• Journal of Life Science
• /
• v.13 no.2
• /
• pp.184-190
• /
• 2003

Myxococcus xanthus is a Gram negative, rod-shaped, soil bacterium that displays a social behaviors, and multicellular development upon nutrient deprivation. The csgA gene encoding a cell surface protein is essential for developmental behaviors including rippling, aggregation, fruiting body formation and sporulation. csgA mutants show normal vegetative growth, but lack all these developmental phenotypes. Expression of the CsgA (C-signal) specific genes are eliminated or dramatically reduced in csgA mutants. In order to identify components of C-signal transduction pathway, second site mutations were introduced into csgA mutants and were identified which can fully or partially restore development of csgA mutants (Rhie, H. G. et. al. 1989. J. Bacteriol. 171, 3268-3276). One of such csgA suppressor mutations, socD500 restores only sporulation to csgA mutants at 15$^{\circ}C$. The socD500 mutaion however eliminates the three basic developmental requirements, starvation, high cell density and a solid surface. Only sporulation, not accompanied with fruiting body formation is induced simply by shifting the temperature of vegetatively growing cells from $32^{\circ}C$ to $15^{\circ}C$. Spores induced by socD500 mutation is not as thick as that of wild-type fruiting body. In socD500 genetic background, two of ten C-signal dependent genes, $\Omega$DK4506 and $\Omega$DK4406 are more highly expressed in growing cells at $15^{\circ}C$. These results indicate that the socD500 mutation may be partly involved in the regulation of expression of two C-signal dependent genes and genes for sporulation in this transduction pathway.

• Korean Journal of Weed Science
• /
• v.30 no.3
• /
• pp.225-232
• /
• 2010

The effect of Protox expression site on herbicidal resistance was investigated in wild-type and transgenic rice plants imposed by peroxidizing herbicide oxyfluorfen. The transgenic rice systems involved the plastidal expression of Arabidopsis protoporphyrinogen oxidase (Protox; AP line) and the dual expression of Myxococcus xanthus Protox in chloroplasts and mitochondria (TTS line). The oxyfluorfen-treated TTS4 line showed the lower levels of cellular leakage and malonyldialdehyde and the sustained capacity of 5-aminolevulinic acid synthesis, compared to the oxyfluorfen-treated AP and wild-type lines. During oxyfluorfen action, the TTS4 line had greater herbicide resistance than the AP1 line, indicating that the dual expression of M. xanthus Protox in chloroplasts and mitochondria prevented the accumulation of photodynamic protoporphyrin IX more effectively than the expression of Arabidopsis Protox only in chloroplasts. These results suggest that the ectopic expression of Protox in mitochondria greatly contributes to the herbicidal resistance in rice plants.

• Proceedings of the Korean Society of Plant Biotechnology Conference
• /
• 2005.11a
• /
• pp.310-310
• /
• 2005

• Microbiology and Biotechnology Letters
• /
• v.30 no.3
• /
• pp.199-205
• /
• 2002

Gliding motility is defined as the movement of nonflagellated cells in the direction of its long axis on a solid surface and found in many phylogenetically diverse bacteria. Genetic, biochemical, ultrastructural, and behavioral studies have provided a wealth of information related to the mechanism of possible gliding apparatuses. Social motility of Myxococcus xanthus and the gliding of Synechocystis appear to rely on the function of type IV pili, similar to twitching motility of pseudomonas aeruginosa and Neisseria gonorrhoeae. In contrast, adventurous motility of M. xanthus and the gliding of filamentous cyanobacteria and Flavobacterium are not dependent on the pili. Instead, they appear to employ novel motility mechanisms that are currently being unveiled.

• Korean Journal of Weed Science
• /
• v.31 no.2
• /
• pp.134-145
• /
• 2011

The objectives of this study were to investigate fitness difference in growth and rice yield in herbicide-transgenic rice overexpressing Myxococcus xanthus and Arabidopsis thaliana protoporphyrinogen oxidase (Protox) genes and non-transgenic rice. We also aimed to determine whether these fitness differences are related to ALA synthesizing capacity, accumulation of terapyrroles, reactive oxygen species, lipid peroxidation, and antioxidative enzymes at different growth stages of rice. Plant height of the transgenic rice overexpressing M. xanthus (MX) and A. thaliana (AP37) Protox genes at 43, 50, and 65 days after transplanting (DAT) was significantly lower than that of WT. Number of tiller of PX as well as MX and AP37 at 50 and 65 DAT was significantly lower than that of WT. At harvest time, culm length and yield of MX, PX and AP37 and rice straw weight of MX and AP37 were significantly low compared with WT. The reduction of yield in MX, PX, and AP37 was caused by spikelets per panicle and 1000 grain weight, ripened grain, spikelets per panicle, 1000 grain weight, and ripened grain, respectively. On the other hand, 135 the reduction of yield in MX, PX, and AP37 was also observed in another yearly variation experiment. The reduction of rice growth in MX, PX, and AP37 was observed in seedling stage as well as growth duration in field. There were no differences in tetrapyrrole intermediate Proto IX, Mg-Proto IX and Mg-Proto IX monomethyl ester, reactive oxygen species ($H_2O_2$ and ${O_2}^-$), MDA, antioxidative enzymes (SOD, CAT, POX, APX, and GR) and chlorophyll between transgenic lines and wild type, indicating that accumulated tetrapyrrole intermediate and other parameters were not related to growth reduction in transgenic rice. However, ALA synthesizing capacity in MX, PX, and AP37 at one day after exposure to light and 52 DAT was significantly lower than that of WT. Further study is required to elucidate the mechanisms underlying the growth and yield difference between transgenic and WT lines.

• Korean Journal of Weed Science
• /
• v.30 no.2
• /
• pp.122-134
• /
• 2010

We investigated the levels of resistance and accumulation of terapyrroles, reactive oxygen species, lipid peroxidation, and antioxidative enzymes for reasons of growth reduction in herbicide-transgenic rice overexpressing Myxococcus xanthus, Arabidopsis thaliana, and human protoporphyrinogen oxidase (Protox) genes. The transgenic rice overexpressing M. xanthus (MX, MX1, PX), A. thaliana (AP31, AP36, AP37), and human (H45, H48, H49) Protox genes showed 43~65, 41~72 and 17~70-fold more resistance to oxyfluorfen, respectively, than the wild type. Among transgenic rice lines overexpressing Protox genes, several lines showed normal growth compared with the wild type, but several lines showed in reduction of plant height and shoot fresh weight under different light conditions. However, reduction of plant height of AP37 was much higher than other lines for the experimental period. On the other hand, the reduction of plant height and shoot fresh weight in the transgenic rice was higher in high light condition than in low light condition. Enhanced levels of Proto IX were observed in transgenic lines AP31, AP37, and H48 at 7 days after seeding (DAS) and transgenic lines PX, AP37, and H48 at 14 DAS relative to wild type. There were no differences in Mg-Proto IX of transgenic lines except for H41 and H48 and Mg-Proto IX monomethyl ester of transgenic lines except for MX, MX1, and PX. Although accumulation of tetrapyrrole intermediates was observed in transgenic lines, their tetrapyrrole accumulation levels were not enough to inhibit growth of transgenic rice. There were no differences in reactive oxygen species, MDA, ALA synthesizing capacity, and chlorophyll between transgenic lines and wild type indicating that accumulated tetrapyrrole intermediate were apparently not high enough to inhibit growth of transgenic rice. Therefore, the growth reduction in certain transgenic lines may not be caused by a single factor such as Proto IX, but by interaction of many other factors.

• Microbiology and Biotechnology Letters
• /
• v.45 no.3
• /
• pp.226-235
• /
• 2017

Carotenoids such as phytoene, lycopene, and ${\beta}-carotene$ are used as food colorants, animal feed supplements, and for human nutrition and cosmetic purposes. Previously, we reported the isolation of a novel marine bacterium, Kocuria gwangalliensis, which produces a pink-orange pigment. Phytoene desaturase (CrtI), encoded by the gene crtI, catalyzes lycopene formation from phytoene and is an essential enzyme in the early steps of carotenoid biosynthesis. CrtI is one of the key enzymes regulating carotenoid biosynthesis and has been implicated as a rate-limiting enzyme of the pathway in various carotenoid synthesizing organisms. Here, we report the cloning of the crtI gene responsible for lycopene biosynthesis from K. gwangalliensis. The gene consisted of 1,584 bases encoding 527 amino acid residues. The nucleotide sequence of the crtI gene was compared with that of other species, including Kocuria rhizophila and Myxococcus xanthus, and was found to be well conserved during evolution. An expression plasmid containing the crtI gene was constructed (pCcrt1), and Escherichia coli cells were transformed with this plasmid to produce a recombinant protein of approximately 57 kDa, corresponding to the molecular weight of phytoene desaturase. Lycopene biosynthesis was confirmed when the plasmid pCcrtI was co-transformed into E. coli containing the plasmid pRScrtEB carrying the crtE and crtB genes required for lycopene biosynthesis. The results from this study will provide valuable information on the primary structure of K. gwangalliensis CrtI at the molecular level.