Identification and Biochemical Characterization of Major ß-Mannanase in Talaromyces cellulolyticus Mannanolytic System.

Talaromyces cellulolyticus is a promising fungus for providing a cellulase preparation suitable for the hydrolysis of lignocellulosic material, although its mannan-degrading activities are insufficient. In the present study, three core mannanolytic enzymes, including glycosyl hydrolase family 5-7 (GH5-7) ß-mannanase (Man5A), GH27 α-galactosidase, and GH2 ß-mannosidase, were purified from a culture supernatant of T. cellulolyticus grown with glucomannan, and the corresponding genes were identified based on their genomic sequences. Transcriptional analysis revealed that these genes were specifically induced by glucomannan. Two types of Man5A products, Man5A1 and Man5A2, were found as major proteins in the mannanolytic system. Man5A1 was devoid of a family 1 carbohydrate-binding module (CBM1) at the N-terminus, whereas Man5A2 was devoid of both CBM1 and Ser/Thr-rich linker region. The physicochemical and catalytic properties of both Man5A1 and Man5A2 were identical to those of recombinant Man5A (rMan5A) possessing CBM1, except for the cellulose-binding ability. Man5A CBM1 had little effect on mannan hydrolysis of pretreated Hinoki cypress. The results suggest that an improvement in Man5A CBM1 along with the augmentation of identified mannanolytic enzyme components would aid in efficient hydrolysis of softwood using T. cellulolyticus cellulase preparation.

Construction of thermostable cellobiohydrolase I from the fungus Talaromyces cellulolyticus by protein engineering.

Fungus-derived GH-7 family cellobiohydrolase I (CBHI, EC 3.2.1.91) is one of the most important industrial enzymes for cellulosic biomass saccharification. Talaromyces cellulolyticus is well known as a mesophilic fungus producing a high amount of CBHI. Thermostability enhances the economic value of enzymes by making them more robust. However, CBHI has proven difficult to engineer, a fact that stems in part from its low expression in heterozygous hosts and its complex structure. Here, we report the successful improvement of the thermostability of CBHI from T. cellulolyticus using our homologous expression system and protein engineering method. We examined the key structures that seem to contribute to its thermostability using the 3D structural information of CBHI. Some parts of the structure of the Talaromyces emersonii CBHI were grafted into T. cellulolyticus CBHI and thermostable mutant CBHIs were constructed. The thermostability was primarily because of the improvement in the loop structures, and the positive effects of the mutations for thermostability were additive. By combing the mutations, the constructed thermophilic CBHI exhibits high hydrolytic activity toward crystalline cellulose with an optimum temperature at over 70°C. In addition, the strategy can be applied to the construction of the other thermostable CBHIs.

Comparison of sedation between the endoscopy room and operation room during endoscopic submucosal dissection for neoplasms in the upper gastrointestinal tract.

BACKGROUND: The present study was performed to compare the safety of sedation during endoscopic submucosal dissection (ESD) in the endoscopy room versus operation room. METHODS: In total, 297 patients with gastrointestinal tumors who underwent ESD from January 2011 to December 2016 were retrospectively reviewed. The patients were divided into two groups: those who underwent ESD in the endoscopy room without propofol (Group E) versus operation room with propofol (Group O). The patient, tumor, and procedure characteristics; adverse events; and treatment outcomes were compared between the two groups. RESULTS: The patient and tumor characteristics, including age (73.6 ± 8.2 vs. 72.5 ± 9.1 years), comorbidities, and tumor size and histology, were not different between Groups E and O. The ESD procedure time was comparable between Groups E and O (105.4 ± 70.4 vs. 106.5 ± 64.4 min), and the anesthesia time was equivalent (138.3 ± 78.1 vs. 148.4 ± 68.8 min). There were no significant differences in adverse events between the two groups. During the ESD procedure, desaturation occurred significantly more often in Group E than O (12.9% vs. 4.0%, P = 0.021, odds ratio: 3.53, 95% CI: 1.17-14.4). The recovery time after ESD was significantly longer in Group E than O (180 (100-360) vs. 90 (0-180) min, P < 0.001). CONCLUSIONS: A decreased desaturation rate and shorter recovery time after ESD were the advantages of sedation in the operation room with propofol compared with sedation in the endoscopy room. These findings warrant further exploration of the advantages of safe and effective ESD for upper gastrointestinal neoplasms in the operation room.

Genetic improvement of xylose metabolism by enhancing the expression of pentose phosphate pathway genes in Saccharomyces cerevisiae IR-2 for high-temperature ethanol production.

The pentose phosphate pathway (PPP) plays an important role in the efficiency of xylose fermentation during cellulosic ethanol production. In simultaneous saccharification and co-fermentation (SSCF), the optimal temperature for cellulase hydrolysis of lignocellulose is much higher than that of fermentation. Successful use of SSCF requires optimization of the expression of PPP genes at elevated temperatures. This study examined the combinatorial expression of PPP genes at high temperature. The results revealed that over-expression of TAL1 and TKL1 in Saccharomyces cerevisiae (S. cerevisiae) at 30 °C and over-expression of all PPP genes at 36 °C resulted in the highest ethanol productivities. Furthermore, combinatorial over-expression of PPP genes derived from S. cerevisiae and a thermostable yeast Kluyveromyces marxianus allowed the strain to ferment xylose with ethanol productivity of 0.51 g/L/h, even at 38 °C. These results clearly demonstrate that xylose metabolism can be improved by the utilization of appropriate combinations of thermostable PPP genes in high-temperature production of ethanol.

The Structure of an Archaeal ß-Glucosaminidase Provides Insight into Glycoside Hydrolase Evolution.

The archaeal exo-ß-d-glucosaminidase (GlmA) is a dimeric enzyme that hydrolyzes chitosan oligosaccharides into monomer glucosamines. GlmA is a member of the glycosidase hydrolase (GH)-A superfamily-subfamily 35 and is a novel enzyme in terms of its primary structure. Here, we present the crystal structure of GlmA in complex with glucosamine at 1.27 Å resolution. The structure reveals that a monomeric form of GlmA shares structural homology with GH42 ß-galactosidases, whereas most of the spatial positions of the active site residues are identical to those of GH35 ß-galactosidases. We found that upon dimerization, the active site of GlmA changes shape, enhancing its ability to hydrolyze the smaller substrate in a manner similar to that of homotrimeric GH42 ß-galactosidase. However, GlmA can differentiate glucosamine from galactose based on one charged residue while using the "evolutionary heritage residue" it shares with GH35 ß-galactosidase. Our study suggests that GH35 and GH42 ß-galactosidases evolved by exploiting the structural features of GlmA.

Crystal structure of an acetyl esterase complexed with acetate ion provides insights into the catalytic mechanism.

We previously reported the crystal structure of an acetyl esterase (TcAE206) belonging to carbohydrate esterase family 3 from Talaromyces cellulolyticus. In this study, we solved the crystal structure of an S10A mutant of TcAE206 complexed with an acetate ion. The acetate ion was stabilized by three hydrogen bonds in the oxyanion hole instead of a water molecule as in the structure of wild-type TcAE206. Furthermore, the catalytic triad residue His182 moved 0.8 Å toward the acetate ion upon substrate entering the active site, suggesting that this movement is necessary for completion of the catalytic reaction.

Sarcopenia is a risk factor for the recurrence of hepatocellular carcinoma after curative treatment.

BACKGROUND AND AIM: Sarcopenia, initially proposed as decreased of muscle mass and strength, is associated with aging and malignant diseases. The aim of the present study was to determine whether there is a correlation between sarcopenia and the recurrence of hepatocellular carcinoma (HCC) after curative treatment. METHODS: We conducted a retrospective analysis of consecutive naive patients with HCC who underwent curative resection or radiofrequency ablation. To eliminate the influence of cause or the severity of liver damage, subjects were limited to those with HCC with hepatitis C-related cirrhosis and Child-Pugh class A liver function. Patients were assessed using computed tomographic measurement of muscle mass at the level of the third lumbar (L3) vertebrae, the L3 skeletal muscle index (L3 SMI). Sarcopenia was defined by using previously published, sex-specific cut-off value. RESULTS: Sarcopenia was present in 61 of 92 patients. Patients' median age was 71.5 years (range, 47-84), and the baseline characteristics of patients were comparable between patients with and without sarcopenia except for sex, serum albumin level, prothrombin time, diabetes mellitus and body mass index. Recurrence rates at 1, 3 and 5 years were 39.1%,77.1%,81.7% for patients with sarcopenia and 23.5%,59.5% and 75.7% for patients without sarcopenia, respectively (P = 0.03). Multivariate Cox analysis revealed that sarcopenia and preoperative α-fetoprotein of more than 40 ng/mL were significant independent factors for recurrence. CONCLUSION: Sarcopenia is a risk factor for recurrence in patients with HCC who were treated with curative treatment.

The crystal structure of isoniazid-bound KatG catalase-peroxidase from Synechococcus elongatus PCC7942.

Isoniazid (INH) is one of the most effective antibiotics against tuberculosis. INH is a prodrug that is activated by KatG. Although extensive studies have been performed in order to understand the mechanism of KatG, even the binding site of INH in KatG remains controversial. In this study, we determined the crystal structure of KatG from Synechococcus elongatus PCC7942 (SeKatG) in a complex with INH at 2.12-Šresolution. Three INH molecules were bound to the molecular surface. One INH molecule was bound at the entrance to the ε-edge side of heme (designated site 1), another was bound at the entrance to the γ-edge side of heme (site 2), and another was bound to the loop structures in front of the heme propionate side chain (site 3). All of the interactions between KatG and the bound INH seemed to be weak, being mediated mainly by van der Waals contacts. Structural comparisons revealed that the identity and configuration of the residues in site 1 were very similar among SeKatG, Burkholderia pseudomallei KatG, and Mycobacterium tuberculosis KatG. In contrast, sites 2 and 3 were structurally diverse among the three proteins. Thus, site 1 is probably the common KatG INH-binding site. A static enzymatic analysis and thermal shift assay suggested that the INH-activating reaction does not proceed in site 1, but rather that this site may function as an initial trapping site for the INH molecule. Database: The atomic coordinates and structure factors have been deposited in the Protein Data Bank under the accession number 3WXO.

Crystal structure of the catalase-peroxidase KatG W78F mutant from Synechococcus elongatus PCC7942 in complex with the antitubercular pro-drug isoniazid.

Isoniazid (INH) is a pro-drug that has been extensively used to treat tuberculosis. INH is activated by the heme enzyme catalase-peroxidase (KatG), but the mechanism of the activation is poorly understood, in part because the INH binding site has not been clearly established. Here, we observed that a single-residue mutation of KatG from Synechococcus elongatus PCC7942 (SeKatG), W78F, enhances INH activation. The crystal structure of INH-bound KatG-W78F revealed that INH binds to the heme pocket. The results of a thermal-shift assay implied that the flexibility of the SeKatG molecule is increased by the W78F mutation, allowing the INH molecule to easily invade the heme pocket through the access channel on the γ-edge side of the heme.

[A case of multiple liver abscesses associated with Streptococcus salivarius in a patient with chronic periodontitis].

Streptococcus salivarius is an oral commensal bacterium that rarely causes disease in humans. Here, we report a case of liver abscess associated with S. salivarius in a 41-year-old woman who presented with continuous abdominal discomfort, fatigue, and fever. She was diagnosed with multiple liver abscesses; she underwent percutaneous transhepatic abscess drainage. Thereafter, S. salivarius was isolated in all bacterial cultures of the drained abscesses, and it was sensitive to penicillins. She made a good recovery after treatment. In the absence of an infective source other than chronic periodontitis, the cause of liver abscesses was attributed to oral S. salivarius. S. salivarius is a normal oral commensal, and oral commensals must be considered if the infective origin of liver abscess cannot be determined.

Crystallization and preliminary X-ray diffraction studies of La1 from Liocheles australasiae.

A novel scorpion venom peptide, La1 from Liocheles australasiae, with a molecular weight of 7.8 kDa, is presumed to possess a single von Willebrand factor type C (VWC) domain, a common protein module, based on the position of eight Cys residues in its sequence. The biological function of La1 is still unknown. Deciphering its three-dimensional structure will be helpful in understanding its biological function. La1 was crystallized by the sitting-drop vapour-diffusion method using magnesium sulfate as a precipitant. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a=63.0, b=30.2, c=32.3 Å, ß=108.5°, and diffracted to 1.9 Šresolution. The calculated VM based on one molecule per asymmetric unit was 1.87 Å3 Da(-1). The solvent content was 34.1%.

The 2.2†Šresolution structure of the catalase-peroxidase KatG from Synechococcus elongatus PCC7942.

The crystal structure of catalase-peroxidase from Synechococcus elongatus PCC7942 (SeKatG) was solved by molecular replacement and refined to an Rwork of 16.8% and an Rfree of 20.6% at 2.2 Šresolution. The asymmetric unit consisted of only one subunit of the catalase-peroxidase molecule, including a protoporphyrin IX haem moiety and two sodium ions. A typical KatG covalent adduct was formed, Met248-Tyr222-Trp94, which is a key structural element for catalase activity. The crystallographic equivalent subunit was created by a twofold symmetry operation to form the functional dimer. The overall structure of the dimer was quite similar to other KatGs. One sodium ion was located close to the proximal Trp314. The location and configuration of the proximal cation site were very similar to those of typical peroxidases such as ascorbate peroxidase. These features may provide a structural basis for the behaviour of the radical localization/delocalization during the course of the enzymatic reaction.

Low-dose rectal diclofenac for prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis: a randomized controlled trial.

BACKGROUND: Acute pancreatitis is a common complication of endoscopic retrograde cholangiopancreatography (ERCP). Rectal nonsteroidal anti-inflammatory drugs (specifically, 100 mg of diclofenac or indomethacin) have shown promising prophylactic activity in post-ERCP pancreatitis (PEP). However, the 100-mg dose is higher than that ordinarily used in Japan. METHODS: We performed a prospective randomized controlled study to evaluate the efficacy of low-dose rectal diclofenac for the prevention of PEP. Patients who were scheduled to undergo ERCP were randomized to receive a saline infusion either with 50 mg of rectal diclofenac (diclofenac group) or without (control group) 30 min before ERCP. The dose of diclofenac was reduced to 25 mg in patients weighing <50 kg. The primary outcome measure was the occurrence of PEP. RESULTS: Enrollment was terminated early because the planned interim analysis found a statistically significant intergroup difference in the occurrence of PEP. A total of 104 patients were eligible for this study; 51 patients received rectal diclofenac. Twelve patients (11.5%) developed PEP: 3.9% (2/51) in the diclofenac group and 18.9% (10/53) in the control group (p = 0.017). After ERCP, the incidence of hyperamylasemia was not significantly different between the two groups. Post-ERCP pain was significantly more frequent in the control group than in the diclofenac group (37.7 vs. 7.8%, respectively; p < 0.001). There were no adverse events related to diclofenac. CONCLUSIONS: Low-dose rectal diclofenac can prevent PEP.