• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.694-705
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• 2017

The aim of this study was to isolate and identify marine bacterium with anti-methicillin-resistant Staphylococcus aureus (MRSA) activity, and to purify the anti-MRSA compound, as well as to determine its activity and synergistic effects. Among the marine bacteria isolated in this study, the YJ-1 isolate had the strongest anti-MRSA activity. The YJ-1 isolate was identified on the basis of its biochemical characteristics and an analysis of 16S rRNA gene sequences. The YJ-1 isolate showed over 99.2% homology with Pseudomonas stutzeri, and was designated as a Pseudomonas sp. YJ-1. The optimal culture conditions were $25^{\circ}C$ and initial pH 7.0. For the purification of the anti-MRSA compounds, the YJ-1 was cultured in Pa PES-II medium, and the culture filtrates were extracted by ethyl acetate, hexane, and 80% MeOH. The 80% MeOH fraction was separated by a $C_{18}$ ODS column, silica gel chromatography and a reverse phase HPLC, to yield three anti-MRSA agents, the MR1, MR2, and MR3 compounds. When the MR1 compound of $250{\mu}g\;mL^{-1}$ concentration was applied to the MRSA cells, over 95% of bacterial cells was killed within 48 hr. Compared with vancomycin and ampicillin, the MR1 compound showed significant anti-MRSA activity. In addition, the anti-MRSA activity was increased by dose and time dependent manners. Furthermore, the combination of an MR1 compound with vancomycin produced a more rapid decrease in the MRSA cells than did the MR1 compound alone. Taken together, our results suggest that the Pseudomonas sp. YJ-1 and its anti-MRSA compounds could be employed as a natural antibacterial agent in MRSA infections.

• Journal of Life Science
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• v.33 no.10
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• pp.828-834
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• 2023

The cDNA that encodes transmembrane protein 258 (Tmem258) was cloned from Gryllus bimaculatus and named GbTmem258. This protein comprises 80 amino acids, has no N-glycosylation site, and contains five potential phosphorylation sites at two serines, two threonines, and one tyrosine. The predicted molecular mass of GbTmem258 is 9.06 kDa, and its theoretical isoelectric point is 5.5. The tertiary structure of GbTmem258 was predicted using the available secondary structure information, which suggests the presence of alpha helices (52.5%), random coils (22.5%), extended strands (16.25%), and beta turns (8.75%). Homology analysis revealed that GbTmem258 exhibits high similarity at the amino-acid level to Tmem258 found in other species. The effect of starvation and refeeding on GbTmem258 mRNA expression was also examined in this study. It was found that GbTmem258 mRNA expression in the hindgut progressively increased throughout the starvation period, peaking at almost 1.5 times the control level after six days of starvation. However, refeeding for one to two days after the six-day starvation period restored GbTmem258 mRNA expression to the control level. In fat body, GbTmem258 mRNA expression was almost 3-fold higher during starvation compared to the control level. Refeeding for one to two days after the six-day fast resulted in a decline in the expression to about a 2.5-fold increase over the control level. Throughout the starving and refeeding periods, no other tissues showed any discernible alterations in GbTmem258 mRNA expression.