Benzylic and aryl hydroxylations of m-xylene by o-xylene dioxygenase from Rhodococcus sp. strain DK17.

Kim, Dockyu,Choi, Ki Young,Yoo, Miyoun,Choi, Jung Nam,Lee, Choong Hwan,Zylstra, Gerben J,Kang, Beom Sik,Kim, Eungbin Springer International 2010 Applied microbiology and biotechnology Vol.86 No.6

<P>Escherichia coli cells expressing Rhodococcus DK17 o-xylene dioxygenase genes were used for bioconversion of m-xylene. Gas chromatography-mass spectrometry analysis of the oxidation products detected 3-methylbenzylalcohol and 2,4-dimethylphenol in the ratio 9:1. Molecular modeling suggests that o-xylene dioxygenase can hold xylene isomers at a kink region between alpha6 and alpha7 helices of the active site and alpha9 helix covers the substrates. m-Xylene is unlikely to locate at the active site with a methyl group facing the kink region because this configuration would not fit within the substrate-binding pocket. The m-xylene molecule can flip horizontally to expose the meta-position methyl group to the catalytic motif. In this configuration, 3-methylbenzylalcohol could be formed, presumably due to the meta effect. Alternatively, the m-xylene molecule can rotate counterclockwise, allowing the catalytic motif to hydroxylate at C-4 yielding 2,4-dimethylphenol. Site-directed mutagenesis combined with structural and functional analyses suggests that the alanine-218 and the aspartic acid-262 in the alpha7 and the alpha9 helices play an important role in positioning m-xylene, respectively.</P>

폐경 전·후 여성의 골밀도 및 골대사 지표에 영향을 미치는 요인

박지연 (Park,Jiyoun),최미연 (Choi,Miyoun ),이선희 (Lee,Seonheui),최윤호 (Choi,Yoonho ),박유경 (Park,Yookyoung ) 韓國營養學會 2011 Journal of Nutrition and Health Vol.44 No.1

The purpose of this study was to examine the association among bone mineral density (BMD), biochemical bone markers, nutrients, and salt intake in premenopausal and postmenopausal women. We evaluated 431 subjects who visited a health promotion center of a university hospital between January 2008 and July 2009. We excluded those who were taking medications or who had an endocrine disorder affecting osteoporosis. The subjects were divided into premenopausal (n = 283) and postmenopausal (n = 143) women. We evaluated the correlation among BMD of the lumbar spine, femoral neck, and total femoral, as well as biochemical bone markers, hormone, serum profiles, general characteristics, nutrient intakes, and food intake frequencies. From a stepwise multiple regression analysis, lumbar spine BMD was positively correlated with weight (p < 0.001) and negatively correlated with osteocalcin (OC)(p < 0.001), Femoral neck BMD was positively correlated with weight (p < 0.001) and negatively correlated with C-telopeptide (CTx) and al-kaline phosphatase (ALP)(p < 0.001, p < 0.05). In premenopausal women, femoral total BMD was positively correlated with BMI (p < 0.001) and negatively correlated with CTx (p < 0.001). In postmenopausal women, lumbar spine BMD was positively correlated with calcium intake (p < 0.01) and negatively correlated with sodium intake (p < 0.01). Femoral neck and femoral total BMD were both positively correlated with weight (p < 0.001), and femoral neck BMD was negatively correlated with age and ALP (p < 0.001, p < 0.05). Femoral total BMD was negatively correlated with age and OC (p < 0.001, p < 0.01). These results suggest that reducing sodium intake may play an important role delaying bone resorption and preventing a decrease in BMD. (Korean J Nutr 2011 44 (1): 29 ~ 40)

Differential degradation of bicyclics with aromatic and alicyclic rings by Rhodococcus sp. strain DK17.

Kim, Dockyu,Yoo, Miyoun,Choi, Ki Young,Kang, Beom Sik,Kim, Tai Kyoung,Hong, Soon Gyu,Zylstra, Gerben J,Kim, Eungbin American Society for Microbiology 2011 Applied and environmental microbiology Vol.77 No.23

<P>The metabolically versatile Rhodococcus sp. strain DK17 is able to grow on tetralin and indan but cannot use their respective desaturated counterparts, 1,2-dihydronaphthalene and indene, as sole carbon and energy sources. Metabolite analyses by gas chromatography-mass spectrometry and nuclear magnetic resonance spectrometry clearly show that (i) the meta-cleavage dioxygenase mutant strain DK180 accumulates 5,6,7,8-tetrahydro-1,2-naphthalene diol, 1,2-indene diol, and 3,4-dihydro-naphthalene-1,2-diol from tetralin, indene, and 1,2-dihydronaphthalene, respectively, and (ii) when expressed in Escherichia coli, the DK17 o-xylene dioxygenase transforms tetralin, indene, and 1,2-dihydronaphthalene into tetralin cis-dihydrodiol, indan-1,2-diol, and cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene, respectively. Tetralin, which is activated by aromatic hydroxylation, is degraded successfully via the ring cleavage pathway to support growth of DK17. Indene and 1,2-dihydronaphthalene do not serve as growth substrates because DK17 hydroxylates them on the alicyclic ring and further metabolism results in a dead-end metabolite. This study reveals that aromatic hydroxylation is a prerequisite for proper degradation of bicyclics with aromatic and alicyclic rings by DK17 and confirms the unique ability of the DK17 o-xylene dioxygenase to perform distinct regioselective hydroxylations.</P>

Biotechnological Potential of Rhodococcus Biodegradative Pathways

( Dockyu Kim ),( Ki Young Choi ),( Miyoun Yoo ),( Gerben J. Zylstra ),( Eungbin Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.7

The genus Rhodococcus is a phylogenetically and catabolically diverse group that has been isolated from diverse environments, including polar and alpine regions, for its versatile ability to degrade a wide variety of natural and synthetic organic compounds. Their metabolic capacity and diversity result from their diverse catabolic genes, which are believed to be obtained through frequent recombination events mediated by large catabolic plasmids. Many rhodococci have been used commercially for the biodegradation of environmental pollutants and for the biocatalytic production of high-value chemicals from low-value materials. Recent studies of their physiology, metabolism, and genome have broadened our knowledge regarding the diverse biotechnological applications that exploit their catabolic enzymes and pathways.

Association Between Knowledge and Attitude About Aging and Life Satisfaction Among Older Koreans

Soonrim Suh,Heejung Choi,Choonji Lee,Miyoun Cha,Inhee Jo 한국간호과학회 2012 Asian Nursing Research Vol.6 No.3

Purpose: The purpose of this study was to measure knowledge and attitude about aging and life satisfaction among older Korean adults and to examine the influence of attitude and knowledge about aging on these adults’ life satisfaction. Methods: A cross-sectional and correlational design was used. A total of 405 older adults were surveyed using a written questionnaire at six elderly welfare centers in a metropolitan city in South Korea in mid April 2011. The data were analyzed using descriptive statistics, Pearson’s correlation analysis, and multiple regression. Results: The score of knowledge on aging was below the medium level. Attitude about aging was neutral, and life satisfaction was at the medium level. Variables such as female sex, age, economic status, monthly allowance, living with a spouse, self-rated overall health, knowledge and attitude about aging accounted for 33.8% of the total variance in predicting life satisfaction of the older adults. Older age and lower economic status reduced life satisfaction. Being female, having a monthly income of 300,000 Korea Republic Won or more, living with a spouse, and better knowledge and attitude about aging were associated with enhanced life satisfaction. Conclusion: The effect of knowledge and attitude about aging on life satisfaction is significant. Economic status, living with a spouse and self-rated overall health status are also predictive factors in life satisfaction. Consequently, nursing interventions for education and psychological support to increase knowledge about aging and induce a positive attitude towards it should be developed to improve older adults’ life satisfaction. Purpose: The purpose of this study was to measure knowledge and attitude about aging and life satisfaction among older Korean adults and to examine the influence of attitude and knowledge about aging on these adults’ life satisfaction. Methods: A cross-sectional and correlational design was used. A total of 405 older adults were surveyed using a written questionnaire at six elderly welfare centers in a metropolitan city in South Korea in mid April 2011. The data were analyzed using descriptive statistics, Pearson’s correlation analysis, and multiple regression. Results: The score of knowledge on aging was below the medium level. Attitude about aging was neutral, and life satisfaction was at the medium level. Variables such as female sex, age, economic status, monthly allowance, living with a spouse, self-rated overall health, knowledge and attitude about aging accounted for 33.8% of the total variance in predicting life satisfaction of the older adults. Older age and lower economic status reduced life satisfaction. Being female, having a monthly income of 300,000 Korea Republic Won or more, living with a spouse, and better knowledge and attitude about aging were associated with enhanced life satisfaction. Conclusion: The effect of knowledge and attitude about aging on life satisfaction is significant. Economic status, living with a spouse and self-rated overall health status are also predictive factors in life satisfaction. Consequently, nursing interventions for education and psychological support to increase knowledge about aging and induce a positive attitude towards it should be developed to improve older adults’ life satisfaction.