Journal of Microbiology

Volume 54(10); October 2016

Review

MINIREVIEW] Global transcriptional regulator TrmB family members in prokaryotes: Minwook Kim , Soyoung Park , Sung-Jae Lee; J. Microbiol. 2016;54(10):639-645. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6362-7

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17 Citations

Abstract: Members of the TrmB family act as global transcriptional regulators for the activation or repression of sugar ABC transporters and central sugar metabolic pathways, including glycolytic, gluconeogenic, and other metabolic pathways, and also as chromosomal stabilizers in archaea. As a relatively newly classified transcriptional regulator family, there is limited experimental evidence for their role in Thermococcales, halophilic archaeon Halobacterium salinarum NRC1, and crenarchaea Sulfolobus strains, despite being one of the extending protein families in archaea. Recently, the protein structures of Pyrococcus furiosus TrmB and TrmBL2 were solved, and the transcriptomic data uncovered by microarray and ChIP-Seq were published. In the present review, recent evidence of the functional roles of TrmB family members in archaea is explained and extended to bacteria.

Journal Articles

Diversity and enzyme activity of Penicillium species associated with macroalgae in Jeju Island: Myung Soo Park , Seobihn Lee , Seung-Yoon Oh , Ga Youn Cho , Young Woon Lim; J. Microbiol. 2016;54(10):646-654. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6324-0

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16 Citations

Abstract: A total of 28 strains of 19 Penicillium species were isolated in a survey of extracellular enzyme-producing fungi from macroalgae along the coast of Jeju Island of Korea. Penicillium species were identified based on morphological and β-tubulin sequence analyses. In addition, the halo-tolerance and enzyme activity of all strains were evaluated. The diversity of Penicillium strains isolated from brown algae was higher than the diversity of strains isolated from green and red algae. The commonly isolated species were Penicillium antarcticum, P. bialowiezense, P. brevicompactum, P. crustosum, P. oxalicum, P. rubens, P. sumatrense, and P. terrigenum. While many strains showed endoglucanase, β-glucosidase, and protease activity, no alginase activity was detected. There was a positive correlation between halo-tolerance and endoglucanase activity within Penicillium species. Among 19 Penicillium species, three species–P. kongii, P. olsonii, and P. viticola– have not been previously recorded in Korea.

Arcobacter acticola sp. nov., isolated from seawater on the East Sea in South Korea: Sooyeon Park , Yong-Taek Jung , Sona Kim , Jung-Hoon Yoon; J. Microbiol. 2016;54(10):655-659. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6268-4

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27 Citations

Abstract: A Gram-stain-negative, facultative aerobic, non-flagellated, and rod-shaped bacterium, designated AR-13T, was isolated from a seawater on the East Sea in South Korea, and subjected to a polyphasic taxonomic study. Strain AR-13T grew optimally at 30°C, at pH 7.0–8.0 and in the presence of 0–0.5% (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain AR-13T fell within the clade comprising the type strains of Arcobacter species, clustering coherently with the type strain of Arcobacter venerupis. Strain AR-13T exhibited 16S rRNA gene sequence similarity values of 98.1% to the type strain of A. venerupis and of 93.2–96.9% to the type strains of the other Arcobacter species. Strain AR-13T contained MK-6 as the only menaquinone and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0, C18:1 ω7c, and summed feature 2 (iso-C16:1 I and/or C14:0 3-OH) as the major fatty acids. The major polar lipids detected in strain AR-13T were phosphatidylethanolamine, phosphatidylglycerol, and one unidentified aminophospholipid. The DNA G+C content was 28.3 mol% and its mean DNA-DNA relatedness value with the type strain of A. venerupis was 21%. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain AR-13T is separated from recognized Arcobacter species. On the basis of the data presented, strain AR-13T is considered to represent a novel species of the genus Arcobacter, for which the name Arcobacter acticola sp. nov. is proposed. The type strain is AR-13T (=KCTC 52212T =NBRC 112272T).

RraAS2 requires both scaffold domains of RNase ES for high-affinity binding and inhibitory action on the ribonucleolytic activity: Jihune Heo , Daeyoung Kim , Minju Joo , Boeun Lee , Sojin Seo , Jaejin Lee , Saemee Song , Ji-Hyun Yeom , Nam-Chul Ha , Kangseok Lee; J. Microbiol. 2016;54(10):660-666. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6417-9

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9 Citations

Abstract: RraA is a protein inhibitor of RNase E (Rne), which catalyzes the endoribonucleolytic cleavage of a large proportion of RNAs in Escherichia coli. The antibiotic‐producing bacterium Streptomyces coelicolor also contains homologs of RNase E and RraA, designated as RNase ES (Rns), RraAS1, and RraAS2, respectively. Here, we report that RraAS2 requires both scaffold domains of RNase ES for high-affinity binding and inhibitory action on the ribonucleolytic activity. Analyses of the steady-state level of RNase E substrates indicated that coexpression of RraAS2 in E. coli cells overproducing Rns effectively inhibits the ribonucleolytic activity of full-length RNase ES, but its inhibitory effects were moderate or undetectable on other truncated forms of Rns, in which the N- or/and C-terminal scaffold domain was deleted. In addition, RraAS2 more efficiently inhibited the in vitro ribonucleolytic activity of RNase ES than that of a truncated form containing the catalytic domain only. Coimmunoprecipitation and in vivo cross-linking experiments further showed necessity of both scaffold domains of RNase ES for high-affinity binding of RraAS2 to the enzyme, resulting in decreased RNA-binding capacity of RNase ES. Our results indicate that RraAS2 is a protein inhibitor of RNase ES and provide clues to how this inhibitor affects the ribonucleolytic activity of RNase ES.

Functional analysis of recombinant human and Yarrowia lipolytica O-GlcNAc transferases expressed in Saccharomyces cerevisiae: Hye Ji Oh , Yun Moon , Seon Ah Cheon , Yoonsoo Hahn , Hyun Ah Kang; J. Microbiol. 2016;54(10):667-674. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6401-4

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Abstract: O-linked β-N-acetylglucosamine (O-GlcNAc) glycosylation is an important post-translational modification in many cellular processes. It is mediated by O-GlcNAc transferases (OGTs), which catalyze the addition of O-GlcNAc to serine or threonine residues of the target proteins. In this study, we expressed a putative Yarrowia lipolytica OGT (YlOGT), the only homolog identified in the subphylum Saccharomycotina through bioinformatics analysis, and the human OGT (hOGT) as recombinant proteins in Saccharomyces cerevisiae, and performed their functional characterization. Immunoblotting assays using antibody against O-GlcNAc revealed that recombinant hOGT (rhOGT), but not the recombinant YlOGT (rYlOGT), undergoes auto-O-GlcNAcylation in the heterologous host S. cerevisiae. Moreover, the rhOGT expressed in S. cerevisiae showed a catalytic activity during in vitro assays using casein kinase II substrates, whereas no such activity was obtained in rYlOGT. However, the chimeric human-Y. lipolytica OGT, carrying the human tetratricopeptide repeat (TPR) domain along with the Y. lipolytica catalytic domain (CTD), mediated the transfer of O-GlcNAc moiety during the in vitro assays. Although the overexpression of full-length OGTs inhibited the growth of S. cerevisiae, no such inhibition was obtained upon overexpression of only the CTD fragment, indicating the role of TPR domain in growth inhibition. This is the first report on the functional analysis of the fungal OGT, indicating that the Y. lipolytica OGT retains its catalytic activity, although the physiological role and substrates of YlOGT remain to be elucidated.

Degradation and polymerization of monolignols by Abortiporus biennis, and induction of its degradation with a reducing agent: Chang-Young Hong , Se-Yeong Park , Seon-Hong Kim , Su-Yeon Lee , Won-Sil Choi , In-Gyu Choi; J. Microbiol. 2016;54(10):675-685. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6158-9

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Abstract: This study was carried out to better understand the characteristic modification mechanisms of monolignols by enzyme system of Abortiporus biennis and to induce the degradation of monolignols. Degradation and polymerization of monolignols were simultaneously induced by A. biennis. Whole cells of A. biennis degraded coniferyl alcohol to vanillin and coniferyl aldehyde, and degraded sinapyl alcohol to 2,6-dimethoxybenzene- 1,4-diol, with the production of dimers. The molecular weight of monolignols treated with A. biennis increased drastically. The activities of lignin degrading enzymes were monitored for 24 h to determine whether there was any correlation between monolignol biomodification and ligninolytic enzymes. We concluded that complex enzyme systems were involved in the degradation and polymerization of monolignols. To degrade monolignols, ascorbic acid was added to the culture medium as a reducing agent. In the presence of ascorbic acid, the molecular weight was less increased in the case of coniferyl alcohol, while that of sinapyl alcohol was similar to that of the control. Furthermore, the addition of ascorbic acid led to the production of various degraded compounds: syringaldehyde and acid compounds. Accordingly, these results demonstrated that ascorbic acid prevented the rapid polymerization of monolignols, thus stabilizing radicals generated by enzymes of A. biennis. Thereafter, A. biennis catalyzed the oxidation of stable monolignols. As a result, ascorbic acid facilitated predominantly monolignols degradation by A. biennis through the stabilization of radicals. These findings showed outstanding ability of A. biennis to modify the lignin compounds rapidly and usefully.

Molecular epidemiology of norovirus in asymptomatic food handlers in Busan, Korea, and emergence of genotype GII.17: Hee Soo Koo , Mi Ok Lee , Pyeong Tae Ku , Su Jeong Hwang , Dong Ju Park , Hyung Suk Baik; J. Microbiol. 2016;54(10):686-694. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6312-4

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14 Citations

Abstract: The molecular epidemiology of norovirus infections was studied in food handlers without any symptoms from January to December 2015 in Busan city, Korea. A total of 2,174 fecal specimens from asymptomatic food handlers were analyzed, and 2.3% (49/2,174) were norovirus-positive. Fourteen of 335 samples (4.2%) were positive in January; fifteen of 299 samples (5.0%) in February, and seven of 189 samples (3.7%) in December. However, norovirus was rarely detected in other months. From sequencing analysis, 11 genotypes (five GI and six GII genotypes) were detected. Among the 42 capid gene sequences identified, 14 were from the GI genogroup, while 28 were from the GII genogroup. The most commonly detected genotype was GII.17, comprising 15 (35.7%) of positive samples. From January 2012 to December 2015, 5,138 samples were collected from gastroenteritis patients and outbreaks in Busan. The most detected genotype in 2012, 2013, and 2014 was GII.4 (121, 24, and 12 cases, respectively), but in 2015, GII.17 (25 cases) was the most common. The GII.4 genotype was the major cause of acute gastroenteritis from 2012 to 2014, but the GII.17 genotype became the most prevalent cause in 2015. Continued epidemiological surveillance of GII.17 is needed, together with assessment of the risk of norovirus infection.

MDA7/IL-24 is an anti-viral factor that inhibits influenza virus replication: Rak-Kyun Seong , Young-Ki Choi , Ok Sarah Shin; J. Microbiol. 2016;54(10):695-700. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6383-2

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19 Citations

Abstract: Melanoma differentiation associated gene-7 (mda-7)/interleukin- 24 (IL-24) is a secreted cytokine, which plays an essential role in tumor suppression. Although its role as a multifunctional protein affecting broad types of cancers is well described, functions of IL-24 in host defense against virus infection are yet to be determined. In this study, we explored the anti-viral effect of recombinant IL-24 treatment during influenza infection. Infection of human lung adenocarcinoma cells (A549) with the influenza A virus up-regulated IL-24 mRNA and protein expression in a time-dependent manner. Pre-treatment of A549 cells with recombinant IL-24 protein effectively suppressed viral plaque formation. Furthermore, IL-24 treatment of A549 cells reduced viral non-structural protein 1 (NS1) synthesis, whereas IL-24 knockdown resulted in increased viral replication. Interestingly, IL-24 treatment following influenza A virus infection led to up-regulation of interferon (IFN)-induced antiviral signaling. Taken together, our results suggest that IL-24 exerts a potent suppressive effect on influenza viral replication and can be used in the treatment of influenza infection.

Published Erratum

Erratum] Transcriptional control of sexual development in Cryptococcus neoformans: Mattehew E. Mead , Christina M. Hull; J. Microbiol. 2016;54(10):701-701.; DOI: https://doi.org/10.1007/s12275-016-0648-7

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