobic features. This co-crystal structure provides a model for the detailed study of long-range trans-protein electron tunneling pathways in biological systems.