Title: Elucidating the biodegradation pathway and catabolic genes of benzophenone-3 in Rhodococcus sp. S2-17 Baek JH, Kim KH, Lee Y, Jeong SE, Jin HM, Jia B, Jeon CO Ref: Environ Pollut, 299:118890, 2022 : PubMed
A new bacterium, Rhodococcus sp. S2-17, which could completely degrade an emerging organic pollutant, benzophenone-3 (BP-3), was isolated from contaminated sediment through an enrichment procedure, and its BP-3 catabolic pathway and genes were identified through metabolic intermediate and transcriptomic analyses and biochemical and genetic studies. Metabolic intermediate analysis suggested that strain S2-17 may degrade BP-3 using a catabolic pathway progressing via the intermediates BP-1, 2,4,5-trihydroxy-benzophenone, 3-hydroxy-4-benzoyl-2,4-hexadienedioic acid, 4-benzoyl-3-oxoadipic acid, 3-oxoadipic acid, and benzoic acid. A putative BP-3 catabolic gene cluster including cytochrome P450, flavin-dependent oxidoreductase, hydroxyquinol 1,2-dioxygenase, maleylacetate reductase, and alpha/beta hydrolase genes was identified through genomic and transcriptomic analyses. Genes encoding the cytochrome P450 complex that demethylates BP-3 to BP-1 were functionally verified through protein expression, and the functions of the other genes were also verified through knockout mutant construction and intermediate analysis. This study suggested that strain S2-17 might have acquired the ability to catabolize BP-3 by recruiting the cytochrome P450 complex and alpha/beta hydrolase, which hydrolyzes 4-benzoyl-3-oxoadipic acid to benzoic acid and 3-oxoadipic acid, genes, providing insights into the recruitment of genes of for the catabolism of emerging organic pollutants.
Title: Development of an antibody-based diagnostic method for the identification of Bemisia tabaci biotype B Baek JH, Lee HJ, Kim YH, Lim KJ, Lee SH, Kim BJ Ref: Pestic Biochem Physiol, 131:18, 2016 : PubMed
The whitefly Bemisia tabaci is a very destructive pest. B. tabaci is composed of various morphologically undistinguishable biotypes, among which biotypes B and Q, in particular, draw attention because of their wide distribution in Korea and differential potentials for insecticide resistance development. To develop a biotype-specific protein marker that can readily distinguishes biotypes B from other biotypes in the field, we established an ELISA protocol based on carboxylesterase 2 (COE2), which is more abundantly expressed in biotypes B compared with Q. Recombinant COE2 was expressed, purified and used for antibody construction. Polyclonal antibodies specific to B. tabaci COE2 [anti-COE2 pAb and deglycosylated anti-COE2 pAb (DG anti-COE2 pAb)] revealed a 3-9-fold higher reactivity to biotype B COE2 than biotype Q COE2 by Western blot and ELISA analyses. DG anti-COE2 pAb exhibited low non-specific activity, demonstrating its compatibility in diagnosing biotypes. Western blot and ELISA analyses determined that one of the 11 field populations examined was biotype B and the others were biotype Q, suggesting the saturation of biotype Q in Korea. DG anti-COE2 pAb discriminates B. tabaci biotypes B and Q with high specificity and accuracy and could be useful for the development of a B. tabaci biotype diagnosis kit for on-site field applications.
OBJECTIVES: Mood-stabilizing drugs, such as lithium (Li) and valproate (VPA), are widely used for the treatment of bipolar disorder, a disease marked by recurrent episodes of mania and depression. Growing evidence suggests that Li exerts neurotrophic and neuroprotective effects, leading to an increase in neural plasticity. The present study investigated whether other mood-stabilizing drugs produce similar effects in primary hippocampal neurons. METHODS: The effects of the mood-stabilizing drugs Li, VPA, carbamazepine (CBZ), and lamotrigine (LTG) on hippocampal dendritic outgrowth were examined. Western blotting analysis was used to measure the expression of synaptic proteins - that is, brain-derived neurotrophic factor (BDNF), postsynaptic density protein-95 (PSD-95), neuroligin 1 (NLG1), beta-neurexin, and synaptophysin (SYP). To determine neuroprotective effects, we used a B27-deprivation cytotoxicity model which causes hippocampal cell death upon removal of B27 from the culture medium. RESULTS: Li (0.5-2.0 mM), VPA (0.5-2.0 mM), CBZ (0.01-0.10 mM), and LTG (0.01-0.10 mM) significantly increased dendritic outgrowth. The neurotrophic effect of Li and VPA was blocked by inhibition of phosphatidylinositol 3-kinase, extracellular signal-regulated kinase, and protein kinase A signaling; the effects of CBZ and LTG were not affected by inhibition of these signaling pathways. Li, VPA, and CBZ prevented B27 deprivation-induced decreases in BDNF, PSD-95, NLG1, beta-neurexin, and SYP levels, whereas LTG did not. CONCLUSIONS: These results suggest that Li, VPA, CBZ, and LTG exert neurotrophic effects by promoting dendritic outgrowth; however, the mechanism of action differs. Furthermore, certain mood-stabilizing drugs may exert neuroprotective effects by enhancing synaptic protein levels against cytotoxicity in hippocampal cultures.
Title: Enhanced display of lipase on the Escherichia coli cell surface, based on transcriptome analysis Baek JH, Han MJ, Lee SH, Lee SY Ref: Applied Environmental Microbiology, 76:971, 2010 : PubMed
A cell surface display system was developed using Escherichia coli OmpC as an anchoring motif. The fused Pseudomonas fluorescens SIK W1 lipase was successfully displayed on the surface of E. coli cells, and the lipase activity could be enhanced by the coexpression of the gadBC genes identified by transcriptome analysis.
Title: Complete genome sequence of the diesel-degrading Acinetobacter sp. strain DR1 Jung J, Baek JH, Park W Ref: Journal of Bacteriology, 192:4794, 2010 : PubMed
The genus Acinetobacter is ubiquitous in soil, aquatic, and sediment environments and includes pathogenic strains, such as A. baumannii. Many Acinetobacter species isolated from various environments have biotechnological potential since they are capable of degrading a variety of pollutants. Acinetobacter sp. strain DR1 has been identified as a diesel degrader. Here we report the complete genome sequence of Acinetobacter sp. DR1 isolated from the soil of a rice paddy.
Title: Frequency Detection of Organophosphate Resistance Allele in Anopheles sinensis (Diptera: Culicidae) Populations by Real-time PCR Amplification of Specific Allele (rtPASA) Baek JH, Kim HW, Lee WJ, Lee SH Ref: Journal of Asia-Pacific Entomology, 9:375, 2006 : PubMed
A rapid, simple and accurate real-time PASA (PCR amplification of specific allele) (rtPASA) protocol was developed and optimized for the frequency estimation of the Glyl119Ser mutation in the type-I acetylcholinesterase locus, putatively associated with organophosphate resistance, in pooled DNA samples of Anopheles sinensis, a major vector mosquito of malaria in Korea. Performance of the rtPASA protocol was evaluated by comparing with the data generated from individual genotypings of a field population. The resistance allele frequency of the population (74.4%) predicted from the linear regression line of the rtPASA agreed well with that estimated from the individual genotyping (74.1%), demonstrating its reliability and accuracy. Using this rtPASA protocol, the resistance allele frequency in 10 local populations of An. sinensis was determined to range from 74.4% to 97.2%, suggestive of the widespread organophosphate resistance in An. sinensis in Korea.
Title: Identification and characterization of ace1-type acetylcholinesterase likely associated with organophosphate resistance in Plutella xylostella Baek JH, Kim JI, Lee DW, Chung BK, Miyata T, Lee SH Ref: Pesticide Biochemistry and Physiology, 81:164, 2005 : PubMed
Insensitive acetylcholinesterase (AChE) was determined to be primarily involved in a prothiofos-resistant (PR) strain of diamondback moth (DBM, Plutella xylostella L.), as judged by the AChE inhibition assay using paraoxon, where the PR strain exhibited ca. 26-fold increased I50 value. Extensive sequence analysis of the previously reported ace2-type DBM AChE gene revealed no difference between the susceptible and PR strains. To elucidate the molecular basis of the prothiofos resistance mechanism mediated by insensitive AChE, we cloned and characterized a second AChE gene from DBM. The deduced amino acid sequence of the novel AChE showed the highest homology to ace1, the second copy of insect ace, and was determined in fact as the predominant AChE in DBM compared to the ace2-type with 13- to 250-fold higher transcription levels depending on different tissues. Sequence comparison of the ace1-type cDNA between the susceptible and PR strains of DBM revealed that a total of three amino acid substitutions are closely associated with the PR strain. Among these, the Gly227Ala mutation, exclusively present in the PR strain, was located at the same position of the organophosphate resistance-conferring Gly-to-Ala mutation on the ace2 of the fruit fly and house fly. This finding suggests that the Gly227Ala mutation along with two other ones on the ace1 are likely responsible for the AChE insensitivity in DBM.
