[Interaction between root exudates of medicinal plants and rhizosphere microorganisms and its application in ecological planting of Chinese medicinal materials].

The rhizosphere is an important place for material exchange between medicinal plants and soil. Root exudates are the medium of material and signal exchange between plants and soil and are the key factors in the regulation of rhizosphere microecology. Rhizosphere microorganisms are an important part of the rhizosphere microecology of medicinal plants, and the interaction between root exudates and rhizosphere microorganisms has an important influence on the growth and quality formation of medicinal plants. Rational utilization of the interaction between root exudates and rhizosphere microorganisms of medicinal plants is one of the important ways to ensure the healthy growth of medicinal plants and promote the development of ecological planting of Chinese medicinal materials. In the paper, the research status of root exudates and rhizosphere microorganisms of medicinal plants in recent years was summarized. The interaction mechanism between root exudates and rhizosphere microorganisms of medicinal plants, as well as the influence of rhizosphere microorganisms on the growth of medicinal plants, were analyzed. In addition, the advantages and promoting effects of intercropping ecological planting mode on rhizosphere microecology of medicinal plants and quality improvement of Chinese medicinal materials were explained, providing a good basis for the study of the interaction among medicinal plants, microorganisms, and soil. Furthermore, it could produce important theoretical and practical significance for the ecological planting and sustainable utilization of medicinal plants.

Impaired proton pumping in cytochrome c oxidase upon structural alteration of the D pathway.

Cytochrome c oxidase is a membrane-bound enzyme, which catalyses the one-electron oxidation of four molecules of cytochrome c and the four-electron reduction of O(2) to water. Electron transfer through the enzyme is coupled to proton pumping across the membrane. Protons that are pumped as well as those that are used for O(2) reduction are transferred though a specific intraprotein (D) pathway. Results from earlier studies have shown that replacement of residue Asn139 by an Asp, at the beginning of the D pathway, results in blocking proton pumping without slowing uptake of substrate protons used for O(2) reduction. Furthermore, introduction of the acidic residue results in an increase of the apparent pK(a) of E286, an internal proton donor to the catalytic site, from 9.4 to ~11. In this study we have investigated intramolecular electron and proton transfer in a mutant cytochrome c oxidase in which a neutral residue, Thr, was introduced at the 139 site. The mutation results in uncoupling of proton pumping from O(2) reduction, but a decrease in the apparent pK(a) of E286 from 9.4 to 7.6. The data provide insights into the mechanism by which cytochrome c oxidase pumps protons and the structural elements involved in this process.

Sequence-specific assignments of proton NMR resonance peaks and analysis of secondary structural elements of LC1, a novel antibacterial polypeptide.

LC1 is a type of novel antibacterial polypeptide secreted by a Bacillus subtilis strain. It consists of 47 residues. Using bioengineering, LC1 was expressed in E.coli DH5alpha by using recombinant plasmid PBVAB16. By means of two-dimensional DQF-COSY, TOCSY and NOESY spectroscopies, protons of all 47 residues are identified. The studies show that the secondary structures of LC1 are principally anti-parallel beta sheets and extended conformations. It was speculated that there may be a hydrophobic core around Trp(23) in its three-dimensional structure.