The Hemophore HasA from Yersinia pestis (HasAyp) Coordinates Hemin with a Single Residue, Tyr75, and with Minimal Conformational Change

Hemophores from Serratia marcescens (HasAsm) and Pseudomonas aeruginosa (HasAp) bind hemin between two loops, which harbor the axial ligands H32 and Y75. Hemin binding to the Y75 loop triggers closing of the H32 loop and enables binding of H32. Because Yersinia pestis HasA (HasAyp) presents a Gln at position 32, we determined the structures of apo-and holo-HasAyp. Surprisingly, the Q32 loop in apo-HasAyp is already in the closed conformation but no residue from the Q32 loop binds hemin in holo-HasAyp. In agreement with the minimal reorganization between the apo-and holo-structures, the hemin on-rate is too fast to detect by conventional stopped-flow measurements

Light-Induced N₂O Production from a Non-Heme Iron–Nitrosyl Dimer

Two non-heme iron–nitrosyl species, [Fe₂(N-Et-HPTB)(O₂CPh)(NO)₂](BF4)₂(1a) and [Fe₂(N-Et-HPTB)(DMF)₂(NO)(OH)](BF₄)₃ (2a), are characterized by FTIR and resonance Raman spectroscopy. Binding of NO is reversible in both complexes, which are prone to NO photolysis under visible light illumination. Photoproduction of N₂O occurs in high yield for 1a but not 2a. Low-temperature FTIR photolysis experiments with 1a in acetonitrile do not reveal any intermediate species, but in THF at room temperature, a new {FeNO}⁷ species quickly forms under illumination and exhibits a ν(NO) vibration indicative of nitroxyl-like character. This metastable species reacts further under illumination to produce N₂O. A reaction mechanism is proposed, and implications for NO reduction in flavodiiron proteins are discussed.National Institutes of Health (U.S.) (GM074785)National Institutes of Health (U.S.) (GM032134

Replacing Arginine 33 for Alanine in the Hemophore HasA from Pseudomonas aeruginosa Causes Closure of the H32 Loop in the Apo-Protein

Previous characterization of hemophores from Serratia marcescens (HasAs), Pseudomonas aeruginosa (HasAp) and Yersinia pestis (HasAyp) showed that hemin binds between two loops, where it is axially coordinated by H32 and Y75. The Y75 loop is structurally conserved in all three hemophores and harbors conserved ligand Y75. The other loop contains H32 in HasAs and HasAp, but a noncoordinating Q32 in HasAyp. The H32 loop in apo-HasAs and apo-HasAp is in an open conformation, which places H32 about 30 Å from the hemin-binding site. Hence, hemin binding onto the Y75 loop of HasAs or HasAp triggers a large relocation of the H32 loop from an open- to a closed-loop conformation and enables coordination of the hemin-iron by H32. In comparison, the Q32 loop in apo-HasAyp is in the closed conformation and hemin binding occurs with minimal reorganization and without coordinative interactions with the Q32 loop. Studies in crystallo and in solution have established that the open H32 loop in apo-HasAp and apo-HasAs is well structured and minimally affected by conformational dynamics. In this study we address the intriguing issue of the stability of the H32 loop in apo-HasAp and how hemin binding triggers its relocation. We address this question with a combination of NMR spectroscopy, X-ray crystallography, and molecular dynamics simulations and find that R33 is critical to the stability of the open H32 loop. Replacing R33 with A causes the H32 loop in R33A apo-HasAp to adopt a conformation similar to that of holo-HasAp. Finally, stopped-flow absorption and resonance Raman analyses of hemin binding to apo-R33A HasAp indicates that the closed H32 loop slows down the insertion of the heme inside the binding pocket, presumably as it obstructs access to the hydrophobic platform on the Y75 loop, but accelerate the completion of the heme iron coordination

Comparative proteomic analysis of glomerular proteins in primary and bucillamine-induced membranous nephropathy

BackgroundAnti-phospholipase A2 receptor autoantibody (PLA2R Ab)-associated membranous nephropathy (MN) is the most common form of primary MN (pMN). On the other hand, bucillamine (BCL), an antirheumatic drug developed in Japan, was reported to cause a rare form of secondary MN (sMN). Between these MN forms, comparative proteomic analysis of glomerular proteins has not been performed.MethodsWe used renal biopsy specimens from 6 patients with PLA2R Ab (+) pMN, 6 patients with PLA2R Ab (‒) pMN, 6 patients with BCL-induced sMN, and 5 control cases (time 0 transplant biopsies). Proteins were extracted from laser-microdissected glomeruli and analyzed using mass spectrometry. The quantification values of protein abundance in each MN group were compared with those in the control group.ResultsMore than 800 proteins with high confidence were identified. Principal component analysis revealed a different distribution between the pMN and sMN groups. For further analysis, 441 proteins matched with ≥ 3 peptides were selected. Among the pMN and sMN groups, we compared the profiles of several protein groups based on the structural and functional characteristics, such as immunoglobulins, complements, complement-regulating proteins, podocyte-associated proteins, glomerular basement membrane proteins, and several proteins that are known to be associated with kidney diseases, including MN. In all MN groups, increased levels of immunoglobulins (IgG, IgA, and IgM), complements (C3, C4, and C9), complement factor H-related protein 5, type XVIII collagen, calmodulin, polyubiquitin, and ubiquitin ligase were observed. For some proteins, such as type VII collagen and nestin, the fold-change values were significantly different between the pMN and sMN groups.ConclusionsBetween the pMN and BCL-induced sMN groups, we observed common and different alterations in protein levels such as known disease-associated proteins and potential disease marker proteins

Stent-Related Adverse Events as Related to Dual Antiplatelet Therapy in First- vs Second-Generation Drug-Eluting Stents

[Background] There are limited data on the long-term stent-related adverse events as related to the duration of dual antiplatelet therapy (DAPT) in second-generation (G2) drug-eluting stents (DES) compared with first-generation (G1) DES. [Objectives] This study sought to compare the long-term stent-related outcomes of G2-DES with those of G1-DES. [Methods] The study group consisted of 15, 009 patients who underwent their first coronary revascularization with DES from the CREDO-Kyoto PCI/CABG (Coronary Revascularization Demonstrating Outcome Study in Kyoto Percutaneous Coronary Intervention/Coronary Artery Bypass Grafting) Registry Cohort-2 (first-generation drug-eluting stent [G1-DES] period; n = 5, 382) and Cohort-3 (second-generation drug eluting stent [G2-DES] period; n = 9, 627). The primary outcome measures were definite stent thrombosis (ST) and target vessel revascularization (TVR). [Results] The cumulative 5-year incidences of definite ST and TVR were significantly lower in the G2-DES group than in the G1-DES group (0.7% vs 1.4%; P < 0.001; and 16.2% vs 22.1%; P < 0.001, respectively). The lower adjusted risk of G2-DES relative to G1-DES for definite ST and TVR remained significant (HR: 0.53; 95% CI: 0.37-0.76; P < 0.001; and HR: 0.74; 95% CI: 0.68-0.81; P < 0.001, respectively). In the landmark analysis that was based on the DAPT status at 1 year, the lower adjusted risk of on-DAPT status relative to off-DAPT was significant for definite ST beyond 1 year in the G1-DES stratum (HR: 0.42; 95% CI: 0.24-0.76; P = 0.004) but not in the G2-DES stratum (HR: 0.66; 95% CI: 0.26-1.68; P = 0.38) (Pinteraction = 0.14). [Conclusions] G2-DES compared with G1-DES were associated with a significantly lower risk for stent-related adverse events, including definite ST and TVR. DAPT beyond 1 year was associated with a significantly lower risk for very late ST of G1-DES but not for that of G2-DES

Direct Electrochemistry of Phanerochaete chrysosporium Cellobiose Dehydrogenase Covalently Attached onto Gold Nanoparticle Modified Solid Gold Electrodes.

Achieving efficient electrochemical communication between redox enzymes and various electrode materials is one of the main challenges in bioelectrochemistry and is of great importance for developing electronic applications. Cellobiose dehydrogenase (CDH) is an extracellular flavocytochrome composed of a catalytic FAD containing dehydrogenase domain (DH(CDH)), a heme b containing cytochrome domain (CYT(CDH)), and a flexible linker region connecting the two domains. Efficient direct electron transfer (DET) of CDH from the basidiomycete Phanerochaete chrysosporium (PcCDH) covalently attached to mixed self-assembled monolayer (SAM) modified gold nanoparticle (AuNP) electrode is presented. The thiols used were as follows: 4-aminothiophenol (4-ATP), 4-mercaptobenzoic acid (4-MBA), 4-mercaptophenol (4-MP), 11-mercapto-1-undecanamine (MUNH(2)), 11-mercapto-1-undecanoic acid (MUCOOH), and 11-mercapto-1-undecanol (MUOH). A covalent linkage between PcCDH and 4-ATP or MUNH(2) in the mixed SAMs was formed using glutaraldehyde as cross-linker. The covalent immobilization and the surface coverage of PcCDH were confirmed with surface plasmon resonance (SPR). To improve current density, AuNPs were cast on the top of polycrystalline gold electrodes. For all the immobilized PcCDH modified AuNPs electrodes, cyclic voltammetry exhibited clear electrochemical responses of the CYT(CDH) with fast electron transfer (ET) rates in the absence of substrate (lactose), and the formal potential was evaluated to be +162 mV vs NHE at pH 4.50. The standard ET rate constant (k(s)) was estimated for the first time for CDH and was found to be 52.1, 59.8, 112, and 154 s(-1) for 4-ATP/4-MBA, 4-ATP/4-MP, MUNH(2)/MUCOOH, and MUNH(2)/MUOH modified electrodes, respectively. At all the mixed SAM modified AuNP electrodes, PcCDH showed DET only via the CYT(CDH). No DET communication between the DH(CDH) domain and the electrode was found. The current density for lactose oxidation was remarkably increased by introduction of the AuNPs. The 4-ATP/4-MBA modified AuNPs exhibited a current density up to 30 μA cm(-2), which is ∼70 times higher than that obtained for a 4-ATP/4-MBA modified polycrystalline gold electrode. The results provide insight into fundamental electrochemical properties of CDH covalently immobilized on gold electrodes and promote further applications of CDHs for biosensors, biofuel cells, and bioelectrocatalysis

Adult granulosa cell tumors of the ovary: A retrospective study of 30 cases with respect to the expression of steroid synthesis enzymes

Objective: Some, but not all, granulosa cell tumors are characterized by estrogen production. This study was designed to determine whether there are clinical or pathological variations in granulosa cell tumors in relation to the expression of sex steroid synthesis enzymes. Methods: Clinical symptoms, serum hormonal values, and histology of 30 granulosa cell tumor patients who underwent surgery between 2002 and 2014 were retrospectively reviewed. Results: Most patients presented with abnormal genital bleeding including abnormal menstrual cycles. Eight of 16 patients older than 50 years had endometrial hyperplasia and one had endometrial cancer. Serum 17β-estradiol (E2) levels tended to be higher in patients over 50 years of age (p=0.081). Serum follicle-stimulating hormone (FSH) levels were low in all patients irrespective of serum E2 levels. Magnetic resonance imaging revealed a thicker endometrium in older as compared to younger patients (p<0.05). Tumor cells in the majority of cases were positive for inhibin α and P450 aromatase, irrespective of age and serum E2 levels. P450 17α-hydroxylase (P450c17) expression varied among cases. P450c17 was strongly positive in luteinized tumor cells and weakly positive in theca cells and fibroblasts. High E2 levels were associated with P450c17-positive cells in the tumor (p<0.05). Conclusion: The expression of hormone-synthesizing enzymes divides granulosa cell tumors into 2 distinct types; tumors with P450c17-positive cells show elevated serum E2 and related clinical symptoms, while tumors without these cells show symptoms related to FSH suppression by inhibin