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A Gram-positive, aerobic, non-motile, non-spore-forming, short rod-shaped strain, NEAU-LLCT, was isolated from cow dung in Shangzhi city, Heilongjiang Province, northeast China and identified by a polyphasic taxonomic study. Colonies was light yellow, round, with entire margin. Strain NEAU-LLCT was grown at 15–45℃ and pH 6.0–10.0. NaCl concentration ranged from 0 to 5% (W/V). The 16S rRNA gene sequence of NEAU-LLCT showed the high similarities with Microbacterium kyungheense JCM 18735T (98.5%), Microbacterium trichothecenolyticum JCM 1358T (98.3%) and Microbacterium jejuense JCM 18734T (98.2%). The whole-cell sugars were glucose, rhamnose, and ribose. The menaquinones contained MK-12 and MK-13. Ornithine, glutamic acid, lysine, and a small amount of alanine and glycine were the amino acids in the hydrolyzed products of the cell wall. The major fatty acids were iso-C16:0, iso-C18:0, anteiso-C15:0 and anteiso-C17:0. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid. The genome of NEAU-LLCT was 4,369,375 bp and G + C content is 70.28 mol%. A combination of DNA-DNA hybridization result and some phenotypic characteristics demonstrated that strain NEAU-LLCT could be distinguished from its closely related strains. Therefore, the strain NEAU-LLCT was considered to represent a novel specie and was named Microbacterium helvum sp. (Type strain NEAU-LLCT =CCTCC AA 2018026T = JCM 32661T).

SUMMARYSchistosoma japonicum, a human blood fluke, causes a parasitic disease affecting millions of people in Asia. Thioredoxin–glutathione system ofS. japonicumplays a critical role in maintaining the redox balance in parasite, which is a potential target for development of novel antischistosomal agents. Here we cloned the gene ofS. japonicumthioredoxin (SjTrx), expressed and purified the recombinant SjTrx inEscherichia coli. Functional assay shows that SjTrx catalyses the dithiothreitol (DTT) reduction of insulin disulphide bonds. The coupling assay of SjTrx with its endogenous reductase, thioredoxin glutathione reductase fromS. japonicum(SjTGR), supports its biological function to maintain the redox homeostasis in the cell. Furthermore, the crystal structure of SjTrx in the oxidized state was determined at 2·0 Å resolution, revealing a typical architecture of thioredoxin fold. The structural information of SjTrx provides us important clues for understanding the maintenance function of redox homeostasis inS. japonicumand pathogenesis of this chronic disease.

Thioredoxin glutathione reductase from Schistosoma japonicum (SjTGR), a multifunctional enzyme, plays a vital role in antioxidant pathways and is considered to be a potential drug target for the development of antischistosomal chemotherapy. In this study, two constructs of a truncated form of SjTGR without the last two residues (Sec597-Gly598) were cloned, overexpressed and purified using wild-type and codon-optimized genes. Only SjTGR from the wild-type gene was found to form a complex with flavin adenine dinucleotide (FAD), which could be crystallized in the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 84.185, b = 86.47, c = 183.164 Å, at 295 K using the hanging-drop vapour-diffusion method. One dimer was present in the crystallographic asymmetric unit and the calculated Matthews coefficient (VM) and solvent content were 2.6 Å(3) Da(-1) and 52.8%, respectively. Structural determination of SjTGR is in progress using the molecular-replacement method.