Pro-metastatic activity of AGR2 interrupts angiogenesis target bevacizumab efficiency via direct interaction with VEGFA and activation of NF-κB pathway.

Anterior gradient 2 (AGR2), an endoplasmic reticulum (ER)-resident protein-disulfide isomerase (PDI), is associated with cancer development and malignant progression. Here, we show that high level of AGR2 promotes the aggressive phenotype of prostate cancer (PCa) mouse models developed by either patient-derived xenografts or surgical intra-prostate implantation of PCa cells, associated with enrichment of the blood vessel network in tumor tissues. Angiogenesis markers VEGFR2 and CD34, accompanied with the invasive marker Vimentin, were predominantly stained in metastatic liver tissues. Secreted AGR2 was defined to enhance VEGFR2 activity as evidenced by physical interaction of purified recombinant human AGR2 (rhAGR2) with rhVEGFA through the formation of a disulfide bond. Mutant or deleted thioredoxin motif in rhAGR2 was also unable to bind to rhVEGFA that led to the significant abolishment in the vessel formation, but partially affecting the aggressive process, implicating alternative mechanisms are required for AGR2-conferring metastasis. Cytosolic AGR2 contributed to cell metastasis ascribed to its stabilizing effect on p65 protein, which subsequently activated the NF-κB and facilitated epithelial to mesenchymal transition (EMT). Importantly, GSH and cabozantinib, but not bevacizumab, effectively blocked the pro-angiogenic effect of rhAGR2 in vitro and in vivo, providing evidence that secreted AGR2 acts as a predictive biomarker for selection of angiogenesis-targeting therapeutic drugs based on its levels in the circular system.

Cloning and functional characterization of a phenolic acid decarboxylase from the liverwort Conocephalum japonicum.

Some commercially important vinyl derivatives are produced by the decarboxylation of phenolic acids. Enzymatically, this process can be achieved by phenolic acid decarboxylases (PADs), which are able to act on phenolic acid substrates such as ferulic and p-coumaric acid. Although many microbial PADs have been characterized, little is known regarding their plant homologs. Transcriptome sequencing in the liverworts has identified seven putative PADs, which share a measure of sequence identity with microbial PADs, but are typically much longer proteins. Here, a PAD-encoding gene was isolated from the liverwort species Conocephalum japonicum. The 1197 nt CjPAD cDNA sequence was predicted to be translated into a 398 residue protein. When the gene was heterologously expressed in Escherichia coli, its product exhibited a high level of PAD activity when provided with either p-coumaric or ferulic acid as substrate, along with the conversion of caffeic acid and sinapic acid to their corresponding decarboxylated products. Both N- and C-terminal truncation derivatives were non-functional. The transient expression in tobacco of a GFP/CjPAD fusion gene demonstrated that the CjPAD protein is expressed in the cytoplasm. It is first time a PAD was characterized from plants and the present investigation provided a candidate gene for catalyzing the formation of volatile phenols.

Functional characterization of a chalcone synthase from the liverwort Plagiochasma appendiculatum.

KEY MESSAGE: A chalcone synthase gene ( PaCHS ) was isolated and functionally characterized from liverwort. The ectopic expression of PaCHS in Marchantia paleacea callus raised the flavonoids content. Chalcone synthase (CHS; EC 2.3.1.74) is pivotal for the biosynthesis of flavonoid and anthocyanin pigments in plants. It produces naringenin chalcone by condensing one p-coumaroyl- and three malonyl-coenzyme A thioesters through a polyketide intermediate that is cyclized by intramolecular Claisen condensation. Although CHSs of higher plants have been extensively studied, enzyme properties of the CHSs in liverworts have been scarcely characterized. In this study, we report the cloning and characterization of CHS (designated as PaCHS) from the liverwort Plagiochasma appendiculatum. The gene product was 60-70 % identical with chalcone synthases from other species, and contained the characteristic conserved Cys-His-Asn catalytic triad. The recombinant PaCHS was able to catalyze p-coumaroyl-CoA and malonyl-CoA to generate naringenin in vitro. Heterologously expressed PaCHS protein showed similar kinetic properties to those of higher plant CHS. The ectopic expression of PaCHS in Marchantia paleacea callus raised the content of the total flavonoids. These results suggested that PaCHS played a key role in the flavonoids biosynthesis in liverworts. Furthermore, when the thallus of P. appendiculatum was treated with abiotic stress inducers methyl jasmonate, salicylic acid and abscisic acid, PaCHS expression was enhanced. This is the first time that a CHS in liverworts has been functionally characterized.

The Assessment of Volumetric Changes for Alveolar Ridge Preservation or Reconstruction by Three-dimensional Analysis at Posterior Extraction Sites with Severe Bone Defects Using DBBM-C Collagen Membrane and PRF: A Prospective and Randomized Clinical Trial.

STATEMENT OF PROBLEM: Volumetric resorption of the alveolar ridge often occurs following tooth extraction in both horizontal and vertical directions. There is a specific lack of evidence for alveolar ridge reconstruction at molar and premolar sites with severe bone resorption. PURPOSE: This randomized and controlled trial aimed to use three dimensional and linear analyses to evaluate volumetric changes of the alveolar bone following alveolar ridge reconstruction (ARR) at molar and premolar sites with severe bone resorption as compared with non-assisted socket healing be implant placement. MATERIAL AND METHODS: A total of 31 patients (15 males and 16 females) with more than 50% of hard tissue loss in one or more socket walls were recruited and randomized into either a test group (ARR after extraction using deproteinized bovine bone mineral with 10% collagen (DBBM-C) and platelet-rich fibrin (PRF) with a resorbable collagen membrane) or a control group (natural healing after extraction). Then, the clinical, linear, volumetric implant-related and patient-reported outcomes were analyzed after a 4-month healing process. RESULTS: Linear bone assessments revealed significantly greater gains of ridge width in the test group (25% in the mesial, mid-facial and distal aspects) and less reduction of vertical bone ridge than in the control group (P＜0.05). Furthermore, volumetric bone remodeling was significantly higher in the test group (ARR=35.1±34.9%, control=14.2±12.8%, P＜0.05). Patient-reported discomfort and keratinized mucosal changes were comparable between groups. CONCLUSIONS: Alveolar ridge reconstruction with a combination of DBBM-C, PRF, and a resorbable membrane at posterior sites with severe socket wall deficiency (＞ 50% bone loss) is a safe and more capable therapeutic method when compared with natural healing and non-assisted sockets. CLINICAL IMPLICATIONS: Collectively, our analyses demonstrated that alveolar ridge reconstruction represents an efficient method to maintain and augment crestal bone at posterior extraction sites with severe bone defects when assessed after four months of healing.

Cloning and functional characterization of a cinnamate 4-hydroxylase gene from the hornwort Anthoceros angustus.

Hornworts, as the sister group to liverworts and mosses, comprise bryophytes, which are critical in understanding the evolution of key land plant traits. Cinnamate 4-hydroxylase (C4H) catalyzes the second step of the phenylpropanoid pathway to synthesize the precursor of numerous phenolic compounds, such as lignin and flavonoids. However, C4H in the hornwort Anthoceros angustus has not yet been cloned and functionally characterized. In this work, we screened the transcriptome database of A. angustus and identified one C4H gene, AnanC4H. AnanC4H maintained conserved cytochrome P450 domains with other typical plant C4Hs. Ultraviolet B irradiation and exogenous application of methyl jasmonate (MeJA) induced the expression of AnanC4H to varying degrees. The coding sequence of AnanC4H was expressed in yeast, and the recombinant proteins were isolated. The recombinant proteins of AnanC4H catalyzed the conversion of trans-cinnamic acid to p-coumaric acid and catalyzed the conversion of 3-hydroxycinnamic acid to caffeic acid. AnanC4H showed higher affinity for trans-cinnamic acid than for 3-hydroxycinnamic acid, but there was no significant difference in the catalytic efficiency of AnanC4H for the two substrates in vitro. Moreover, the expression of AnanC4H in Arabidopsis thaliana led to an increase in both the lignin content and the number of lignified cells in stems. However, there was no significant change in flavonoid content in transgenic Arabidopsis plants.

Distinct clinical characteristics in stage III rectal cancer among different age groups and treatment outcomes after neoadjuvant chemoradiotherapy.

Background: There is a rapidly increasing incidence of early-onset colorectal cancer (EO-CRC) which threatens the survival of young people, while aging also represents a challenging clinical problem. Objectives: We aimed to investigate the differences in the clinical characteristics and prognosis in stage III rectal cancer (RC), to help optimize treatment strategies. Design and methods: This study included 757 patients with stage III RC, all of whom received neoadjuvant chemoradiotherapy and total mesorectal excision. The whole cohort was categorized as very early onset (VEO, ⩽30 years old), early onset (EO, >30 years old, ⩽50 years old), intermediate onset (IO, >50 years, ⩽70 years), or late onset (LO, >70 years old). Results: There were more female VEO patients than males, more mucinous adenocarcinoma, signet-ring cell carcinoma, pre-treatment cT4 stage, and higher pre-treatment serum carbohydrate antigen 19-9 compared with the other three groups. VEO patients had the worst survival with the highest RC-related mortality (34.5%), recurrence (13.8%), and metastasis (51.7%). LO patients had the highest non-RC-related mortality rate (16.6%). The Cox regression model showed VEO was a negative independent prognostic factor for disease-free survival [DFS, hazard ratio (HR): 2.830, 95% confidence interval (CI): 1.633-4.904, p < 0.001], distant metastasis-free survival (DMFS, HR: 2.969, 95% CI: 1.720-5.127, p < 0.001), overall survival (OS, HR: 2.164, 95% CI: 1.102-4.249, p = 0.025), and cancer-specific survival (CSS, HR: 2.321, 95% CI: 1.145-4.705, p = 0.020). LO was a negative independent factor on DFS (HR: 1.800, 95% CI: 1.113-2.911, p = 0.017), DMFS (HR: 1.903, 95% CI: 1.150-3.149, p = 0.012), OS (HR: 2.856, 95% CI: 1.745-4.583, p < 0.001), and CSS (HR: 2.248, 95% CI: 1.282-3.942, p = 0.005). VEO patients had better survival in the total neoadjuvant therapy-like (TNT-like) pattern on DFS (p = 0.039). IO patients receiving TNT-like patterns had better survival on DFS, OS, and CSS (p = 0.006, p = 0.018, p = 0.006, respectively). Conclusion: In stage III RC, VEO patients exhibited unique clinicopathological characteristics, with VEO a negative independent prognostic factor for DFS, DMFS, OS, and CSS. VEO and IO patients may benefit from a TNT-like treatment pattern.

Total neoadjuvant treatment to increase the clinical complete response rate for distal locally advanced rectal cancer (TESS): A study protocol of a prospective, open-label, multicenter, single-arm, phase 2 trial.

BACKGROUND: Standard treatment of locally advanced rectal cancer (LARC) was neoadjuvant chemoradiotherapy (CRT), followed by total mesorectal excision (TME). Total neoadjuvant treatment (TNT), a new concept, attempts to deliver both systemic chemotherapy and neoadjuvant CRT prior to surgery. Patients treated with neoadjuvant chemotherapy were more likely to show higher tumor regression. The objective of this trial was to increase complete clinical rate (cCR) for LARC patients by optimizing tumor response, using TNT regimen as compared to conventional chemoradiotherapy. TESS, a prospective, open-label, multicenter, single-arm, phase 2 study, is underway. METHODS: Main inclusion criteria include cT3-4aNany or cT1-4aN+ rectal adenocarcinoma aged 18-70y; Eastern Cooperative Oncology Group (ECOG) performance 0-1; location ≤5 cm from anal verge. Ninety-eight patients will receive 2 cycles of neoadjuvant chemotherapy Capeox (capecitabine + oxaliplatin) before, during, and after radiotherapy 50Gy/25 fractions, before TME (or other treatment decisions, such as Watch and Wait strategy) and adjuvant chemotherapy capecitabine 2 cycles. Primary endpoint is the cCR rate. Secondary endpoints include ratio of sphincter preservation strategy; pathological complete response rate and tumor regression grade distribution; local recurrence or metastasis; disease-free survival; locoregional recurrence-free survival; acute toxicity; surgical complications; long-term anal function; late toxicity; adverse effect, ECOG standard score, and quality of life. Adverse events are graded per Common Terminology Criteria for Adverse Events V5.0. Acute toxicity will be monitored during antitumor treatment, and late toxicity will be monitored for 3 years from the end of the first course of antitumor treatment. DISCUSSION: The TESS trial aims to explore a new TNT strategy, which is expected to increase the rate of cCR and sphincter preservation rate. This study will provide new options and evidence for a new sandwich TNT strategy in patients with distal LARC.

A nomogram for predicting 10-year cancer specific survival in patients with pathological T3N0M0 rectal cancer.

Background: The pathological T3N0M0 (pT3N0M0) rectal cancer is the earliest stage and has the best prognosis in the locally advanced rectal cancer, but the optimal treatment remains controversial. A reliable prognostic model is needed to discriminate the high-risk patients from the low-risk patients, and optimize adjuvant chemotherapy (ACT) treatment decisions by predicting the likelihood of ACT benefit for the target population. Patients and methods: We gathered and analyzed 276 patients in Sun Yat-sen University Cancer Center from March 2005 to December 2011. All patients underwent total mesorectal excision (TME), without preoperative therapy, and were pathologically proven pT3N0M0 rectal cancer with negative circumferential resection margin (CRM). LASSO regression model was used for variable selection and risk factor prediction. Multivariable cox regression was used to develop the predicting model. Optimum cut-off values were determined using X-Tile plot analysis. The 10-fold cross-validation was adopted to validate the model. The performance of the nomogram was evaluated with its calibration, discrimination and clinical usefulness. Results: A total of 188 patients (68.1%) had ACT and no patients had adjuvant radiotherapy. Age, monocyte percentage, carbohydrate antigen 19-9, lymph node dissection numbers and perineural invasion (PNI) were identified as significantly associated variables that could be combined for an accurate prediction risk of Cancer Specific Survival (CSS) for pT3N0M0 patients. The model adjusted for CSS showed good discrimination with a C-index of 0.723 (95% CI: 0.652-0.794). The calibration curves showed that the nomogram adjusted for CSS was able to predict 3-, 5-, and 10-year CSS accurately. The corresponding predicted probability was used to stratify high and low-risk patients (10-year CSS: 69.1% vs. 90.8%, HR = 3.815, 95%CI: 2.102-6.924, P < 0.0001). ACT improved overall survival (OS) in the low-risk patients (10-year OS: 91.9% vs. 83.3%, HR = 0.338, 95% CI: 0.135-0.848, P < 0.0001), while it did not exhibit a significant benefit in the high-risk patients. Conclusion: The present study showed that age, monocyte percentage, carbohydrate antigen 19-9, lymph node dissection numbers and PNI were independent prognostic factors for pT3N0M0 rectal cancer patients. A nomogram based on these prognostic factors effectively predicts CSS in patients, which can be conveniently used in clinical practice. ACT may improve overall survival in the low-risk patients. But the benefit of ACT was not seen in the high-risk patients.

Inhibition of fungal pathogenicity by targeting the H2S-synthesizing enzyme cystathionine ß-synthase.

The global emergence of antifungal resistance threatens the limited arsenal of available treatments and emphasizes the urgent need for alternative antifungal agents. Targeting fungal pathogenic functions is an appealing alternative therapeutic strategy. Here, we show that cystathionine ß-synthase (CBS), compared with cystathionine γ-lyase, is the major enzyme that synthesizes hydrogen sulfide in the pathogenic fungus Candida albicans. Deletion of CBS leads to deficiencies in resistance to oxidative stress, retarded cell growth, defective hyphal growth, and increased ß-glucan exposure, which, together, reduce the pathogenicity of C. albicans. By high-throughput screening, we identified protolichesterinic acid, a natural molecule obtained from a lichen, as an inhibitor of CBS that neutralizes the virulence of C. albicans and exhibits therapeutic efficacy in a murine candidiasis model. These findings support the application of CBS as a potential therapeutic target to fight fungal infections.

Towards a novel efficient T-DNA-based mutagenesis and screening system using green fluorescent protein as a vital reporter in the industrially important fungus Trichoderma reesei.

Agrobacterium-mediated T-DNA transfer has been proven to be an efficient strategy for insertional mutagenesis and elucidation of gene function in filamentous fungi. The implementation of large-scale T-DNA insertional mutagenesis requires the development of high-efficient transformation and high-throughput screening procedures. Here, using green fluorescent protein (GFP) as a vital marker, a highly efficient T-DNA-based mutagenesis and screening system was developed in Trichoderma reesei. The uridine auxotrophic T. reesei M23 as the host was transformed with A. tumefaciens EH105 strain harboring a binary vector pC-OEP, which beared the pyrG gene for primary selection on minimal medium without uridine and the egfp gene for fluorescence-based rapid screening of the mitotically stable transformants. The efficiency of transformation was up to 10-20 transformants per 10(5) target conidia. Microscopic examination revealed strong GFP expression and fluorescence emission in conidia, growing hyphae and mycelia. An effective and convenient screening procedure using 96-well plates and multilabel counter for fluorescence intensity counting was developed to rapidly identify the T-DNA tagged T. reesei mutants. Furthermore, the presence of T-DNA integration at random sites in the genome was confirmed by Southern blot analysis. This report of the T-DNA-based mutagenesis and rapid screening system using GFP as a vital reporter provides a promising strategy to speeding up the genome-scale T-DNA insertional mutagenesis and functional genomics analysis of this cellulolytic fungus T. reesei.

Keratinized mucosa augmentation guided by double xenogeneic collagen matrix membranes around implants in the posterior mandible: A case report.

RATIONALE: Traditional free gingival graft (FGG) technique is usually used for patients with insufficient peri-implant keratinized mucosa. However, this technique often requires a second surgical area which increases the pain as well as the risk of infection in patients. Xenogeneic collagen matrix (XCM) membrane technique can obtain good results for keratinized mucosa increment. PATIENT CONCERNS: The patient was a 66-year-old healthy female with loss of left mandibular first molar and second molar (FDI #36, #37) for 5 years. Two implants were placed submucosally for 3 months with no interference, while a stage II surgery was needed. DIAGNOSIS: Probing depth measurements suggested that the mesial, medial, and distal widths of buccal keratinized mucosa within the edentulous area were 0.5, 0.5, and 1 mm, respectively, which were insufficient to maintain the health of peri-implant tissues. INTERVENTIONS: Keratinized mucosa augmentation guided by XCM membranes was performed to increase the inadequate buccal keratinized mucosa. OUTCOMES: After 2 months of healing, the widths of mesial, medial, and distal buccal keratinized mucosa were 4, 3, and 3 mm, respectively, and the thickness of the augmented mucosa was 4 mm. Then a stage II surgery was followed. The patient was satisfied with the outcomes of keratinized mucosa augmentation. LESSONS: Keratinized mucosa augmentation guided by double XCM membrane technique can be applied to cases with keratinized mucosa width within 2 mm around implants.

miR-187-3p increases gemcitabine sensitivity in breast cancer cells by targeting FGF9 expression.

Breast cancer is the most common type of malignancy in women, which remains a significant health concern worldwide. Gemcitabine is a frequently applied anticancer pharmacological agent. However, the efficacy of gemcitabine is limited by chemoresistance. In the present study, a combination of reverse transcription quantitative-PCR, cell viability, flow cytometry, luciferase reporter assay and western blot analysis were performed to elucidate the potential effects of miR-187-3p on gemcitabine sensitivity in the breast cancer cell line, MDA-MB-231. The results revealed that miR-187-3p was significantly decreased in the breast cancer tumor tissues. Moreover, the overexpression of miR-187-3p significantly inhibited cell viability and promoted apoptosis in MDA-MB-231 cells. In addition, miR-187-3p overexpression enhanced the anti-proliferative and pro-apoptotic effects of gemcitabine, indicating that miR-187-3p regulated gemcitabine sensitivity in breast cancer cells. Mechanistically, miR-187-3p negatively regulated the expression of fibroblast growth factor 9 (FGF9) by binding to its 3'-untranslated region. Overexpression of FGF9 reversed the aforementioned effects of miR-187-3p overexpression on cell viability and apoptosis in the presence of gemcitabine. In conclusion, the present study indicated that miR-187-3p increased gemcitabine sensitivity in breast cancer cells by targeting FGF9 expression.

Structural and biochemical characterization of the plant type III polyketide synthases of the liverwort Marchantia paleacea.

Chalcone synthases (CHSs) of the type III polyketide synthases (PKSs), catalyze the formation of a tetraketide intermediate from a CoA-tethered starter and malonyl-CoA but use different cyclization mechanisms to produce distinct chemical scaffolds. Herein, we characterized CHS and CHS-like enzymes (designated MpCHS and MpCHSL1, 2 and 3) from Marchantia paleacea and determined the crystal structure of MpCHSL1. MpCHS catalyzed a Claisen condensation to form chalcone, while MpCHSLs catalyzed the formation of lactonized α-pyrones in vitro. Based on the structural, mutational and in vitro biochemical analyses, we established that MpCHSL1 is structurally and functionally closer to prototype CHS than stilbene synthase, and characterized the structural basis for the functional diversity of the type III PKSs. A chalcone-forming mutant of MpCHSL1 was build directed by the structural information. These findings pave the way for future studies to elucidate the functional diversity of type III PKSs in liverwort.

The isolation and functional characterization of three liverwort genes encoding cinnamate 4-hydroxylase.

The plant phenylpropanoid pathway is responsible for the synthesis of a wide variety of secondary metabolites. The second step in phenylpropanoid synthesis is carried out by the cytochrome P450 monooxygenase enzyme cinnamate 4-hydroxylase (C4H), which catalyzes the p-hydroxylation of trans-cinnamic acid to p-coumarate. Genes encoding C4H have been characterized in many vascular plant species, but as yet not in any bryophyte species. Here, a survey of the transcriptome sequences of four liverwort species was able to identify eight putative C4Hs. The three liverwort C4H genes taken forward for isolation and functional characterization were harbored by Plagiochasma appendiculatum (PaC4H) and Marchantia paleacea (MpC4H1 and MpC4H2). When the genes were heterologously expressed in yeast culture, an assay of enzyme activity indicated that PaC4H and MpC4H1 had a higher level of activity than MpC4H2. The favored substrate (trans-cinnamic acid) of all three liverwort C4Hs was the same as that of higher plant C4Hs. The co-expression of PaC4H in yeast cells harboring PaPAL (a P. appendiculatum ene encoding phenylalanine ammonia lyase) allowed the conversion of L-phenylalanine to p-coumaric acid. Furthermore, the expression level of PaC4H was enhanced after treatment with abiotic stress inducers UV irradiation or salicylic acid in the thallus of P. appendiculatum. The likelihood is that high activity C4Hs evolved in the liverworts and have remained highly conserved across the plant kingdom.

Cloning and functional characterization of a 4-coumarate CoA ligase from liverwort Plagiochasma appendiculatum.

Plant phenylpropanoids represent a large group of secondary metabolites which have played an important role in terrestrial plant life, beginning with the evolution of land plants from primitive green algae. 4-Coumarate: coenzyme A ligase (4CL) is a provider of activated thioester substrates within the phenylpropanoid synthesis pathway. Although 4CLs have been extensively characterized in angiosperm, gymnosperm and moss species, little is known of their functions in liverworts. Here, a 4CL homolog (designated as Pa4CL1) was isolated from the liverwort species Plagiochasma appendiculatum. The full-length cDNA sequence of Pa4CL1 contains 1644bp and is predicted to encode a protein with 547amino acids. The gene products were 40-50% identical with 4CL sequences reported in public databases. The recombinant protein was heterologously expressed in Escherichia coli and exhibited a high level of 4CL activity, catalyzing formation of hydroxycinnamate-CoA thioesters by a two-step reaction mechanism from corresponding hydroxycinnamic acids. Kinetic analysis indicated that the most favorable substrate for Pa4CL1 is p-coumaric acid. The transcription of Pa4CL1 was induced when P. appendiculatum thallus was treated with either salicylic acid or methyl jasmonate.

Functional characterization of a Plagiochasma appendiculatum flavone synthase I showing flavanone 2-hydroxylase activity.

FNS I is a 2-oxoglutarate dependent dioxygenase (2-ODD) found mainly in species of the Apiaceae family. Here, an FNS I cDNA sequence was isolated from the liverwort Plagiochasma appendiculatum (Aytoniaceae) and characterized. The recombinant protein exhibited high FNS I activity catalyzing the conversion of naringenin to apigenin and 2-hydroxynaringenin. The critical residue for flavanone-2-hydroxylation activity was Tyr240, as identified from homology modeling and site-directed mutagenesis. The recombinant protein also showed some flavonol synthase activity, as it can convert dihydrokaempferol to kaempferol. When the Leu311 residue was mutated to Phe, the enzyme's capacity to convert dihydrokaempferol to kaempferol was substantially increased. PaFNS I represents a 2-ODD in which a hydrophobic π-stacking interaction between the key residue and the naringenin A-ring determines 2-hydroxyflavanone formation.

A single amino acid determines the catalytic efficiency of two alkenal double bond reductases produced by the liverwort Plagiochasma appendiculatum.

Alkenal double bond reductases (DBRs) catalyze the NADPH-dependent reduction of the α,ß-unsaturated double bond of many secondary metabolites. Two alkenal double bond reductase genes PaDBR1 and PaDBR2 were isolated from the liverwort species Plagiochasma appendiculatum. Recombinant PaDBR2 protein had a higher catalytic activity than PaDBR1 with respect to the reduction of the double bond present in hydroxycinnamyl aldehydes. The residue at position 56 appeared to be responsible for this difference in enzyme activity. The functionality of a C56 to Y56 mutation in PaDBR1 was similar to that of PaDBR2. Further site-directed mutagenesis and structural modeling suggested that the phenol ring stacking between this residue and the substrate was an important determinant of catalytic efficiency.

Application of T-DNA insertional mutagenesis for improving cellulase production in the filamentous fungus Trichoderma reesei.

A T-DNA-tagged mutant library created by Agrobacterium-mediated transformation (AMT) was assayed for improvement of cellulase production. After 96-well plate screening for rapid growth on cellulose substrates followed by plate-clearing zone assay, three putative mutants, TA-32, TB-87 and TE-6, with enhanced cellulolytic ability were isolated, exhibiting 38%, 51% and 31% increase in total cellulase activity than the parental strain QM9414, respectively. Endoglucanase, cellobiohydrolase and ß-glucosidase activities as well as the hydrolysis efficiencies of the mutants were also improved. Moreover, T-DNA was shown to be integrated at a single site in the genomes of TA-32 and TE-6 while inserted at two copies into the genome of TB-87. Further, the sequences flanking the T-DNA insertion sites were successfully rescued, demonstrating the increased utility of T-DNA insertional mutagenesis for improvement of cellulase production as well as subsequent identification of the tagged genes relevant to cellulolytic ability.