P. aeruginosa CtpA protease adopts a novel activation mechanism to initiate the proteolytic process.

During bacterial cell growth, hydrolases cleave peptide cross-links between strands of the peptidoglycan sacculus to allow new strand insertion. The Pseudomonas aeruginosa carboxyl-terminal processing protease (CTP) CtpA regulates some of these hydrolases by degrading them. CtpA assembles as an inactive hexamer composed of a trimer-of-dimers, but its lipoprotein binding partner LbcA activates CtpA by an unknown mechanism. Here, we report the cryo-EM structures of the CtpA-LbcA complex. LbcA has an N-terminal adaptor domain that binds to CtpA, and a C-terminal superhelical tetratricopeptide repeat domain. One LbcA molecule attaches to each of the three vertices of a CtpA hexamer. LbcA triggers relocation of the CtpA PDZ domain, remodeling of the substrate binding pocket, and realignment of the catalytic residues. Surprisingly, only one CtpA molecule in a CtpA dimer is activated upon LbcA binding. Also, a long loop from one CtpA dimer inserts into a neighboring dimer to facilitate the proteolytic activity. This work has revealed an activation mechanism for a bacterial CTP that is strikingly different from other CTPs that have been characterized structurally.

Ηigh-resolution structure of mammalian PI31-20S proteasome complex reveals mechanism of proteasome inhibition.

Proteasome-catalyzed protein degradation mediates and regulates critical aspects of many cellular functions and is an important element of proteostasis in health and disease. Proteasome function is determined in part by the types of proteasome holoenzymes formed between the 20S core particle that catalyzes peptide bond hydrolysis and any of multiple regulatory proteins to which it binds. One of these regulators, PI31, was previously identified as an in vitro 20S proteasome inhibitor, but neither the molecular mechanism nor the possible physiologic significance of PI31-mediated proteasome inhibition has been clear. Here we report a high-resolution cryo-EM structure of the mammalian 20S proteasome in complex with PI31. The structure shows that two copies of the intrinsically disordered carboxyl terminus of PI31 are present in the central cavity of the closed-gate conformation of the proteasome and interact with proteasome catalytic sites in a manner that blocks proteolysis of substrates but resists their own degradation. The two inhibitory polypeptide chains appear to originate from PI31 monomers that enter the catalytic chamber from opposite ends of the 20S cylinder. We present evidence that PI31 can inhibit proteasome activity in mammalian cells and may serve regulatory functions for the control of cellular proteostasis.

Identification, expression profiles, and binding properties of chemosensory protein 18 in Plutella xylostella (Lepidoptera: Plutellidae).

Chemosensory proteins (CSPs) are highly efficient carry tools to bind and deliver hydrophobic compounds, which play an important role in the chemosensory process in insects. The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is a cosmopolitan pest that attacks cruciferous crops. However, the detailed physiological functions of CSPs in P. xylostella remain limited to date. Here, we identified a typical CSP, named PxylCSP18, in P. xylostella and investigated its expression patterns and binding properties of volatiles. PxylCSP18 was highly expressed in antennae and head (without antennae), and the expression level in the male antennae of P. xylostella was obviously higher than that in the female antennae. Moreover, PxylCSP18 has a relatively broad binding spectrum. Fluorescence competitive binding assays showed that PxylCSP18 had strong binding abilities with 14 plant volatiles (Ki < 10 µM) that were repellent or attractive to P. xylostella. Notably, PxylCSP18 had no significant binding affinity to (Z)-11-hexadecenal, (Z)-11-hexadecenyl acetate, and (Z)-11-hexadecenyl alcolol, which are the pheromone components of P. xylostella. The attractive effects of trans-2-hexen-1-ol and isopropyl isothiocyanate to male adults and the attractive effects of isopropyl isothiocyanate and the repellent effects of linalool to female adults were significantly decreased after knocked down the expression of PxylCSP18. Our results revealed that PxylCSP18 might play an important role in host plant detection, avoidance of unsuitable hosts, and selection of oviposition sites; however, it does not participate in mating behavior. Overall, these results extended our knowledge on the CSP-related functions, which provided insightful information about CSP-targeted insecticides.

Immune Checkpoint Inhibitors Suppress Hepatitis C Virus Replication in Infected Patients With Solid Tumors.

INTRODUCTION: Data are scarce regarding the virologic impact and safety of immune checkpoint inhibitors (ICI) in patients with chronic hepatitis C virus (HCV) infection. We examined the virologic impact of ICI in HCV-infected patients with solid tumors and their safety. METHODS: HCV-infected patients with solid tumor treated with ICI at our institution between April 26, 2016, and January 5, 2022, were enrolled in a prospective observational study. The primary outcomes were ICI-induced changes in HCV viremia (HCV inhibition and HCV reactivation) and safety of ICI. RESULTS: We enrolled 52 consecutive patients with solid tumors treated with ICI. Most were men (41; 79%), White (31; 59%), without cirrhosis (34; 65%), and with HCV genotype 1 (40; 77%). Four patients (7.7%) experienced HCV inhibition while receiving ICI including 1 patient who developed undetectable viremia for 6 months in the absence of direct-acting antivirals (DAA). Two patients (4%) developed HCV reactivation, both while receiving immunosuppressive therapy for ICI-related toxic effects. Adverse events occurred in 36 patients (69%), and 39 of the 47 adverse events (83%) were grade 1-2. Grade 3-4 adverse events occurred in 8 patients (15%), and in all cases, they were related to ICI, not to HCV. No HCV-associated liver failure or death occurred. DISCUSSION: Inhibition of HCV replication with virologic cure can develop in patients receiving ICI without DAA. HCV reactivation occurs primarily in patients receiving immunosuppressants for ICI-related toxic effects. ICI are safe in HCV-infected patients with solid tumors. Chronic HCV infection should not be considered a contraindication for ICI therapy.

Ka-band beam-scanning leaky-wave antenna fed by reconfigurable spoof surface plasmon polaritons.

A leaky-wave antenna (LWA) based on reconfigurable spoof surface plasmon polaritons (SSPP) is proposed for beam scanning in the Ka band, which consists of a reconfigurable SSPP waveguide and a periodic array of metal rectangular split rings. Both numerical simulations and experimental measurements show that the reconfigurable SSPP-fed LWA has good performance in the frequency range from 25 to 30 GHz. Specifically, as the bias voltage changes from 0 to 15 V, we can achieve the maximum sweep range of 24° at a single frequency and 59° at multiple frequency points, respectively. Owing to the wide-angle beam-steering feature, as well as the field confinement and wavelength compression properties derived from the SSPP architecture, the proposed SSPP-fed LWA possesses great potential applications in the compact and miniaturized devices and systems of the Ka band.

Nitric oxide synthase is required for the pea aphid's defence against bacterial infection.

Compared to other insects, the pea aphid Acyrthosiphon pisum has a reduced immune system with an absence of genes coding for a lot of immunity-related molecules. Notably, nitric oxide synthase (NOS), which catalyses the synthesis of nitric oxide (NO), is present in the pea aphid. However, the role of NO in the immune system of pea aphid remains unclear. In this study, we explored the role of NO in the defence of the pea aphid against bacterial infections and found that the NOS gene of the pea aphid responded to an immune challenge, with the expression of ApNOS observably upregulated after bacterial infections. Knockdown of ApNOS using RNA interference or inhibition of NOS activity increased the number of live bacterial cells in aphids and the mortality of aphids after bacterial infection. Conversely, the increase in NO level in aphids using NO donor inhibited the bacterial growth, increased the survival of bacteria-infected aphids, and upregulated immune genes, such as Toll pathway and phagocytosis related genes. Thus, NO promotes immune responses and plays an important role in the immune system of pea aphid.

Efficiency comparison of an isoeugenol-derivated compound, eugenosedin-A, with glibenclamide and pioglitazone in protecting cardiovascular dysfunction of diabetic SHR.

This study was to investigate three agents possible protective effect against DM-induced cardiovascular dysfunction in spontaneously hypertensive rats (SHR). Control group was fed normal diet, DM group was injected with STZ/NA and fed high fat diet (HFD), and treatment groups were given STZ/NA, fed HFD, and then oral gavaged with eugenosedin-A (Eu-A), glibenclamide (Gli), or pioglitazone (Pio) 5 mg/kg/per day for 4-week, respectively. Eu-A, Gli, and Pio clearly ameliorated the changes of body weight, cardiac weight, and the biochemical parameters, cardiovascular disorders and inflammation. Like Gli and Pio, Eu-A may be effectively to control DM and the cardiovascular dysfunction.

Serpin-4 Negatively Regulates Prophenoloxidase Activation and Antimicrobial Peptide Synthesis in the Silkworm, Bombyx mori.

The prophenoloxidase (PPO) activation and Toll antimicrobial peptide synthesis pathways are two critical immune responses in the insect immune system. The activation of these pathways is mediated by the cascade of serine proteases, which is negatively regulated by serpins. In this study, we identified a typical serpin, BmSerpin-4, in silkworms, whose expression was dramatically up-regulated in the fat body and hemocytes after bacterial infections. The pre-injection of recombinant BmSerpin-4 remarkably decreased the antibacterial activity of the hemolymph and the expression of the antimicrobial peptides (AMPs) gloverin-3, cecropin-D, cecropin-E, and moricin in the fat body under Micrococcus luteus and Yersinia pseudotuberculosis serotype O: 3 (YP III) infection. Meanwhile, the inhibition of systemic melanization, PO activity, and PPO activation by BmSerpin-4 was also observed. Hemolymph proteinase 1 (HP1), serine protease 2 (SP2), HP6, and SP21 were predicted as the candidate target serine proteases for BmSerpin-4 through the analysis of residues adjacent to the scissile bond and comparisons of orthologous genes in Manduca sexta. This suggests that HP1, SP2, HP6, and SP21 might be essential in the activation of the serine protease cascade in both the Toll and PPO pathways in silkworms. Our study provided a comprehensive characterization of BmSerpin-4 and clues for the further dissection of silkworm PPO and Toll activation signaling.

The mycobacterial proteasomal ATPase Mpa forms a gapped ring to engage the 20S proteasome.

Although many bacterial species do not possess proteasome systems, the actinobacteria, including the human pathogen Mycobacterium tuberculosis, use proteasome systems for targeted protein removal. Previous structural analyses of the mycobacterial proteasome ATPase Mpa revealed a general structural conservation with the archaeal proteasome-activating nucleotidase and eukaryotic proteasomal Rpt1-6 ATPases, such as the N-terminal coiled-coil domain, oligosaccharide-/oligonucleotide-binding domain, and ATPase domain. However, Mpa has a unique ß-grasp domain that in the ADP-bound crystal structure appears to interfere with the docking to the 20S proteasome core particle (CP). Thus, it is unclear how Mpa binds to proteasome CPs. In this report, we show by cryo-EM that the Mpa hexamer in the presence of a degradation substrate and ATP forms a gapped ring, with two of its six ATPase domains being highly flexible. We found that the linkers between the oligonucleotide-binding and ATPase domains undergo conformational changes that are important for function, revealing a previously unappreciated role of the linker region in ATP hydrolysis-driven protein unfolding. We propose that this gapped ring configuration is an intermediate state that helps rearrange its ß-grasp domains and activating C termini to facilitate engagement with proteasome CPs. This work provides new insights into the crucial process of how an ATPase interacts with a bacterial proteasome protease.

Pre-germinated brown rice alleviates non-alcoholic fatty liver disease induced by high fructose and high fat intake in rat.

In past researches, we had been proved the action mechanism of pre-germinated brown rice (PGBR) to treat metabolic syndrome and diabetes mellitus. This study was to investigate the protective effect of PGBR in high fructose and high fat-induced non-alcoholic fatty liver disease (NAFLD) in rodents. WKY rats were divided into: Control group was fed normal drinking water and diet; FLD group was fed 10% high-fructose-water (HFW) and high-fat-diet (HFD); PGBR group was given HFW, and HFD mixed PGBR. After four weeks, the body, hepatic and cardiac weight gains of FLD group had significant increases than that of Control group. The enhanced blood pressure and heart rate, hypertriglyceridemia, hyperuricemia, and higher liver function index (GPT levels) were observed; meanwhile, the IL-6 and TNF-α levels of serum, and TG level of liver were also elevated in FLD group. The related protein expressions of lipid synthesis, inflammation, cardiac fibrosis, and hypertrophy were deteriorated by HFW/HFD. However, in treatment group, PGBR decreased all above influenced parameters, additionally GOT; and related protein expressions. PGBR treated HFW/HFD-induced NAFLD and cardiac complications might be via improving lipid homeostasis, and inhibiting inflammation. Together, PGBR could be used as a healthy food for controlling NAFLD and its' cardiac dysfunction.

Clinicopathologic Features, Treatment Response, and Outcomes of Immune Checkpoint Inhibitor-Related Esophagitis.

BACKGROUND: Although immune checkpoint inhibitors (ICIs) have provided practice-changing outcomes in treating many cancers, ICI-related gastrointestinal toxicity can limit their use. Upper gastrointestinal toxicity is not common nor as well described as lower gastrointestinal toxicity. We aimed to characterize the clinical presentation, endoscopic and histologic features, treatment response, and outcomes of ICI-related esophagitis. METHODS: We retrospectively studied patients at The University of Texas MD Anderson Cancer Center in whom esophagitis developed after receiving ICIs from June 2011 through January 2020. We included patients with endoscopic evidence of esophagitis and excluded those with other obvious causes of esophagitis. A chi-square test was used to assess associations between categorical variables. The Mann-Whitney U test was used to compare differences between continuous variables. RESULTS: Of 657 consecutive patients who underwent esophagogastroduodenoscopy (EGD) during or within 6 months of completing ICI-based therapy, 21 (3%) had esophagitis deemed to be from ICIs. Of these patients, 1 (5%) received an inhibitor of CTLA-4 alone, 15 (71%) received anti-PD-1 or PD-L1 monotherapy, and 5 (24%) received a combination of these. Median time from ICI initiation to onset of esophagitis was 4 months. Upon evaluation with EGD, only 3 patients (14%) had isolated esophageal involvement; 18 (86%) had concurrent involvement of the stomach, duodenum, or both. Most patients (67%) were treated with proton pump inhibitors, and 4 (19%) received steroids (prednisone or budesonide). The mortality rate was 38% (median follow-up, 15 months). CONCLUSIONS: Esophagitis associated with ICI use is rare. The diagnosis is one of exclusion because its clinical presentation appears similar to that of inflammation resulting from other causes. It often occurs in conjunction with other upper gastrointestinal toxicity. Symptoms are mild and respond well to nonimmunosuppressive treatment, with few severe complications.

Clinical Characteristics and Outcomes of Oral Mucositis Associated With Immune Checkpoint Inhibitors in Patients With Cancer.

BACKGROUND: Immune checkpoint inhibitor (ICI) therapy predisposes patients to immune-related adverse events (irAEs). Data are limited regarding the incidence, management, and outcomes of one such irAE: mucositis. In this study, we evaluated the clinical characteristics, disease course, treatment, and outcomes of ICI-mediated mucositis. METHODS: This was a retrospective, single-center study of patients who received ICI therapy and developed oral mucositis at The University of Texas MD Anderson Cancer Center from January 2009 to September 2019. Inclusion criteria included age ≥18 years, a diagnosis of oral mucositis and/or stomatitis based on ICD-9 and ICD-10 codes, and therapy using CTLA-4 or PD-1/L1 inhibitors alone or combined with other agents. RESULTS: We identified 152 patients with a mean age of 60 years, 51% of whom were men. Of the sample patients, 73% had stage IV cancer, with melanoma the most common (28%). Median time from ICI initiation to mucositis was 91 days. The most common clinical presentation of mucositis was odynophagia and/or oral pain (89%), 91% developed CTCAE grade 1-2 mucositis, and 78% received anti-PD-1/L1 monotherapy. Compared with anti-PD-1/L1-based therapy, anti-CTLA-4-based therapy was more frequently associated with earlier onset of mucositis (73 vs 96 days; P=.077) and a lower rate of symptom resolution (76% vs 92%; P=.029); 24% of patients required immunosuppressive therapy, which was associated with longer symptom duration (84 vs 34 days; P=.002) and higher mucositis recurrence rate (61% vs 32%; P=.006). ICI interruption was associated with worse survival (P=.037). Mucositis recurrence, immunosuppressant use, and presence of other irAEs did not affect survival. CONCLUSIONS: For ICI-mediated mucositis, a diagnosis of exclusion has not been well recognized and is understudied. Although the clinical symptoms of mucositis are mostly mild, approximately 25% of patients require immunosuppression. Mucositis recurrence can occur in approximately 39% patients. Our results showed that ICI interruption compromises overall survival.

Hepatobiliary and Pancreatic Adverse Events.

The expanded approval of immune checkpoint inhibitors (ICIs) for the treatment of multiple cancer types has offered patients more opportunities in treatment selection and survival.Hepatotoxicity is a well-recognized immune-related adverse event (irAE) associated with treatment with ICI. It is considered a type of drug-induced liver injury (DILI). Depending on the specific ICI and whether the patient receives single- or dual-drug therapy, the incidence of hepatotoxicity in general could be as high as 30%. As more patients receive treatment with ICI, more cases of hepatotoxicity are expected to occur. Clinicians must exercise close pharmacovigilance to recognize liver-related irAEs early.ICI-mediated hepatobiliary toxicity (or "IMH") generally presents as asymptomatic elevations of alanine transaminase and aspartate transaminase, with or without alkaline phosphatase elevation. Some patients may present with jaundice, fever, or malaise. Rarely, it may cause liver failure and death. The diagnosis of IMH is made after careful exclusion of other causes of acute hepatitis based on medical history, laboratory evaluation, imaging, and liver histological findings. In clinically significant cases of IMH, the management involves discontinuation of ICI followed by close monitoring and the initiation of immunosuppression. Current society guidelines, which are not based on robust evidence, specify treatment recommendations depending on the grade of liver injury, according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. However, our clinical experience suggests possible alternatives, including lower corticosteroid dosing with adjunct therapies. Whereas current guidelines endorse permanent cessation of future ICI treatment in patients diagnosed with grades 3-4 IMH, published clinical experience suggests potential for flexibility when assessing for candidacy of resuming ICI.Because histologic bile duct injury has been observed in cases ascribed to IMH, ICI-mediated cholangiopathic disease probably exists on a spectrum within IMH. Even extrahepatic bile duct involvement has been observed. This phenotype warrants special considerations in treatment and surveillance.ICI-related cholecystitis has been rarely reported in the literature. Management follows current standards of care for typical cases of cholecystitis. No relationship with ICI-mediated cholangiopathic disease has been observed.Assessing for and managing ICI-associated pancreatic injury remain challenging to the clinician. Many cases of asymptomatic serum lipase elevation are detected on routine labs without clinical signs or symptoms of typical acute pancreatitis. However, symptomatic patients should be initially managed like traditional cases of acute pancreatitis requiring hospitalization for evaluation and inpatient management.

Structural basis for allosteric stimulation of Sir2 activity by Sir4 binding.

The budding yeast Sir2 (silent information regulator 2) protein is the founding member of the sirtuin family of NAD-dependent histone/protein deacetylases. Its function in transcriptional silencing requires both the highly conserved catalytic domain and a poorly understood N-terminal regulatory domain (Sir2N). We determined the structure of Sir2 in complex with a fragment of Sir4, a component of the transcriptional silencing complex in Saccharomyces cerevisiae. The structure shows that Sir4 is anchored to Sir2N and contacts the interface between the Sir2N and the catalytic domains through a long loop. We discovered that the interaction between the Sir4 loop and the interdomain interface in Sir2 is critical for allosteric stimulation of the deacetylase activity of Sir2. These results bring to light the structure and function of the regulatory domain of Sir2, and the knowledge should be useful for understanding allosteric regulation of sirtuins in general.

Association of Chronic Immune-Mediated Diarrhea and Colitis With Favorable Cancer Response.

BACKGROUND: Immune-mediated diarrhea and colitis (IMDC) is a common immune-related adverse effect related to immune checkpoint inhibitors. We aimed to identify risk factors for chronic IMDC and its prognostic value in cancer outcomes. METHODS: We retrospectively collected data on patients with a diagnosis of IMDC between January 2018 and October 2019 and grouped them based on disease duration into acute (≤3 months) and chronic (>3 months) categories. A logistic regression model and the Kaplan-Meier method with log-rank tests were used for biostatistical analysis. RESULTS: In our sample of 88 patients, 43 were in the chronic group and 45 were in the acute group. Genitourinary cancer and melanoma accounted for 70% of malignancies. PD-1/L1 monotherapy (52%) was the more frequently used regimen. We showed that chronic IMDC was associated with proton pump inhibitor use (odds ratio [OR], 3.96; P=.026), long duration of IMDC symptoms (OR, 1.05; P<.001) and hospitalization (OR, 1.07; P=.043), a histologic feature of chronic active colitis (OR, 4.8; P=.025) or microscopic colitis (OR, 5.0; P=.045), and delayed introduction of selective immunosuppressive therapy (infliximab/vedolizumab; OR, 1.06; P=.047). Chronic IMDC also reflected a better cancer response to immune checkpoint inhibitors (30% vs 51%; P=.002) and was accompanied by improved overall survival (P=.035). Similarly, higher doses of selective immunosuppressive therapy were associated with better overall survival (P=.018). CONCLUSIONS: Chronic IMDC can develop among patients with a more aggressive disease course and chronic features on colon histology. It likely reflects a prolonged immune checkpoint inhibitor effect and is associated with better cancer outcome and overall survival.

Expression Profiles and Binding Properties of the Chemosensory Protein PxylCSP11 from the Diamondback Moth, Plutella xylostella (Lepidoptera: Plutellidae).

The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) is one of the most destructive pests to cruciferous plants worldwide. The oligophagous moth primarily utilizes its host volatiles for foraging and oviposition. Chemosensory proteins (CSPs) are soluble carrier proteins with low molecular weight, which recognize and transport various semiochemicals in insect chemoreception. At present, there is limited information on the recognition of host volatiles by CSPs of P. xylostella. Here, we investigated expression patterns and binding characteristics of PxylCSP11 in P. xylostella. The open reading frame of PxylCSP11 was 369-bp encoding 122 amino acids. PxylCSP11 possessed four conserved cysteines, which was consistent with the typical characteristic of CSPs. PxylCSP11 was highly expressed in antennae, and the expression level of PxylCSP11 in male antennae was higher than that in female antennae. Fluorescence competitive binding assays showed that PxylCSP11 had strong binding abilities to several ligands, including volatiles of cruciferous plants, and (Z)-11-hexadecenyl acetate (Z11-16:Ac), a major sex pheromone of P. xylostella. Our results suggest that PxylCSP11 may play an important role in host recognition and spouse location in P. xylostella.

Identification of Fatty Acid Binding Protein 5 Inhibitors Through Similarity-Based Screening.

Fatty acid binding protein 5 (FABP5) is a promising target for development of inhibitors to help control pain and inflammation. In this work, computer-based docking (DOCK6 program) was employed to screen ∼2 M commercially available compounds to FABP5 based on an X-ray structure complexed with the small molecule inhibitor SBFI-26 previously identified by our group (also through virtual screening). The goal was discovery of additional chemotypes. The screen resulted in the purchase of 78 candidates, which led to the identification of a new inhibitor scaffold (STK-0) with micromolar affinity and apparent selectivity for FABP5 over FABP3. A second similarity-based screen resulted in three additional hits (STK-15, STK-21, STK-22) from which preliminary SAR could be derived. Notably, STK-15 showed comparable activity to the SBFI-26 reference under the same assay conditions (1.40 vs 0.86 µM). Additional molecular dynamics simulations, free energy calculations, and structural analysis (starting from DOCK-generated poses) revealed that R enantiomers (dihydropyrrole scaffold) of STK-15 and STK-22 have a more optimal composition of functional groups to facilitate additional H-bonds with Arg109 of FABP5. This observation suggests enantiomerically pure compounds could show enhanced activity. Overall, our study highlights the utility of using similarity-based screening methods to discover new inhibitor chemotypes, and the identified FABP5 hits provide a strong starting point for future efforts geared to improve activity.

Structural Basis for the Species-Selective Binding of N,C-Capped Dipeptides to the Mycobacterium tuberculosis Proteasome.

The Mycobacterium tuberculosis (Mtb) 20S proteasome is vital for the pathogen to survive under nitrosative stress in vitro and to persist in mice. To qualify for drug development, inhibitors targeting Mtb 20S must spare both the human constitutive proteasome (c-20S) and immunoproteasome (i-20S). We recently reported members of a family of noncovalently binding dipeptide proteasome inhibitors that are highly potent and selective for Mtb 20S over human c-20S and i-20S. To understand the structural basis of their potency and selectivity, we have studied the structure-activity relationship of six derivatives and solved their cocrystal structures with Mtb 20S. The dipeptide inhibitors form an antiparallel ß-strand with the active site ß-strands. Selectivity is conferred by several features of Mtb 20S relative to its mouse counterparts, including a larger S1 pocket, additional hydrogen bonds in the S3 pocket, and hydrophobic interactions in the S4 pocket. Serine-20 and glutamine-22 of Mtb 20S interact with the dipeptides and confer Mtb-specific inhibition over c-20S and i-20S. The Mtb 20S and mammalian i-20S have a serine-27 that interacts strongly with the dipeptides, potentially explaining the higher inhibitory activity of the dipeptides toward i-20S over c-20S. This detailed structural knowledge will aid in optimizing the dipeptides as anti-tuberculosis drugs.

The Antinociceptive Agent SBFI-26 Binds to Anandamide Transporters FABP5 and FABP7 at Two Different Sites.

Human FABP5 and FABP7 are intracellular endocannabinoid transporters. SBFI-26 is an α-truxillic acid 1-naphthyl monoester that competitively inhibits the activities of FABP5 and FABP7 and produces antinociceptive and anti-inflammatory effects in mice. The synthesis of SBFI-26 yields several stereoisomers, and it is not known how the inhibitor binds the transporters. Here we report co-crystal structures of SBFI-26 in complex with human FABP5 and FABP7 at 2.2 and 1.9 Å resolution, respectively. We found that only (S)-SBFI-26 was present in the crystal structures. The inhibitor largely mimics the fatty acid binding pattern, but it also has several unique interactions. Notably, the FABP7 complex corroborates key aspects of the ligand binding pose at the canonical site previously predicted by virtual screening. In FABP5, SBFI-26 was unexpectedly found to bind at the substrate entry portal region in addition to binding at the canonical ligand-binding pocket. Our structural and binding energy analyses indicate that both R and S forms appear to bind the transporter equally well. We suggest that the S enantiomer observed in the crystal structures may be a result of the crystallization process selectively incorporating the (S)-SBFI-26-FABP complexes into the growing lattice, or that the S enantiomer may bind to the portal site more rapidly than to the canonical site, leading to an increased local concentration of the S enantiomer for binding to the canonical site. Our work reveals two binding poses of SBFI-26 in its target transporters. This knowledge will guide the development of more potent FABP inhibitors based upon the SBFI-26 scaffold.

Effects of pre-germinated brown rice treatment high-fat diet-induced metabolic syndrome in C57BL/6J mice.

To investigate using pre-germinated brown rice (PGBR) to treat metabolic syndrome, we fed one group of mice standard-regular-diet (SRD) for 20 weeks and another group of mice high-fat-diet (HFD) for 16 weeks. We subdivided them into HFD group and HFD + PGBR group whose dietary carbohydrate was replaced with PGBR for 4 weeks. The HFD group gained more weight, had higher blood pressure, heart rate, blood glucose and lipids, liver levels of TG, feces TG and bile acid, lower adipose levels of adipocytokine, lower skeletal muscle IR, IRS-1, IRS-2, PI3 K, Akt/PKB, GLUT-1, GLUT-4, GCK and PPAR-γ; higher liver SREBP-1, SCD-1, FAS, HMGCR, LDLR, CYP7α1 and PPAR-α, and higher adipose SREBP-1, SCD-1, FAS, and lower adipose PPAR-α and adiponectin. The HFD + PGBR group had clearly improved blood pressure, biochemical parameters and above proteins expressions. PGBR successful treatment of metabolic syndrome was achieved through improvements in glucose and lipid synthesis and metabolism.