Construction of the Thermostable D-Allulose 3-Epimerase from M30 by Protein Engineering Method.

D-Allulose 3-epimerase catalyzes C-3 epimerization between D-fructose and D-allulose was found in strain M30. The enzyme gene was cloned, and its recombinant enzyme and the mutant variants were expressed in Using the information of the sequence and model structure, we succeed in the improvement of melting temperature for the enzyme without significant loss of the enzyme activity by protein engineering method. The melting temperatures were increased by 2.

The rare sugar D-tagatose protects plants from downy mildews and is a safe fungicidal agrochemical.

The rare sugar D-tagatose is a safe natural product used as a commercial food ingredient. Here, we show that D-tagatose controls a wide range of plant diseases and focus on downy mildews to analyze its mode of action. It likely acts directly on the pathogen, rather than as a plant defense activator.

X-ray structure of Arthrobacter globiformis M30 ketose 3-epimerase for the production of D-allulose from D-fructose.

The X-ray structure of ketose 3-epimerase from Arthrobacter globiformis M30, which was previously reported to be a D-allulose 3-epimerase (AgD-AE), was determined at 1.96 Å resolution. The crystal belonged to the hexagonal space group P622, with unit-cell parameters a = b = 103.

Purification and characterization of d-allulose 3-epimerase derived from Arthrobacter globiformis M30, a GRAS microorganism.

An enzyme that catalyzes C-3 epimerization between d-fructose and d-allulose was found in Arthrobacter globiformis strain M30. Arthrobacter species have long been used in the food industry and are well-known for their high degree of safety. The enzyme was purified by ion exchange and hydrophobic interaction chromatographies and characterized as a d-allulose 3-epimerase (d-AE).

The rare sugar D-allose acts as a triggering molecule of rice defence via ROS generation.

Only D-allose, among various rare monosaccharides tested, induced resistance to Xanthomonas oryzae pv. oryzae in susceptible rice leaves with defence responses: reactive oxygen species, lesion mimic formation, and PR-protein gene expression. These responses were suppressed by ascorbic acid or diphenylene iodonium.

Phosphorylation of D-allose by hexokinase involved in regulation of OsABF1 expression for growth inhibition in Oryza sativa L.

We previously reported that a rare sugar D-allose, which is the D-glucose epimer at C3, inhibits the gibberellin-dependent responses such as elongation of the second leaf sheath and induction of α-amylase in embryo-less half seeds in rice (Fukumoto et al. 2011). D-Allose suppresses expressions of gibberellin-responsive genes downstream of SLR1 protein in the gibberellin-signaling through hexokinase (HXK)-dependent pathway.

A zinc-binding citrus protein metallothionein can act as a plant defense factor by controlling host-selective ACR-toxin production.

Metallothionein is a small cysteine-rich protein known to have a metal-binding function. We isolated three different lengths of rough lemon cDNAs encoding a metallothionein (RlemMT1, RlemMT2 and RlemMT3), and only RlemMT1-recombinant protein had zinc-binding activity. Appropriate concentration of zinc is an essential micronutrient for living organisms, while excess zinc is toxic.

Host-selective toxins produced by the plant pathogenic fungus Alternaria alternata.

Host-selective toxins (HSTs) produced by fungal plant pathogens are generally low-molecular-weight secondary metabolites with a diverse range of structures that function as effectors controlling pathogenicity or virulence in certain plant-pathogen interactions. There are now seven known diseases caused by Alternaria alternata in which HSTs are responsible for fungal pathogenesis. The pathogens have been defined as pathotypes of A.

Role of the pathotype-specific ACRTS1 gene encoding a hydroxylase involved in the biosynthesis of host-selective ACR-toxin in the rough lemon pathotype of Alternaria alternata.

The rough lemon pathotype of Alternaria alternata produces host-selective ACR-toxin and causes Alternaria leaf spot disease of the rootstock species rough lemon (Citrus jambhiri) and Rangpur lime (C. limonia). Genes controlling toxin production were localized to a 1.

Rare sugar D-allose suppresses gibberellin signaling through hexokinase-dependent pathway in Oryza sativa L.

One of the rare sugars, D-allose, which is the epimer of D-glucose at C3, has an inhibitory effect on rice growth, but the molecular mechanisms of the growth inhibition by D-allose were unknown. The growth inhibition caused by D-allose was prevented by treatment with hexokinase inhibitors, D-mannoheptulose and N-acetyl-D-glucosamine. Furthermore, the Arabidopsis glucose-insensitive2 (gin2) mutant, which is a loss-of-function mutant of the glucose sensor AtHXK1, showed a D-allose-insensitive phenotype.

D-Psicose induces upregulation of defense-related genes and resistance in rice against bacterial blight.

We examined rice responses to a rare sugar, d-psicose. Rice growth was inhibited by d-psicose but not by common sugars. Microarray analysis revealed that d-psicose treatment caused an upregulation of many defense-related genes in rice, and dose-dependent upregulation of these genes was confirmed by quantitative reverse-transcription polymerase chain reaction.

Nematicidal activities of 4-hydroxyphenylacetic acid and oidiolactone D produced by the fungus Oidiodendron sp.

Two nematicides, 4-hydroxyphenylacetic acid (4-HPA) (1) and oidiolactone D (2), were isolated from cultures of the fungus Oidiodendron sp., and their structures were identified by spectroscopic analyses. Compound 2 showed nematicidal activities against the root-lesion nematode, Pratylenchus penetrans, and the pine wood nematode, Bursaphelenchus xylophilus.

Role of the host-selective ACT-toxin synthesis gene ACTTS2 encoding an enoyl-reductase in pathogenicity of the tangerine pathotype of Alternaria alternata.

ABSTRACT The tangerine pathotype of Alternaria alternata produces host-selective ACT-toxin and causes Alternaria brown spot disease of tangerines and tangerine hybrids. Sequence analysis of a genomic BAC clone identified a previously uncharacterized portion of the ACT-toxin biosynthesis gene cluster (ACTT). A 1,034-bp gene encoding a putative enoyl-reductase was identified by using rapid amplification of cDNA ends and polymerase chain reaction and designated ACTTS2.

A rare sugar, d-allose, confers resistance to rice bacterial blight with upregulation of defense-related genes in Oryza sativa.

We investigated responses of rice plant to three rare sugars, d-altrose, d-sorbose, and d-allose, due to establishment of mass production methods for these rare sugars. Root growth and shoot growth were significantly inhibited by d-allose but not by the other rare sugars. A large-scale gene expression analysis using a rice microarray revealed that d-allose treatment causes a high upregulation of many defense-related, pathogenesis-related (PR) protein genes in rice.

Nematicidal activity of 5-hydroxymethyl-2-furoic acid against plant-parasitic nematodes.

A nematicide, 5-hydroxymethyl-2-furoic acid (1), was isolated from cultures of the fungus Aspergillus sp. and its structure was identified by spectroscopic analysis. Compound 1 showed effective nematicidal activities against the pine wood nematode Bursaphelenchus xylophilus and the free-living nematode Caenorhabditis elegans without inhibitory activity against plant growth, but 1 did not show any effective nematicidal activity against Pratylenchus penetrans.

Sensitivity to Alternaria alternata toxin in citrus because of altered mitochondrial RNA processing.

Specificity in the interaction between rough lemon (Citrus jambhiri Lush.) and the fungal pathogen Alternaria alternata rough lemon pathotype is determined by a host-selective toxin, ACR-toxin. Mitochondria from rough lemon are sensitive to ACR-toxin whereas mitochondria from resistant plants, including other citrus species, are resistant.