Journal of Microbiology

Journal Article

Unexpected Requirement of Small Amino Acids at Position 183 for DNA Binding in the Escherichia coli cAMP Receptor Protein.: Marcus Carranza, Amanda Rea, Daisy Pacheco, Christian Montiel, Jin Park, Hwan Youn; J. Microbiol. 2024;62(10):871-882. Published online September 6, 2024; DOI: https://doi.org/10.1007/s12275-024-00169-2

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Abstract: The Escherichia coli cAMP receptor protein (CRP) relies on the F-helix, the recognition helix of the helix-turn-helix motif, for DNA binding. The importance of the CRP F-helix in DNA binding is well-established, yet there is little information on the roles of its non-base-contacting residues. Here, we show that a CRP F-helix position occupied by a non-base-contacting residue Val183 bears an unexpected importance in DNA binding. Codon randomization and successive in vivo screening selected six amino acids (alanine, cysteine, glycine, serine, threonine, and valine) at CRP position 183 to be compatible with DNA binding. These amino acids are quite different in their amino acid properties (polar, non-polar, hydrophobicity), but one commonality is that they are all relatively small. Larger amino acid substitutions such as histidine, methionine, and tyrosine were made site-directedly and showed to have no detectable DNA binding, further supporting the requirement of small amino acids at CRP position 183. Bioinformatics analysis revealed that small amino acids (92.15% valine and 7.75% alanine) exclusively occupy the position analogous to CRP Val183 in 1,007 core CRP homologs, consistent with our mutant data. However, in extended CRP homologs comprising 3700 proteins, larger amino acids could also occupy the position analogous to CRP Val183 albeit with low occurrence. Another bioinformatics analysis suggested that large amino acids could be tolerated by compensatory small-sized amino acids at their neighboring positions. A full understanding of the unexpected requirement of small amino acids at CRP position 183 for DNA binding entails the verification of the hypothesized compensatory change(s) in CRP.

Review

cAMP Activation of the cAMP Receptor Protein, a Model Bacterial Transcription Factor: Hwan Youn , Marcus Carranza; J. Microbiol. 2023;61(3):277-287. Published online March 9, 2023; DOI: https://doi.org/10.1007/s12275-023-00028-6

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Abstract: The active and inactive structures of the Escherichia coli cAMP receptor protein (CRP), a model bacterial transcr!ption factor, are compared to generate a paradigm in the cAMP-induced activation of CRP. The resulting paradigm is shown to be consistent with numerous biochemical studies of CRP and CRP*, a group of CRP mutants displaying cAMP-free activity. The cAMP affinity of CRP is dictated by two factors: (i) the effectiveness of the cAMP pocket and (ii) the protein equilibrium of apo-CRP. How these two factors interplay in determining the cAMP affinity and cAMP specificity of CRP and CRP* mutants are discussed. Both the current understanding and knowledge gaps of CRP-DNA interactions are also described. This review ends with a list of several important CRP issues that need to be addressed in the future.

Journal Articles

Enhancement of the solubility of recombinant proteins by fusion with a short-disordered peptide: Jun Ren , Suhee Hwang , Junhao Shen , Hyeongwoo Kim , Hyunjoo Kim , Jieun Kim , Soyoung Ahn , Min-gyun Kim , Seung Ho Lee , Dokyun Na; J. Microbiol. 2022;60(9):960-967. Published online July 14, 2022; DOI: https://doi.org/10.1007/s12275-022-2122-z

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Abstract: In protein biotechnology, large soluble fusion partners are widely utilized for increased yield and solubility of recombinant proteins. However, the production of additional large fusion partners poses an additional burden to the host, leading to a decreased protein yield. In this study, we identified two highly disordered short peptides that were able to increase the solubility of an artificially engineered aggregationprone protein, GFP-GFIL4, from 0.6% to 61% (D3-DP00592) and 46% (D4-DP01038) selected from DisProt database. For further confirmation, the peptides were applied to two insoluble E. coli proteins (YagA and YdiU). The peptides also enhanced solubility from 52% to 90% (YagA) and from 27% to 93% (YdiU). Their ability to solubilize recombinant proteins was comparable with strong solubilizing tags, maltosebinding protein (40 kDa) and TrxA (12 kDa), but much smaller (< 7 kDa) in size. For practical application, the two peptides were fused with a restriction enzyme, I-SceI, and they increased I-SceI solubility from 24% up to 75%. The highly disordered peptides did not affect the activity of I-SceI while I-SceI fused with MBP or TrxA displayed no restriction activity. Despite the small size, the highly disordered peptides were able to solubilize recombinant proteins as efficiently as conventional fusion tags and did not interfere with the function of recombinant proteins. Consequently, the identified two highly disordered peptides would have practical utility in protein biotechnology and industry.

[PROTOCOL] High-throughput cultivation based on dilution-to-extinction with catalase supplementation and a case study of cultivating acI bacteria from Lake Soyang: Suhyun Kim , Miri S. Park , Jaeho Song , Ilnam Kang , Jang-Cheon Cho; J. Microbiol. 2020;58(11):893-905. Published online October 30, 2020; DOI: https://doi.org/10.1007/s12275-020-0452-2

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13 Citations

Abstract: Multi-omics approaches, including metagenomics and single- cell amplified genomics, have revolutionized our understanding of the hidden diversity and function of microbes in nature. Even in the omics age, cultivation is an essential discipline in microbial ecology since microbial cultures are necessary to assess the validity of an in silico prediction about the microbial metabolism and to isolate viruses infecting bacteria and archaea. However, the ecophysiological characteristics of predominant freshwater bacterial lineages remain largely unknown due to the scarcity of cultured representatives. In an ongoing effort to cultivate the uncultured majority of freshwater bacteria, the most abundant freshwater Actinobacteria acI clade has recently been cultivated from Lake Soyang through catalase-supplemented high-throughput cultivation based on dilution-to-extinction. This method involves physical isolation of target microbes from mixed populations, culture media simulating natural habitats, and removal of toxic compounds. In this protocol, we describe detailed procedures for isolating freshwater oligotrophic microbes, as well as the essence of the dilution-to-extinction culturing. As a case study employing the catalase-supplemented dilution-to-extinction protocol, we also report a cultivation trial using a water sample collected from Lake Soyang. Of the 480 cultivation wells inoculated with a single lake-water sample, 75 new acI strains belonging to 8 acI tribes (acI-A1, A2, A4, A5, A6, A7, B1, B4, C1, and C2) were cultivated, and each representative strain per subclade could be revived from glycerol stocks. These cultivation results demonstrate that the protocol described in this study is efficient in isolating freshwater bacterioplankton harboring streamlined genomes.

Development of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) thermal inactivation method with preservation of diagnostic sensitivity: Young-Il Kim , Mark Anthony B. Casel , Se-Mi Kim , Seong-Gyu Kim , Su-Jin Park , Eun-Ha Kim , Hye Won Jeong , Haryoung Poo , Young Ki Choi; J. Microbiol. 2020;58(10):886-891. Published online September 29, 2020; DOI: https://doi.org/10.1007/s12275-020-0335-6

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21 Citations

Abstract: Various treatments and agents had been reported to inactivate RNA viruses. Of these, thermal inactivation is generally considered an effective and cheap method of sample preparation for downstream assays. The purpose of this study is to establish a safe inactivation method for SARS-CoV-2 without compromising the amount of amplifiable viral genome necessary for clinical diagnoses. In this study, we demonstrate the infectivity and genomic stability of SARSCoV- 2 by thermal inactivation at both 56°C and 65°C. The
results
substantiate that viable SARS-CoV-2 is readily inactivated when incubated at 56°C for 30 min or at 65°C for 10 min. qRT-PCR of specimens heat-inactivated at 56°C for 30 min or 65°C for 15 min revealed similar genomic RNA stability compared with non-heat inactivated specimens. Further, we demonstrate that 30 min of thermal inactivation at 56°C could inactivate viable viruses from clinical COVID-19 specimens without attenuating the qRT-PCR diagnostic sensitivity. Heat treatment of clinical specimens from COVID-19 patients at 56°C for 30 min or 65°C for 15 min could be a useful
method
for the inactivation of a highly contagious agent, SARS-CoV-2. Use of this method would reduce the potential for secondary infections in BSL2 conditions during diagnostic procedures. Importantly, infectious virus can be inactivated in clinical specimens without compromising the sensitivity of the diagnostic RT-PCR assay.

Partial characteristics of hemolytic factors secreted from airborne Aspergillus and Penicillium, and an enhancement of hemolysis by Aspergillus micronesiensis CAMP-like factor via Staphylococcus aureus-sphingomyelinase: Sumonrat Kaveemongkonrat , Kwanjit Duangsonk , Jos Houbraken , Phimchat Suwannaphong , Nongnuch Vanittanakom Vanittanakom , Malee Mekaprateep; J. Microbiol. 2019;57(12):1086-1094. Published online November 4, 2019; DOI: https://doi.org/10.1007/s12275-019-9133-4

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Abstract: One of the advantages for initial survival of inhaled fungal spores in the respiratory tract is the ability for iron acquisition via hemolytic factor-production. To examine the ability of indoor Aspergillus and Penicillium affecting hemolysis, the secreted factors during the growth of thirteen strains from eight species were characterized in vitro for their hemolytic activity (HA) and CAMP-like reaction. The hemolytic index of HA on human blood agar of Aspergillus micronesiensis, Aspergillus wentii, Aspergillus westerdijkiae, Penicillium citrinum, Penicillium copticola, Penicillium paxilli, Penicillium steckii, and Penicillium sumatrense were 1.72 ± 0.34, 1.61 ± 0.41, 1.69 ± 0.16, 1.58 ± 0.46, 3.10 ± 0.51, 1.22 ± 0.19, 2.55 ± 0.22, and 1.90 ± 0.14, respectively. The secreted factors of an Aspergillus wentii showed high HA when grown in undernourished broth at 25°C at an exponential phase and were heat sensitive. Its secreted proteins have an estimated relative molecular weight over 50 kDa. Whereas, the factors of Penicillium steckii were secreted in a similar condition at a late exponential phase but showed low HA and heat tolerance. In a CAMP-like test with sheep blood, the synergistic hemolytic reactions between most tested mold strains and Staphylococcus aureus were identified. Moreover, the enhancement of α-hemolysis of Staphylococcus aureus could occur through the interaction of Staphylococcus aureus-sphingomyelinase and CAMP-like factors secreted from Aspergillus micronesiensis. Further studies on the characterization of purified hemolytic- and CAMP-like-factors secreted from Aspergillus wentii and Aspergillus micronesiensis may lead to more understanding of their involvement of hemolysis

Arthrobacter dokdonellae sp. nov., isolated from a plant of the genus Campanula: Hyeon-Woo Koh , Myung-Suk Kang , Ki-Eun Lee , Eun-Young Lee , Hongik Kim , Soo-Je Park; J. Microbiol. 2019;57(9):732-737. Published online May 11, 2019; DOI: https://doi.org/10.1007/s12275-019-8540-x

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Abstract: A Gram-stain-positive, oxidase- and catalase-positive, motile, aerobic, and rod-shaped bacterial strain, designated as DCT-5T, was isolated from a native plant belonging to the genus Campanula at Dokdo island, Republic of Korea. Growth of the strain DCT-5T was observed at 15–37°C (optimum 30°C) on R2A broth, pH 6.0–8.0 (optimum 7.0), and 0–5% (w/v) NaCl concentration (optimum 0%). The 16S rRNA gene sequence analysis revealed that strain DCT-5T was most closely related to Arthrobacter silviterrae KIS14-16T, Arthrobacter livingstonensis LI2T, Arthrobacter stackebrandtii CCM 2783T, Arthrobacter cryoconiti Cr6-08T, Arthrobacter ramosus CCM 1646T, and Arthrobacter psychrochitiniphilus GP3T with pairwise sequence similarities of 98.76%, 97.47%, 97.25%, 97.11%, 97.11%, and 97.00%, respectively. The DNA G+C content of strain DCT-5T was 64.7 mol%, and its DNA–DNA relatedness values with A. silviterrae KIS14-16T, A. livingstonensis LI2T, A. stackebrandtii CCM 2783T, A. psychrochitiniphilus GP3T, A. ramosus CCM 1646T, and A. cryoconiti Cr6-08T were 32.57 ± 2.02%, 28.75 ± 0.88%, 31.93 ± 1.15%, 34.73 ± 1.86%, 29.12 ± 1.56%, and 27.23 ± 0.88%, respectively. The major quinone was MK-9(H2) and major fatty acids were anteiso-C15:0, anteiso-C17:0, iso-C15:0, and iso-C16:0. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylinositol (PI), unidentified glycolipid (GL), two unidentified aminophospholipids (APLs), and three unidentified lipids (Ls). The peptidoglycan type was A3α. On the basis of phenotypic, phylogenetic, genotypic, and chemotaxonomic characteristics, strain DCT-5T represents a novel species of the genus Arthrobacter, for which the name Arthrobacter dokdonellae sp. nov. is proposed. The type strain is DCT-5T (= KCTC 49189T = LMG 31284T).

Role of putative virulence traits of Campylobacter jejuni in regulating differential host immune responses: Ankita Singh , Amirul Islam Mallick; J. Microbiol. 2019;57(4):298-309. Published online February 22, 2019; DOI: https://doi.org/10.1007/s12275-019-8165-0

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16 Citations

Abstract: Among the major enteric pathogens, Campylobacter jejuni is considered an important source of diarrheal illness in humans. In contrast to the acute gastroenteritis in humans, C. jejuni exhibits prolonged cecal colonization at a high level with little or no pathology in chickens. Although several known virulence determinants of C. jejuni have been found to be associated with a higher degree of pathogenesis in humans, to date, little is known about their functions in the persistent colonization of chickens. The present study was undertaken to assess the role of C. jejuni in imparting differential host immune responses in human and chicken cells. Based on the abundance of major genes encoding virulence factors (GEVFs), we used a particular isolate that harbors the cadF, flaA, peb1, racR, ciaB, cdtB, and hcp genes. This study showed that hypervirulent C. jejuni isolate that encodes a functional type VI secretion system (T6SS) has a greater ability to invade and create characteristic “attaching and effacing” lesions in human INT407 compared to primary chicken embryo intestinal cells (CEICs). Furthermore, we demonstrated that the higher bacterial invasion in human INT407 triggered higher levels of expression of major proinflammatory cytokines, such as IL- 1β and IL-6, and significant downregulation of IL-17A gene expression (P ≤ 0.05). The findings of the present study suggest that the enhanced ability of C. jejuni to invade human cells is tightly regulated by proinflammatory cytokines in the gut and possibly holds the keys to the observed differences in pathogenesis between human and chicken cells.

Paraburkholderia dokdonella sp. nov., isolated from a plant from the genus Campanula: Man-Young Jung , Myung-Suk Kang , Ki-Eun Lee , Eun-Young Lee , Soo-Je Park; J. Microbiol. 2019;57(2):107-112. Published online November 19, 2018; DOI: https://doi.org/10.1007/s12275-019-8500-5

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9 Citations

Abstract: The novel Gram-stain-negative, rod-shaped, aerobic bacterial strain DCR-13T was isolated from a native plant belonging to the genus Campanula on Dokdo, an island in the Republic of Korea. Comparative analysis of the 16S rRNA gene sequence indicated that this strain is closely related to Paraburkholderia peleae PP52-1T (98.43% 16S rRNA gene sequence similarity), Paraburkholderia oxyphila NBRC 105797T (98.42%), Paraburkholderia sacchari IPT 101T (98.28%), Paraburkholderia mimosarum NBRC 106338T (97.80%), Paraburkholderia denitrificans KIS30-44T (97.46%), and Paraburkholderia paradise WAT (97.45%). This analysis of the 16S rRNA gene sequence also suggested that DCR-13T and the six closely related strains formed a clade within the genus Paraburkholderia, but that DCR-13T was clearly separated from the established species. DCR-13T had ubiquinone 8 as its predominant respiratory quinone, and its genomic DNA G + C content was 63.9 mol%. The isolated strain grew at a pH of 6.0–8.0 (with an optimal pH of 6.5), 0–4% w/v NaCl (with an optimal level of 0%), and a temperature of 18–42°C (with an optimal temperature of 30°C). The predominant fatty acids were C16:0, summed feature 8 (C18:1 ω7c/C18:1 ω6c), C17:0 cyclo, C19:0 cyclo ω8c, summed feature 3 (C16:1 ω6c/C16:1 ω7c) and summed feature 2 (C12:0 aldehyde), and the major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. On the basis of polyphasic evidence, it is proposed that strain DCR-13T (= KCTC 62811T = LMG 30889T) represents the type strain of a novel species, Paraburkholderia dokdonella sp. nov.

Paenibacillus seodonensis sp. nov., isolated from a plant of the genus Campanula: Myung-Suk Kang , Ki-Eun Lee , Eun-Young Lee , Soo-Je Park; J. Microbiol. 2018;56(12):874-879. Published online October 25, 2018; DOI: https://doi.org/10.1007/s12275-018-8455-y

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Abstract: Strain DCT-19T, representing a Gram-stain-positive, rodshaped, aerobic bacterium, was isolated from a native plant belonging to the genus Campanula on Dokdo, the Republic of Korea. Comparative analysis of the 16S rRNA gene sequence showed that this strain was closely related to Paenibacillus amylolyticus NRRL NRS-290T (98.6%, 16S rRNA gene sequence similarity), Paenibacillus tundrae A10bT (98.1%), and Paenibacillus xylanexedens NRRL B-51090T (97.6%). DNADNA hybridization indicated that this strain had relatively low levels of DNA-DNA relatedness with P. amylolyticus NRRL NRS-290T (30.0%), P. xylanexedens NRRL B-51090T (29.0%), and P. tundrae A10bT (24.5%). Additionally, the genomic DNA G + C content of DCT-19T was 44.8%. The isolated strain grew at pH 6.0–8.0 (optimum, pH 7.0), 0–4% (w/v) NaCl (optimum, 0%), and a temperature of 15–45°C (optimum 25–30°C). The sole respiratory quinone in the strain was menaquinone-7, and the predominant fatty acids were C15:0 anteiso, C16:0 iso, and C16:0. In addition, the major polar lipids were diphosphatidylglycerol and phosphatidylethanolamine. Based on its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain DCT-19T is proposed as a novel species in the genus Paenibacillus, for which the name Paenibacillus seodonensis sp. nov. is proposed (=KCTC 43009T =LMG 30888T). The type strain of Paenibacillus seodonensis is DCT-19T.

De novo transcriptome assembly and characterization of the 10-hydroxycamptothecin-producing Xylaria sp. M71 following salicylic acid treatment: Xiaowei Ding , Kaihui Liu , Yonggui Zhang , Feihu Liu; J. Microbiol. 2017;55(11):871-876. Published online October 27, 2017; DOI: https://doi.org/10.1007/s12275-017-7173-1

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Abstract: In the present study, we identified genes that are putatively involved in the production of fungal 10-hydroxycamptothecin via transcriptome sequencing and characterization of the Xylaria sp. M71 treated with salicylic acid (SA). A total of 60,664,200 raw reads were assembled into 26,044 unigenes. BLAST assigned 8,767 (33.7%) and 10,840 (41.6%) unigenes to 40 Gene Ontology (GO) annotations and 108 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, respectively. A total of 3,713 unigenes comprising 1,504 upregulated and 2,209 downregulated unigenes were found to be differentially expressed between SA-induced and control fungi. Based on the camptothecin biosynthesis pathway in plants, 13 functional genes of Xylaria sp. M71 were mapped to the mevalonate (MVA) pathway, suggesting that the fungal 10-hydroxycamptothecin is produced via the MVA pathway. In summary, analysis of the Xylaria sp. M71 transcriptome allowed the identification of unigenes that are putatively involved in 10-hydroxycamptothecin biosynthesis in fungi.

Epidemiological relationships of Campylobacter jejuni strains isolated from humans and chickens in South Korea: Jae-Young Oh , Yong-Kuk Kwon , Bai Wei , Hyung-Kwan Jang , Suk-Kyung Lim , Cheon-Hyeon Kim , Suk-Chan Jung , Min-Su Kang; J. Microbiol. 2017;55(1):13-20. Published online December 30, 2016; DOI: https://doi.org/10.1007/s12275-017-6308-8

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Abstract: Thirty-nine human isolates of Campylobacter jejuni obtained from a national university hospital during 2007–2010 and 38 chicken isolates of C. jejuni were collected from poultry farms during 2009–2010 in South Korea were used in this study. Campylobacter genomic species and virulence-associated genes were identified by PCR. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed to compare their genetic relationships. All isolates were highly resistant to ciprofloxacin, nalidixic acid, and tetracycline. Of all isolates tested, over 94% contained seven virulence associated genes (flaA, cadF, racR, dnaJ, cdtA, cdtB, and cdtC). All isolates were classified into 39 types by PFGE clustering with 90% similarity. Some chicken isolates were incorporated into some PFGE types of human isolates. MLST analysis for the 39 human isolates and 38 chicken isolates
result
ed in 14 and 23 sequence types (STs), respectively, of which 10 STs were new. STs overlapped in both chicken and human isolates included ST-21, ST-48, ST-50, ST-51, and ST-354, of which ST-21 was the predominant ST in both human and chicken isolates. Through combined analysis of PFGE types and STs, three chicken isolates were clonally related to the three human isolates associated with food poisoning (VII-ST-48, XXII-ST-354, and XXVIII-ST-51). They were derived from geographically same or distinct districts. Remarkably, clonal spread of food poisoning pathogens between animals and humans was confirmed by population genetic analysis. Consequently, contamination of campylobacters with quinolone resistance and potential virulence genes in poultry production and consumption may increase the risk of infections in humans.

Reviews

MINIREVIEW] Clinical relevance of infections with zoonotic and human oral species of Campylobacter: Soomin Lee , Jeeyeon Lee , Jimyeong Ha , Yukyung Choi , Sejeong Kim , Heeyoung Lee , Yohan Yoon , Kyoung-Hee Choi; J. Microbiol. 2016;54(7):459-467. Published online June 28, 2016; DOI: https://doi.org/10.1007/s12275-016-6254-x

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35 Citations

Abstract: Genus Campylobacter has been recognized as a causative bacterial agent of animal and human diseases. Human Campylobacter infections have caused more concern. Campylobacters can be classified into two groups in terms of their original host: zoonotic and human oral species. The major zoonotic species are Campylobacter jejuni and Campylobacter coli, which mostly reside in the intestines of avian species and are transmitted to humans via consumption of contaminated poultry products, thus causing human gastroenteritis and other diseases as sequelae. The other campylobacters, human oral species, include C. concisus, C. showae, C. gracilis, C. ureolyticus, C. curvus, and C. rectus. These species are isolated from the oral cavity, natural colonization site, but have potential clinical relevance in the periodontal region to varying extent. Two species, C. jejuni and C. coli, are believed to be mainly associated with intestinal diseases, but recent studies suggested that oral Campylobacter species also play a significant role in intestinal diseases. This review offers an outline of the two Campylobacter groups (zoonotic and human oral), their virulence traits, and the associated illnesses including gastroenteritis.

MINIREVIEW] The cAMP/protein kinase A signaling pathway in pathogenic basidiomycete fungi: Connections with iron homeostasis: Jaehyuk Choi , Won Hee Jung , James W. Kronstad; J. Microbiol. 2015;53(9):579-587. Published online August 1, 2015; DOI: https://doi.org/10.1007/s12275-015-5247-5

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Abstract: A number of pathogenic species of basidiomycete fungi are either life-threatening pathogens of humans or major economic pests for crop production. Sensing the host is a key aspect of pathogen proliferation during disease, and signal transduction pathways are critically important for detecting environmental conditions and facilitating adaptation. This review focuses on the contributions of the cAMP/protein kinase A (PKA) signaling pathway in Cryptococcus neoformans, a species that causes meningitis in humans, and Ustilago maydis, a model phytopathogen that causes a smut disease on maize. Environmental sensing by the cAMP/PKA pathway regulates the production of key virulence traits in C. neoformans including the polysaccharide capsule and melanin. For U. maydis, the pathway controls the dimorphic transition from budding growth to the filamentous cell type required for proliferation in plant tissue. We discuss recent advances in identifying new components of the cAMP/PKA pathway in these pathogens and highlight an emerging theme that pathway signaling influences iron acquisition.

Research Support, Non-U.S. Gov't

Expression of Escherichia coli DcuS-R Two-Component Regulatory System is Regulated by the Secondary Internal Promoter Which is Activated by CRP-cAMP: Tomoya Oyamada , Katsushi Yokoyama , Michiko Morinaga , Masashi Suzuki , Kozo Makino; J. Microbiol. 2007;45(3):234-240.; DOI: https://doi.org/2537 [pii]

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Abstract: The DcuS-R two-component system of Escherichia coli senses C4-dicarboxylates of the medium and regulates expression of the genes related to utilization of them. It is known that phospho-DcuR induces expression of genes such as the dcuB-fumB operon, the frdABCD operon, and the dctA gene. We analyzed promoters of the dcuS-R operon to elucidate the transcriptional regulation system. We found a novel internal promoter within the dcuS gene that is regulated by the transcriptional regulator, CRP-cAMP, in both aerobic and anaerobic conditions.

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