〓 Research Area : Chemistry of Bio-signaling

Study on the molecular mechanisms that regulate
environmental stress responses in plants
In nature, plants are exposed to a combination of a wide variety of environmental stresses. To
sustain their growth, plants have developed robust mechanisms that integrate the stress signals
and then output the optimal adaptation response. The long-term goal of our research is to uncover the molecular mechanisms of how plants achieve the signal integration and its conversion
to the downstream response. In particular, our research focuses on stress signaling regulating
stomatal movement. Stomatal pores, which are formed by pairs of guard cells in the epidermis
especially of leaves, regulate gas exchange for photosynthesis and transpirational water loss.
Guard cells can perceive various stimuli such as light, CO2, pathogen infection, and various phytohormones such as abscisic acid, jasmonate, and salicylic acid, then transducing the inputs toa change in stomatal aperture. Using multidisciplinary approaches, we aim to reveal the detailed
mechanisms of signaling cascading from stress sensing to stomatal aperture regulation in guardcells. We also study the basic mechanisms of heavy metal and salt stress responses in plants
using model plants as well as cultured cells. Our research advance will contribute to develop
new technologies that improve crop productivity and safety.

〓 Prof.
MURATA Yoshiyuki〓 Research Area : Microbial Function

Frontiers of Nucleoside Antibiotics with Antifungal,Antiviral, and Antitrypanose Activities.
Nucleoside antibiotics comprise a group of microbial products, which has antifungal, antiviral and anti-protozoan activities. These antibiotics,
mostly produced by Streptomycetes species as their secondary metabolites, can inhibit parasite-specific processes such as viral proliferationand protozoan-specific metabolism. Despite the potential utility and yet increasing demands
for such powerful antibiotics, there are few successful utilization case of antiviral and anti-parasitic activity of the nucleoside antibiotics, due exclusively to the poor production yield and thedifficulty in identifying the biosynthetic genes in the genome of the producer strains. The present
research aims to develop an alternative strategy for production improvement by modifying thecellular machineries for transcription and translation to increase and maintain the biosynthetic enzymes without the need of cloning the biosyntheticgenes. RNA polymerase genes and ribosomal genes are altered on theNucleoside antibiotic producing strain
genome to increase and maintain the biosynthetic genes.
Streptomyces incarnatus NRRL8087.

Engineering RNA polymerase based on Molecular Dynamics Simulation and Density
Function Theory Calculation - QM/MM Estimation and Experimental Proof.

〓 Prof.
TAMURA Takashi

Computation of RNA polymerase
to improve the transcription rate.

RNA polymerase (RNAP) has four conserved residues, which
are collectively termed as rif-1 cluster residues, in the β-subunit.
Alteration of the rif-1 residues by site-directed mutation very
often results in production enhancement of the secondary metabolites. The residues are positioned to interact with the newly
synthesized mRNA, and they can regulate the polymerization
rate. Multiple combination of mutation can alter the interaction
between the β-subunit and RNA chain, which is also computedby MD-modeling and Density Function Theory calculation. Computation gives the theoretical consequence of residue change
in terms of interaction energy at the electronic levels, and experimental data gives clues on the most appropriate interaction forthe highly enhanced production of the secondary metabolite .

Graduate School of Environmental and Life Science, Okayama University43