Differences in glycemic trends due to reconstruction methods after proximal gastrectomy from the perspective of continuous glucose-monitoring.

PURPOSE: In recent years, clinicians have focused on the importance of preventing hypoglycemia. We evaluated the impact of different reconstruction procedures after proximal gastrectomy on glycemic variability in non-diabetic patients with gastric cancer. METHODS: This prospective observational study was conducted between April 2020 and March 2023. Flash continuous glucose-monitoring, a novel method for assessing glycemic control, was used to evaluate the glycemic profiles after gastrectomy. A flash continuous glucose-monitoring sensor was placed subcutaneously at the time of discharge, and glucose trends were evaluated for 2 weeks. RESULTS: The anastomotic methods for proximal gastrectomy were esophagogastrostomy in 10 patients and double-tract reconstruction in 10 patients. The time below this range (glucose levels < 70 mg/dL) was significantly higher in the double-tract reconstruction group than in the esophagogastrostomy group (p = 0.049). A higher nocturnal time below this range was significantly correlated with an older age and double-tract reconstruction (p = 0.025 and p = 0.025, respectively). CONCLUSION: These findings provide new insights into reconstruction methods after proximal gastrectomy by assessing postoperative hypoglycemia in non-diabetic patients with gastric cancer.

Investigating Cytoglobin Expression in Colon Cancer: Clinicopathological Insights from Immunohistochemical Analysis.

BACKGROUND/AIM: Cytoglobin (Cygb), a protein involved in cellular oxygen metabolism and protection, has garnered attention owing to its potential role in the initiation and progression of cancer, particularly colon cancer (CC). This study investigated the expression and significance of Cygb in CC. PATIENTS AND METHODS: This study included 145 patients who underwent R0 surgery for CC (clinical stage II/III) at our institution between January 2007 and December 2014. Immunohistochemical analysis was performed to evaluate the Cygb expression patterns in CC tissues. Additionally, the correlation between Cygb expression levels and the clinicopathological characteristics of patients with CC was investigated. RESULTS: Colon cancer tissues were categorized into high-expression (95 cases) and low-expression (50 cases) groups. Cygb was highly expressed in well-differentiated cases, whereas its expression decreased in poorly differentiated cases. No significant differences in other clinicopathological factors were observed between the two groups. Cygb expression had no significant effect on recurrence-free survival or overall survival. CONCLUSION: This study contributes to the growing understanding of Cygb expression and its significance in CC. The expression of Cygb in CC was found to be unrelated to the recurrence rate and prognosis, but showed a correlation with differentiation status.

Simultaneous detection of polarization states and wavefront by an angular variant micro-retarder-lens array.

We have demonstrated simultaneous detection of the polarization states and wavefront of light using a 7 × 7 array of angular variant micro-retarder-lenses. Manipulating the angular variant polarization with our optical element allows us to determine the two-dimensional distribution of polarization states. We have also proposed a calibration method for polarization measurements using our micro-retarder-lens array, allowing accurate detection of polarization states with an ellipticity of ± 0.01 and an azimuth of ± 1.0°. We made wavefront measurements using the micro-retarder-lens array, achieving a resolution of 25 nm. We conducted simultaneous detection of the polarization states and wavefront on four types of structured beam as samples. The results show that the two-dimensional distributions of the polarization states and wavefront for the four types of structured light are radially and azimuthally polarized beams, as well as left- and right-hand optical vortices. Our sensing technology has the potential to enhance our understanding of the nature of light in the fields of laser sciences, astrophysics, and even ophthalmology.

Prognostic Impact of Stromal Profiles Educated by Gastric Cancer.

BACKGROUND: Cancer-associated fibroblasts exhibit diversity and have several subtypes. The underlying relationship between the diversity of cancer-associated fibroblasts and their effect on gastric cancer progression remains unclear. In this study, mesenchymal stem cells were differentiated into cancer-associated fibroblasts with gastric cancer cell lines; clinical specimens were used to further investigate the impact of cancer-associated fibroblast diversity on cancer progression. METHODS: Nine gastric cancer cell lines (NUGC3, NUGC4, MKN7, MKN45, MKN74, FU97, OCUM1, NCI-N87, and KATOIII) were used to induce mesenchymal stem cell differentiation into cancer-associated fibroblasts. The cancer-associated fibroblasts were classified based on ACTA2 and PDPN expression. Cell function analysis was used to examine the impact of cancer-associated fibroblast subtypes on cancer cell phenotype. Tissue samples from 97gastric patients who underwent gastrectomy were used to examine the clinical significance of each subtype classified according to cancer-associated fibroblast expression. RESULTS: Co-culture of mesenchymal stem cells with nine gastric cancer cell lines revealed different subtypes of ACTA2 and PDPN expression in differentiated cancer-associated fibroblasts. Cancer-associated fibroblast subtypes with high ACTA2 plus PDPN expression levels significantly increased gastric cancer cell migration, invasion, and proliferation. The cancer-associated fibroblast subtype with ACTA2 plus PDPN expression was an independent prognostic factor along with lymph node metastasis for patients who had gastric cancer and were undergoing surgery. CONCLUSIONS: Cancer-associated fibroblasts are educated by gastric cancer cells during the development of cancer-associated fibroblast diversity. Differentiated cancer-associated fibroblasts with distinct expression patterns could affect gastric cancer progression and enable prognostic stratification for gastric cancer.

Catabolic System of 5-Formylferulic Acid, a Downstream Metabolite of a ß-5-Type Lignin-Derived Dimer, in Sphingobium lignivorans SYK-6.

Sphingobium lignivorans SYK-6 can assimilate various lignin-derived aromatic compounds, including a ß-5-type (phenylcoumaran-type) dimer, dehydrodiconiferyl alcohol (DCA). SYK-6 converts DCA to a stilbene-type intermediate via multiple reaction steps and then to vanillin and 5-formylferulic acid (FFA). Here, we first elucidated the catabolic pathway of FFA, which is the only unknown pathway in DCA catabolism. Then, we identified and characterized the enzyme-encoding genes responsible for this pathway. Analysis of the metabolites revealed that FFA was converted to 5-carboxyferulic acid (CFA) through oxidation of the formyl group, followed by conversion to ferulic acid by decarboxylation. A comprehensive analysis of the aldehyde dehydrogenase genes in SYK-6 indicated that NAD+-dependent FerD (SLG_12800) is crucial for the conversion of FFA to CFA. LigW and LigW2, which are 5-carboxyvanillic acid decarboxylases involved in the catabolism of a 5,5-type dimer, were found to be involved in the conversion of CFA to ferulic acid, and LigW2 played a significant role. The ligW2 gene forms an operon with ferD, and their transcription was induced during growth in DCA.

Lensless single-fiber ghost imaging.

We demonstrate lensless single-fiber ghost imaging, which allows illumination and collection using a single optical fiber without a transmission-type system. Speckle patterns with relative coincidence degrees of 0.14 were formed by image reconstruction using improved differential ghost imaging. Employing fiber with a diameter of 105 µm, we achieved a spatial resolution of 0.05 mm in an observing area of 9m m 2, at a working distance of 10 mm. Compared to a conventional neuroendoscope at a power density of 94m W/c m 2, our imaging could be realized by extremely weak illumination at a laser power density of 0.10m W/c m 2. Using our lensless single-fiber ghost imaging, with 30,000 speckle patterns and implementing a diffuser, we attained an average coincidence degree of 0.45.

Analysis of surgical outcomes and risk factors for anastomotic leakage following trans-hiatal resection of esophagogastric junction cancer.

BACKGROUND: The trans-hiatal lower esophagectomy is considered less invasive than the trans-thoracic esophagectomy for resection of esophagogastric junction (EGJ) cancer. However, the optimal procedure remains controversial and should be determined while considering both oncological and safety aspects. METHODS: This retrospective study comprised 124 patients that underwent curative resection for EGJ cancer. The study analysis included 93 patients with tumor centers located within 2 cm of the EGJ. Clinicopathological findings and surgical outcomes were compared between patients treated using trans-hiatal and trans-thoracic approaches. RESULTS: Sixty-three patients underwent lower esophagectomy using the trans-hiatal approach (TH-G). The remaining 30 patients underwent esophagectomy using the trans-thoracic approach (TT-E). The TH-G group were older, had a lower prevalence of lymphatic spread, shorter length of esophageal invasion, and shorter operative duration compared to the TT-E group. Although no significant differences in the frequency of postoperative complications, a higher proportion of patients in the TH-G group developed anastomotic leakage (16% vs. 7%, p = 0.33). Univariate and multivariate analyses demonstrated that cardiac comorbidity was an independent risk factor for anastomotic leakage (odds ratio, 5.24; 95% CI, 1.06-25.9; P < 0.05) in TH-G group. Further examination revealed that preoperative cardiothoracic ratio (CTR) with 50% or greater could be surrogate marker as risk factor for anastomotic leakage in TH-G group (35% vs. 7.5%, p < 0.05). CONCLUSIONS: The trans-hiatal approach can be used for resection of EGJ cancer. However, special attention should be paid to the prevention of anastomotic leakage in patients with cardiac comorbidities or a large preoperative CTR.

Successful selective production of vanillic acid from depolymerized sulfite lignin and its application to poly(ethylene vanillate) synthesis.

Towards lignin upgrading, vanillic acid (VA), a lignin-derived guaiacyl compound, was produced from sulfite lignin for successfully synthesizing poly(ethylene vanillate), an aromatic polymer. The engineered Sphingobium sp. SYK-6-based strain in which the genes responsible for VA/3-O-methyl gallic acid O-demethylase and syringic acid O-demethylase were disrupted was able to produce vanillic acid (VA) from the mixture consisting of acetovanillone, vanillin, VA, and other low-molecular-weight aromatics obtained by Cu(OH)2-catalyzed alkaline depolymerization of sulfite lignin and membrane fractionation. From the bio-based VA, methyl-4-(2-hydroxyethoxy)-3-methoxybenzoate was synthesized via methylesterification, hydroxyethylation, and distillation, and then it was subjected to polymerization catalyzed by titanium tetraisopropoxide. The molecular weight of the obtained poly(ethylene vanillate) was evaluated to be Mw = 13,000 (Mw/Mn = 1.99) and its melting point was 261 °C. The present work proved that poly(ethylene vanillate) is able to be synthesized using VA produced from lignin for the first time.

Stereoinversion via Alcohol Dehydrogenases Enables Complete Catabolism of ß-1-Type Lignin-Derived Aromatic Isomers.

Sphingobium sp. strain SYK-6 is an efficient aromatic catabolic bacterium that can consume all four stereoisomers of 1,2-diguaiacylpropane-1,3-diol (DGPD), which is a ring-opened ß-1-type dimer. Recently, LdpA-mediated catabolism of erythro-DGPD was reported in SYK-6, but the catabolic pathway for threo-DGPD was as yet unknown. Here, we elucidated the catabolism of threo-DGPD, which proceeds through conversion to erythro-DGPD. When threo-DGPD was incubated with SYK-6, the Cα hydroxy groups of threo-DGPD (DGPD I and II) were initially oxidized to produce the Cα carbonyl form (DGPD-keto I and II). This initial oxidation step is catalyzed by Cα-dehydrogenases, which belong to the short-chain dehydrogenase/reductase (SDR) family and are involved in the catabolism of ß-O-4-type dimers. Analysis of seven candidate genes revealed that NAD+-dependent LigD and LigL are mainly involved in the conversion of DGPD I and II, respectively. Next, we found that DGPD-keto I and II were reduced to erythro-DGPD (DGPD III and IV) in the presence of NADPH. Genes involved in this reduction were sought from Cα-dehydrogenase and ldpA-neighboring SDR genes. The gene products of SLG_12690 (ldpC) and SLG_12640 (ldpB) catalyzed the NADPH-dependent conversion of DGPD-keto I to DGPD III and DGPD-keto II to DGPD IV, respectively. Mutational analysis further indicated that ldpC and ldpB are predominantly involved in the reduction of DGPD-keto. Together, these results demonstrate that SYK-6 harbors a comprehensive catabolic enzyme system to utilize all four ß-1-type stereoisomers through successive oxidation and reduction reactions of the Cα hydroxy group of threo-DGPD with a net stereoinversion using multiple dehydrogenases. IMPORTANCE In many catalytic depolymerization processes of lignin polymers, aryl-ether bonds are selectively cleaved, leaving carbon-carbon bonds between aromatic units intact, including dimers and oligomers with ß-1 linkages. Therefore, elucidating the catabolic system of ß-1-type lignin-derived compounds will aid in the establishment of biological funneling of heterologous lignin-derived aromatic compounds to value-added products. Here, we found that threo-DGPD was converted by successive stereoselective oxidation and reduction at the Cα position by multiple alcohol dehydrogenases to erythro-DGPD, which is further catabolized. This system is very similar to that developed to obtain enantiopure alcohols from racemic alcohols by artificially combining two enantiocomplementary alcohol dehydrogenases. The results presented here demonstrate that SYK-6 has evolved to catabolize all four stereoisomers of DGPD by incorporating this stereoinversion system into its native ß-1-type dimer catabolic system.

Cystic degeneration during neo-adjuvant chemotherapy predicts squamous metaplasia of triple negative breast cancer: report of two cases.

Neo-adjuvant chemotherapy (NAC) has become a standard treatment for advanced breast cancer because of the advantage of monitoring drug sensitivity and enabling breast-conserving therapy. The changes during NAC are also important to know the biological characteristics of the tumor. We experienced two cases with cystic degeneration and enhancement of the cyst wall during NAC for triple negative breast cancer (TNBC). They were diagnosed to have breast cancer with squamous metaplasia. In case 1, a 37-year-old woman with right breast cancer diagnosed as TNBC, T3N3M0, Stage 3b was treated with NAC. MRI showed a cystic degeneration with a diameter of 3.5 cm and enhancement of the cyst wall, and the other nodules were extinguished. The histopathological finding of the surgical specimen revealed solid tubular carcinoma with squamous metaplasia. In case 2, a 58-year-old woman with right breast cancer diagnosed as HER2 enriched subtype, T2N0M0 stage 2 was treated with NAC containing trastuzumab. The post-NAC MRI showed extinguishment of the mass in the right breast, but showed a cystic lesion with 24 mm in diameter and enhancement of its wall in the left breast. She underwent breast conserving surgery for bilateral breast cancer, and histopathological finding of the surgical specimen indicated complete remission of right breast cancer and squamous cell carcinoma developed in the left breast. These changes are impressive and remind us that there are metaplastic changes (especially for squamous metaplasia) with resistance to chemotherapy.

The Catabolic System of Acetovanillone and Acetosyringone in Sphingobium sp. Strain SYK-6 Useful for Upgrading Aromatic Compounds Obtained through Chemical Lignin Depolymerization.

Acetovanillone is a major aromatic monomer produced in oxidative/base-catalyzed lignin depolymerization. However, the production of chemical products from acetovanillone has not been explored due to the lack of information on the microbial acetovanillone catabolic system. Here, the acvABCDEF genes were identified as specifically induced genes during the growth of Sphingobium sp. strain SYK-6 cells with acetovanillone and these genes were essential for SYK-6 growth on acetovanillone and acetosyringone (a syringyl-type acetophenone derivative). AcvAB and AcvF produced in Escherichia coli phosphorylated acetovanillone/acetosyringone and dephosphorylated the phosphorylated acetovanillone/acetosyringone, respectively. AcvCDE produced in Sphingobium japonicum UT26S carboxylated the reaction products generated from acetovanillone/acetosyringone by AcvAB and AcvF into vanilloyl acetic acid/3-(4-hydroxy-3,5-dimethoxyphenyl)-3-oxopropanoic acid. To demonstrate the feasibility of producing cis,cis-muconic acid from acetovanillone, a metabolic modification on a mutant of Pseudomonas sp. strain NGC7 that accumulates cis,cis-muconic acid from catechol was performed. The resulting strain expressing vceA and vceB required for converting vanilloyl acetic acid to vanillic acid and aroY encoding protocatechuic acid decarboxylase in addition to acvABCDEF successfully converted 1.2 mM acetovanillone to approximately equimolar cis,cis-muconic acid. Our results are expected to help improve the yield and purity of value-added chemical production from lignin through biological funneling. IMPORTANCE In the alkaline oxidation of lignin, aromatic aldehydes (vanillin, syringaldehyde, and p-hydroxybenzaldehyde), aromatic acids (vanillic acid, syringic acid, and p-hydroxybenzoic acid), and acetophenone-related compounds (acetovanillone, acetosyringone, and 4'-hydroxyacetophenone) are produced as major aromatic monomers. Also, base-catalyzed depolymerization of guaiacyl lignin resulted in vanillin, vanillic acid, guaiacol, and acetovanillone as primary aromatic monomers. To date, microbial catabolic systems of vanillin, vanillic acid, and guaiacol have been well characterized, and the production of value-added chemicals from them has also been explored. However, due to the lack of information on the microbial acetovanillone and acetosyringone catabolic system, chemical production from acetovanillone and acetosyringone has not been achieved. This study elucidated the acetovanillone/acetosyringone catabolic system and demonstrates the potential of using these genes for the production of value-added chemicals from these compounds.

Pseudomonas sp. NGC7 as a microbial chassis for glucose-free muconate production from a variety of lignin-derived aromatics and its application to the production from sugar cane bagasse alkaline extract.

cis,cis-Muconate (ccMA) is a promising platform for use in synthesizing various polymers. A glucose-free ccMA production using Pseudomonas sp. NGC7 from hardwood lignin-derived aromatic compounds was previously reported. In that system, syringyl nucleus compounds were essential for growth. Here, it is shown that NGC7 is available for glucose-free ccMA production even from a mixture of lignin-derived aromatics that does not contain syringyl nucleus compounds. By introducing a gene set for the protocatechuate (PCA)-shunt consisting of PCA 3,4-dioxygenase and PCA decarboxylase into an NGC7-derived strain deficient in PCA 3,4-dioxygenase and ccMA cycloisomerase, it was succeeded in constructing a ccMA-producing strain that grows on a lignin-derived aromatics mixture containing no syringyl nucleus compounds. Finally, it is demonstrated that the engineered strain produced ccMA from sugar cane bagasse alkaline extract in 18.7 mol%. NGC7 is thus shown to be a promising microbial chassis for biochemicals production from lignin-derived aromatics.

Benefit of home parenteral nutrition (HPN) and chemotherapy in patients with invasive lobular carcinoma developed peritoneal metastases.

The benefit of home parenteral nutrition (HPN) for patients with malnutrition due to peritoneal metastasis depends on the type of cancer. During the period 1999-2020, we treated 460 patients with metastatic and stage 4 breast cancer, 23 of whom were invasive lobular carcinoma (ILC). Of the 23 patients with ILC, 13 (57%) developed peritoneal metastasis, and 11 died of progression of peritoneal metastasis. Among these 11 patients, 2 patients who underwent surgery due to bowel obstruction, had no improvement, and died 1-4 months after surgery. The prognosis of the other 7 patients under BSC alone was poor, survival time were ranging from 1 to 5 months. The remaining two patients who were able to continue outpatient chemotherapy under HPN were able to prolong their survival time by 18 months and 26 months, respectively. We need to recognize that HPN and chemotherapy may prolong survival time in patients with peritoneal metastasis of ILC, and determine the indication for HPN based on the non-peritoneal life-threatening metastasis, length of treatment, availability of support for HPN management and outpatient chemotherapy, and the patient's willingness to accept it.

The eIF4E-binding protein Eap1 has similar but independent roles in cell growth and gene expression with the cytoplasmic deadenylase Ccr4.

eIF4E-binding proteins (4E-BPs) are translational repressors that compete with eIF4G for binding to eIF4E. Here we investigated the roles of yeast 4E-BPs, Eap1, and Caf20 in cell wall integrity pathway and gene expression. We found that eap1∆ mutation, but not caf20∆ mutation, showed synthetic growth defect with mutation in ROM2 gene encoding Rho1 GEF. The eap1∆ mutation also showed synthetic lethality with mutation in CCR4 gene encoding cytoplasmic deadenylase. Ccr4 functions in the degradation of LRG1 mRNA encoding Rho1 GAP. Eap1-Y109A L114A, which could not bind to eIF4E, did not suppress the synthetic lethality of eap1∆ ccr4∆ mutant, suggesting that 4E-binding of Eap1 is important for its function. We also found that eap1∆ mutant showed the derepression of stress response gene HSP12. 4E-binding of Eap1 was also required for the repression of HSP12 expression. Our results indicate that Eap1 has similar but independent roles in cell growth and gene expression with Ccr4.

[Nab-Paclitaxel plus Gemcitabine for Patients with Recurrence after Resection for Adenocarcinoma of the Pancreas].

PURPOSE: The purpose of this study was to clarify the predictors of efficacy of nab-paclitaxel plus gemcitabine(GnP)for patients with recurrence after resection for adenocarcinoma of the pancreas. METHOD: Patients who had received GnP at our hospital were divided into 2 groups; effective group and non-effective group and we compared them. In addition, we compared the therapeutic effect of patients between well-differentiated adenocarcinoma and moderately differentiated adenocarcinoma. Furthermore, we compared the efficacy depending on the time of recurrence. RESULTS: In patients with well-differentiated adenocarcinoma, the disease control rate was 93.6% and progression free survival was 8.6 months, whereas those in patients with moderately differentiated adenocarcinoma were 57.1% and 4.4 months, respectively. Patients who recurred at 7 months or later, had a better therapeutic response than the patients who recurred within 6 months after surgery. CONCLUSIONS: GnP may be effective in patients with well-differentiated adenocarcinoma and in patients who recurred at 7 months or later.

Stroke Volume Variation Monitoring to Minimize Blood Loss in Hepatocellular Carcinoma Resection.

BACKGROUND/AIM: We aimed to evaluate the correlation between stroke volume variation (SVV) and intraoperative blood loss (IBL) in hepatocellular carcinoma (HCC) resection and examine the perioperative utility of SVV-based management. PATIENTS AND METHODS: Ninety-five patients who underwent partial or sub-segmental hepatectomy for HCC between 2013 and 2019 at the University of Yamanashi Hospital were retrospectively analyzed. A correlation analysis between IBL and SVV was performed, and then all cases were divided into three groups: high, middle, and low-SVV groups. Perioperative short-term outcomes based on SVV groups were analyzed. RESULTS: There was a weak but significant negative correlation between SVV and IBL (ρ=-0.372, p<0.001). Comparative analysis revealed that low-SVV was associated with a high incidence of postoperative complications and blood transfusion (p=0.018 and 0.037, respectively), and high-SVV was not related with postoperative complications. CONCLUSION: SVV-based management is a significant and feasible strategy to achieve safe and exact surgical resection of HCC.

Early Drain Removal Regardless of Drain Fluid Amylase Level Might Reduce Risk of Postoperative Pancreatic Fistula.

BACKGROUND/AIM: Drains are frequently placed at the time of distal pancreatectomy (DP) to evacuate pancreatic juice and intra-abdominal exudate and obtain information on abdominal cavity status. However, the timing of drain removal remains debatable. Meanwhile, prolonged drain placement might increase the risk of postoperative pancreatic fistula (POPF), with a prevalence of 5-40%. Therefore, we examined the effect of removing the drain within postoperative day (POD) 3 on the risk of POPF development. PATIENTS AND METHODS: A total of 108 consecutive patients who underwent DP between April 2015 and March 2020 were examined and divided into two groups according to the day of drain removal; hence, for some patients, the drain was removed on POD 1 (POD 1 group) and for others on POD 3 (POD 3 group). Furthermore, risk factors, including drain fluid amylase (DFA) levels, for developing POPF were investigated. RESULTS: The overall rate of clinically relevant POPF was 4.6% and did not significantly differ between the POD 1 and POD 3 groups [4.5% and 4.9%, respectively (p=0.924)]. DFA levels on POD 1 did not significantly differ between patients with and without POPF. On POD 3 and POD 5, C-reactive protein (CRP) levels were significantly higher in patients with POPF than in those without (p=0.03 and p<0.001, respectively). CONCLUSION: Early drain removal regardless of DFA level may reduce the risk of developing POPF. CRP measured on POD 3 and POD 5 appeared to be a useful predictor of clinically relevant POPF.

Roles of two glutathione S-transferases in the final step of the ß-aryl ether cleavage pathway in Sphingobium sp. strain SYK-6.

Sphingobium sp. strain SYK-6 is an alphaproteobacterial degrader of lignin-derived aromatic compounds, which can degrade all the stereoisomers of ß-aryl ether-type compounds. SYK-6 cells convert four stereoisomers of guaiacylglycerol-ß-guaiacyl ether (GGE) into two enantiomers of α-(2-methoxyphenoxy)-ß-hydroxypropiovanillone (MPHPV) through GGE α-carbon atom oxidation by stereoselective Cα-dehydrogenases encoded by ligD, ligL, and ligN. The ether linkages of the resulting MPHPV enantiomers are cleaved by stereoselective glutathione (GSH) S-transferases (GSTs) encoded by ligF, ligE, and ligP, generating (ßR/ßS)-α-glutathionyl-ß-hydroxypropiovanillone (GS-HPV) and guaiacol. To date, it has been shown that the gene products of ligG and SLG_04120 (ligQ), both encoding GST, catalyze GSH removal from (ßR/ßS)-GS-HPV, forming achiral ß-hydroxypropiovanillone. In this study, we verified the enzyme properties of LigG and LigQ and elucidated their roles in ß-aryl ether catabolism. Purified LigG showed an approximately 300-fold higher specific activity for (ßR)-GS-HPV than that for (ßS)-GS-HPV, whereas purified LigQ showed an approximately six-fold higher specific activity for (ßS)-GS-HPV than that for (ßR)-GS-HPV. Analyses of mutants of ligG, ligQ, and both genes revealed that SYK-6 converted (ßR)-GS-HPV using both LigG and LigQ, whereas only LigQ was involved in converting (ßS)-GS-HPV. Furthermore, the disruption of both ligG and ligQ was observed to lead to the loss of the capability of SYK-6 to convert MPHPV. This suggests that GSH removal from GS-HPV catalyzed by LigG and LigQ, is essential for cellular GSH recycling during ß-aryl ether catabolism.

Discovery of novel enzyme genes involved in the conversion of an arylglycerol-ß-aryl ether metabolite and their use in generating a metabolic pathway for lignin valorization.

Microbial conversions known as "biological funneling" have attracted attention for their ability to upgrade heterogeneous mixtures of low-molecular-weight aromatic compounds obtained by chemical lignin depolymerization. ß-hydroxypropiovanillone (HPV) and its analogs can be obtained by chemoselective catalytic oxidation of lignin using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone/tert-butyl nitrite/O2, followed by cleavage of arylglycerol-ß-aryl ether with zinc. Sphingobium sp. strain SYK-6 can degrade HPV generated by the catabolism of arylglycerol-ß-aryl ether through 2-pyrone-4,6-dicarboxylate (PDC), a promising platform chemical. Therefore, production of PDC from HPV can be achieved using the HPV catabolic pathway. However, the pathway and genes involved in the catabolism of vanilloyl acetic acid (VAA) generated during HPV catabolism have not been investigated. In the present study, we isolated SLG_24960 (vceA), which encodes an enzyme that converts VAA into a coenzyme A (CoA) derivative of vanillate (vanilloyl-CoA) from SYK-6, by shotgun cloning. The analysis of a vceA mutant indicated that this gene is not required for VAA conversion in vivo, but it encodes a major enzyme catalyzing CoA-dependent VAA conversion in vitro. We also identified SLG_12450 (vceB), whose product can convert vanilloyl-CoA to vanillate. Enzyme genes besides vceA and vceB, which are necessary for the conversions of HPV to VAA and of vanillate to PDC, were introduced and expressed in Pseudomonas putida. The resulting engineered strain completely converted 1  mM HPV into PDC after 24  h. Our results suggest that the enzyme genes that are not required for the catabolic pathway in microorganisms but can be used for the conversion of target substrates are buried in microbial genomes. These genes are, thus, useful for designing metabolic pathways to produce value-added metabolites.

Bacterial Catabolism of ß-Hydroxypropiovanillone and ß-Hydroxypropiosyringone Produced in the Reductive Cleavage of Arylglycerol-ß-Aryl Ether in Lignin.

Sphingobium sp. strain SYK-6 converts four stereoisomers of arylglycerol-ß-guaiacyl ether into achiral ß-hydroxypropiovanillone (HPV) via three stereospecific reaction steps. Here, we determined the HPV catabolic pathway and characterized the HPV catabolic genes involved in the first two steps of the pathway. In SYK-6 cells, HPV was oxidized to vanilloyl acetic acid (VAA) via vanilloyl acetaldehyde (VAL). The resulting VAA was further converted into vanillate through the activation of VAA by coenzyme A. A syringyl-type HPV analog, ß-hydroxypropiosyringone (HPS), was also catabolized via the same pathway. SLG_12830 (hpvZ), which belongs to the glucose-methanol-choline oxidoreductase family, was isolated as the HPV-converting enzyme gene. An hpvZ mutant completely lost the ability to convert HPV and HPS, indicating that hpvZ is essential for the conversion of both the substrates. HpvZ produced in Escherichia coli oxidized both HPV and HPS and other 3-phenyl-1-propanol derivatives. HpvZ localized to both the cytoplasm and membrane of SYK-6 and used ubiquinone derivatives as electron acceptors. Thirteen gene products of the 23 aldehyde dehydrogenase (ALDH) genes in SYK-6 were able to oxidize VAL into VAA. Mutant analyses suggested that multiple ALDH genes, including SLG_20400, contribute to the conversion of VAL. We examined whether the genes encoding feruloyl-CoA synthetase (ferA) and feruloyl-CoA hydratase/lyase (ferB and ferB2) are involved in the conversion of VAA. Only FerA exhibited activity toward VAA; however, disruption of ferA did not affect VAA conversion. These results indicate that another enzyme system is involved in VAA conversion.IMPORTANCE Cleavage of the ß-aryl ether linkage is the most essential process in lignin biodegradation. Although the bacterial ß-aryl ether cleavage pathway and catabolic genes have been well documented, there have been no reports regarding the catabolism of HPV or HPS, the products of cleavage of ß-aryl ether compounds. HPV and HPS have also been found to be obtained from lignin by chemoselective catalytic oxidation by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone/tert-butyl nitrite/O2, followed by cleavage of the ß-aryl ether with zinc. Therefore, value-added chemicals are expected to be produced from these compounds. In this study, we determined the SYK-6 catabolic pathways for HPV and HPS and identified the catabolic genes involved in the first two steps of the pathways. Since SYK-6 catabolizes HPV through 2-pyrone-4,6-dicarboxylate, which is a building block for functional polymers, characterization of HPV catabolism is important not only for understanding the bacterial lignin catabolic system but also for lignin utilization.