Ornithinimicrobium cerasi sp. nov., isolated from the fruit of Cerasus pseudocerasus and emended description of the genus Ornithinimicrobium.

Strain CPCC 203383T, isolated from the surface-sterilized fruit of Cerasus pseudocerasus (Lindl.) G. Don, was taxonomically characterized based on a polyphasic investigation. It had the highest 16S rRNA gene sequence similarities with Ornithinimicrobium pekingense DSM 21552 (97.2 %) and O. kibberense DSM 17687T (97.2%). Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain formed a distinct phyletic branch within the genus Ornithinimicrobium and the whole genome sequence data analyses supported that strain CPCC 203383T was phylogenetically related to the Ornithinimicrobium species. The isolate shared a range of phenotypic patterns reported for members of the genus Ornithinimicrobium, but also had a range of cultural, physiological and biochemical characteristics that separated it from related Ornithinimicrobium species. The menaquinone was MK-8(H4). The polar lipid profile consisted of diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylinositol (PI) and unidentified lipids (ULs). The major fatty acids (>5 %) were iso-C15 : 0, anteiso-C15 : 0, iso-C16:0, 9-methyl C16 : 0, iso-C17 : 0 and anteiso-C17 : 0. The cell wall peptidoglycan contains l-ornithine as diagnostic diamino acid and an interpeptide bridge consisting of L-Orn←L-Ala←Gly←D-Asp. The combined genotypic and phenotypic data indicated that the isolate represents a novel species of the genus Ornithinimicrobium, for which the name Ornithinimicrobium cerasi sp. nov. is proposed, with CPCC 203383T(=NBRC 113522T=KCTC 49200T) as the type strain. The DNA G+C composition is 72.3 mol%. The availability of new data allows for an emended description of the genus Ornithinimicrobium.

Prediction of allosteric sites on protein surfaces with an elastic-network-model-based thermodynamic method.

Allostery is a rapid and efficient way in many biological processes to regulate protein functions, where binding of an effector at the allosteric site alters the activity and function at a distant active site. Allosteric regulation of protein biological functions provides a promising strategy for novel drug design. However, how to effectively identify the allosteric sites remains one of the major challenges for allosteric drug design. In the present work, a thermodynamic method based on the elastic network model was proposed to predict the allosteric sites on the protein surface. In our method, the thermodynamic coupling between the allosteric and active sites was considered, and then the allosteric sites were identified as those where the binding of an effector molecule induces a large change in the binding free energy of the protein with its ligand. Using the proposed method, two proteins, i.e., the 70 kD heat shock protein (Hsp70) and GluA2 alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor, were studied and the allosteric sites on the protein surface were successfully identified. The predicted results are consistent with the available experimental data, which indicates that our method is a simple yet effective approach for the identification of allosteric sites on proteins.

Identification of functionally key residues in AMPA receptor with a thermodynamic method.

AMPA receptor mediates the fast excitatory synaptic transmission in the central nervous system, and it is activated by the binding of glutamate that results in the opening of the transmembrane ion channel. In the present work, the thermodynamic method developed by our group was improved and then applied to identify the functionally key residues that regulate the glutamate-binding affinity of AMPA receptor. In our method, the key residues are identified as those whose perturbation largely changes the ligand binding free energy of the protein. It is found that besides the ligand binding sites, other residues distant from the binding cleft can also influence the glutamate binding affinity through a long-range allosteric regulation. These allosteric sites include the hinge region of the ligand binding cleft, the dimer interface of the ligand binding domain, the linkers between the ligand binding domain and the transmembrane domain, and the interface between the N-terminal domain and the ligand binding domain. Our calculation results are consistent with the available experimental data. The results are helpful for our understanding of the mechanism of long-range allosteric communication in the AMPA receptor and the mechanism of channel opening triggered by glutamate binding.

Nocardioides perillae sp. nov., isolated from surface-sterilized roots of Perilla frutescens.

A Gram-stain-positive, rod-shaped actinobacterium, designated strain I10A-01402(T), was isolated from surface-sterilized roots of a medicinal plant, Perilla frutescens, collected in a suburb of Beijing, China. Chemotaxonomically, the strain contained ll-diaminopimelic acid as the diagnostic diamino acid and MK-8(H4) as the predominant menaquinone. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The major fatty acids were C17 : 1ω9c, C18 : 1ω9c, C17 : 0, C16 : 0 and iso-C16 : 0. The genomic DNA G+C content was 70.4 mol%. 16S rRNA gene sequence analysis indicated that strain I10A-01402(T) belonged to the genus Nocardioides. Phylogenetic analyses based on 16S rRNA gene sequences showed that the isolate formed a robust cluster with Nocardioides ginsengisegetis Gsoil 485(T), N. koreensis MSL-09(T) and N. alkalitolerans KSL-1(T). On the basis of the evidence from our polyphasic taxonomic study, a novel species, Nocardioides perillae sp. nov., is proposed. The type strain is I10A-01402(T) ( = CPCC 203382(T)  = DSM 24552(T)  = KCTC 29022(T)).

Allonocardiopsis opalescens gen. nov., sp. nov., a new member of the suborder Streptosporangineae, from the surface-sterilized fruit of a medicinal plant.

An endophytic actinomycete, designated strain I10A-01259(T), was isolated from a surface-sterilized fruit of Lonicera maackii (Rupr.) Maxim., a medicinal plant, which was collected from a suburb of Beijing, China. Whole-cell hydrolysates of the isolate contained galactose and meso-diaminopimelic acid. The predominant phospholipids were phosphatidylglycerol and diphosphatidylglycerol; the menaquinones consisted mainly of MK-9, MK-11 and MK-12, with a minor amount of MK-10. The major fatty acids were iso-C16 : 0, anteiso-C15 : 0 and iso-C15 : 0. Comparative analysis of 16S rRNA gene sequences indicated that strain I10A-01259(T) was most closely related to Nocardiopsis arabia S186(T) (93.2 % sequence similarity), Thermobifida halotolerans YIM 90462(T) (93.0 %) and other strains of genera within the families Nocardiopsaceae and Thermomonosporaceae. On the phylogenetic tree based on 16S rRNA gene sequences, strain I10A-01259(T) fell within the radius of the suborder Streptosporangineae, in which the strain formed a distinct lineage next to the genera of the families Nocardiopsaceae and Thermomonosporaceae. Based on the data from our polyphasic taxonomic study, a novel genus and species, Allonocardiopsis opalescens gen. nov., sp. nov., are proposed within the suborder Streptosporangineae. The type strain of Allonocardiopsis opalescens is strain I10A-01259(T) ( = CPCC 203428(T)  = DSM 45601(T)  = KCTC 19844(T)).