Crystal Structures of the Tetratricopeptide Repeat Domains of Kinesin Light Chains: Insight into Cargo Recognition Mechanisms

Kinesin-1 transports various cargos along the axon by interacting with the cargos through its light chain subunit. Kinesin light chains (KLC) utilize its tetratricopeptide repeat (TPR) domain to interact with over 10 different cargos. Despite a high sequence identity between their TPR domains (87%), KLC1 and KLC2 isoforms exhibit differential binding properties towards some cargos. We determined the structures of human KLC1 and KLC2 tetratricopeptide repeat (TPR) domains using X-ray crystallography and investigated the different mechanisms by which KLCs interact with their cargos. Using isothermal titration calorimetry, we attributed the specific interaction between KLC1 and JNK-interacting protein 1 (JIP1) cargo to residue N343 in the fourth TRP repeat. Structurally, the N343 residue is adjacent to other asparagines and lysines, creating a positively charged polar patch within the groove of the TPR domain. Whereas, KLC2 with the corresponding residue S328 did not interact with JIP1. Based on these finding, we propose that N343 of KLC1 can form “a carboxylate clamp” with its neighboring asparagine to interact with JIP1, similar to that of HSP70/HSP90 organizing protein-1's (HOP1) interaction with heat shock proteins. For the binding of cargos shared by KLC1 and KLC2, we propose a different site located within the groove but not involving N343. We further propose a third binding site on KLC1 which involves a stretch of polar residues along the inter-TPR loops that may form a network of hydrogen bonds to JIP3 and JIP4. Together, these results provide structural insights into possible mechanisms of interaction between KLC TPR domains and various cargo proteins

Cactus: chemical, nutraceutical composition and potential bio-pharmacological properties

Cactus species are plants that grow in the arid and semiarid regions of the world. They have long fascinated the attention of the scientific community due to their unusual biology. Cactus species are used for a variety of purposes, such as food, fodder, ornamental, and as medicinal plants. In the last regard, they have been used in traditional medicine for eras by the ancient people to cure several diseases. Recent scientific investigations suggest that cactus materials may be used as a source of naturally-occurring products, such as mucilage, fiber, pigments, and antioxidants. For this reason, numerous species under this family are becoming endangered and extinct. This review provides an overview of the habitat, classification, phytochemistry, chemical constituents, extraction and isolation of bioactive compounds, nutritional and pharmacological potential with pre-clinical and clinical studies of different Cactus species. Furthermore, conservation strategies for the ornamental and endangered species have also been discussed.National Research Foundation of KoreaNational Research Foundation of Korea [2020R1G1A1004667]UMNG [IMP-CIAS-2942]FCT Portuguese Foundation for Science and Technology European Commission [DL 57/2016/CP1361/CT0022]FCT -Foundation for Science and TechnologyPortuguese Foundation for Science and Technology [UIDB/05183/2020]Dongguk University, Republic of KoreaINTERREG -MD.NET: When Brand Meets Peopleinfo:eu-repo/semantics/publishedVersio

Clinical effect of surgical correction for nasal pathology on the treatment of obstructive sleep apnea syndrome.

OBJECTIVES: This study aimed to evaluate the hypothesis that relief of nasal obstruction in subjects with obstructive sleep apnea (OSA) would lead to reduce OSA severity and to discuss the available evidence on the clinical efficacy of nasal surgery as a treatment modality for OSA. STUDY DESIGN: Twenty-five subjects who had reduced patency of nasal cavity and narrowing of retroglossal or retropalatal airways were diagnosed with OSA and underwent nasal surgery, such as septoplasty or turbinoplasty to correct nasal pathologies. The effect of the surgery on nasal patency was quantified by measuring minimal cross-sectional area (MCA) using acoustic rhinometry. The watch-PAT-derived respiratory disturbance index (RDI), apnea and hypopnea index (AHI), lowest oxygen saturation, and valid sleep time were measured before and after nasal surgery. RESULTS: The present study shows that the AHI and RDI decreased significantly and the lowest oxygen saturation and valid sleep time rose after nasal surgery in 25 OSA subjects. In addition, a reduction in subjective symptoms was observed in subjects and mean MCA increased after nasal surgery. Fourteen subjects were classified as responders and 11 subjects as non-responders. Responders showed considerable improvement of their subjective symptoms and the AHI and RDI were significantly lower after surgery. We found that the changes between pre- and post-operative AHI and RDI values were minimal in 11 non-responders. However, daytime somnolence and REM sleep time improved after nasal surgery in non-responders. CONCLUSIONS: Our study provides evidence that the surgical treatment of nasal pathology improves nasal airway patency and reduces OSA severity in 56% subjects. Furthermore, correction of nasal pathology appears to result in improved sleep quality in both responder and non-responders OSA subjects

The different mechanisms of insulin sensitizers to prevent type 2 diabetes in OLETF rats

OBJECTIVE: To investigate the effects of pioglitazone and metformin treatment during pre-diabetic period for the prevention of diabetes in a rat model. METHODS: OLETF rats aged 18-weeks, were treated with pioglitazone (10 mg/kg/day) and metformin (300 mg/kg/day) for 10 weeks from their pre-diabetic period. We measured weight, lipid profiles, fat distribution, glucose tolerance, and pancreatic insulin content. RESULTS: Prominent weight gain (mostly subcutaneous fat area) was observed in the pioglitazone-treated OLETF (O-P) rats versus significant weight loss was observed in the metformin-treated OLETF (O-M) rats. Pioglitazone reversed the serum triglyceride (TG) and FFAs levels to normal (TG 0.46 +/- 0.04 vs 0.88 +/- 0.05 mmol/l in LETO). At the age of 28 weeks, the O-P rats showed completely normal glucose tolerance, and the glucose disposal rate (GDR) was markedly improved (25.6 +/- 0.4 vs 20.6 +/- 0.5 mg/min/kg in O-C, p < 0.05). The O-M rats also showed an improved fasting glucose and GDR level, but not as much as those with O-P rats. The pancreas insulin contents were much improved in the O-P rats (22.9 +/- 1.2 vs 18.8 +/- 1.3 nmol/pancreas in O-M rats, p < 0.05) with histological improvement. CONCLUSION: The pre-diabetic treatment with pioglitazone, despite significant weight gain, completely prevents to develop diabetes and enhances beta cell function with preservation of islet cell changes. Metformin treatment was also effective, but mainly by ameliorating the insulin resistance with marked reduction in body weight. The reversal of dyslipidaemia and the fat redistribution might contribute to the greater improvement of pioglitazone treatment compared to metformin in OLETF rats

Binding experiments of the KLC1-TPR mutants with ALC1 peptide and protein.

<p>Isothermal titration calorimetry measurements of (A) KLC1-N343S mutant with the ALC1 peptide, (B) KLC1-N301A mutant with the ALC1 peptide, (C) KLC1-TPR with the cytosolic domain of ALC1 protein.</p

Comparison of ALC1- and JIP1- binding polar patches of KLC1-TPR.

<p>The distance between N301–N344 clamps of the ALC1-binding polar patch (marine) is 5.7 Å, while the N343-N386 clamp of the JIP1-binding polar patch (yellow) is closer at 3.6 Å. A lysine (orange) is present in the JIP1-binding polar patch compared to an alanine (cyan) of ALC1-binding polar patch.</p

Data collection and refinement statistics of KLC1-TPR and KLC2-TPR.

a<p>R_sym = Σ|I-<i>|/ΣI.</i></p><i>b<p>R_work = Σ||F₀|-|F_c||/Σ|F₀|, where F₀ and F_c are the observed and calculated structure factors, respectively. R_free was calculated as R_work using 4.6% and 5.1% of the data selected for KLC1-TPR and KLC2-TPR respectively.</p></i

Binding experiments of the KLC1 and KLC2 TPR domains with the JIP1 peptide.

<p>Isothermal titration calorimetry measurements of (A) KLC1-TPR with the JIP1 peptide, (B) KLC2-TPR with the JIP1 peptide, (C) KLC1-N343S mutant with the JIP1 peptide.</p