• Journal of Microbiology and Biotechnology
• /
• v.15 no.3
• /
• pp.656-659
• /
• 2005

Small peptides synthesized by nonribosomal peptide synthetases (NRPSs) genes are found in bacteria and fungi. While some microbial taxa have few, others make a large number and variety. However, biochemical characterization of the products synthesized by NPRS demands a great deal of efforts. Since the completion of genome projects of numerous microorganisms, the numbers of available NRPSs genes are being expanded. Prediction of the peptides encoded by NRPS could save time and efforts. We chose the NRPS gene from Bradyrhizobium japonicum as a model to predict the peptide structure encoded by NRPS genes. Using computational analyses, the domain structure of this gene was defined, and the structure of a peptide synthesized by this NRPS was deduced. It was found that it encoded a tripeptide consisting of proline-serine-phenylalanine. This method would be helpful to predict the structure of small peptides with various NPRS genes from the genome sequence.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.3
• /
• pp.439-449
• /
• 2017

Beauveria bassiana infects a number of pest species and is known to produce insecticidal substances, such as the nonribosomal peptides (NRPs) beauvericin and bassianolide. However, most NRPs and their biological roles in B. bassiana remain undiscovered. To identify NRPs that potentially contribute to pathogenesis, the 21 predicted NRP synthetases (NRPSs) or NRPS-like proteins of B. bassiana ARSEF 2860 were primarily ranked into three functional groups: basic metabolism (7 NRPSs), pathogenicity (12 NRPSs), and unknown function (2 NRPSs). Based on the transcript levels during in vivo growth on diamondback moth (Plutella xylostella (Linnaeus)), half of the Group II NRPSs were likely to be involved in infection. Given that the metabolites biosynthesized by these NRPSs remain to be determined, our result underlines the importance of the NRPSome in fungal pathogenesis, and will serve as a guide for future genomic mining projects to discover functionally essential and structurally diverse NRPs in fungal genomes.

• The Plant Pathology Journal
• /
• v.40 no.3
• /
• pp.322-328
• /
• 2024

Soybean (Glycine max), a crucial global crop, experiences yearly yield reduction due to diseases such as anthracnose (Colletotrichum truncatum) and root rot (Fusarium spp.). The use of fungicides, which have traditionally been employed to control these phytopathogens, is now facing challenges due to the emergence of fungicide-resistant strains. Streptomyces bacillaris S8 strain S8 is previously known to produce valinomycin t through a nonribosomal peptide synthetase (NRPS) pathway. The objective of this study was to evaluate the antifungal activity of S. bacillaris S8 against C. truncatum and Fusarium sp., assessing its efficacy against soybean pathogens. The results indicate that strain S8 effectively controlled both above-ground and underground soybean diseases, using the NRPS and NRPS-related compound, suggesting its potential as a biological control in plant-microbe interactions. These findings underscore the pivotal role of the stain S8 in fostering healthy soybean microbial communities and emphasize the significance of microbiota structure studies in unveiling potent biocontrol agents.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.8
• /
• pp.4086-4092
• /
• 2013

Mycosporine-like amino acids (MAAs) are UV-absorbing substances, and diverse marine organisms have the evolved the capacity to diminished the direct and indirect damaging effects of environmental ultraviolet radiation by synthesis and accumulation of MAAs. In this study, we manufactured a radiofrequency (RF) generation device and applied to microalgal culture. $0.35{\pm}0.05$ mHz of RF was supplied to culture vessel for Chlamydomonas sp. and samples were harvested at the designated time intervals (1, 0.5, 1 and 2 hr). MAAs biosynthetic genes, dehydroquinate synthase homolog (DHQS-like) and nonribosomal peptide synthetase homolog (NRPS-like), were cloned from Chlamydomonas sp. and their gene expressions under the RF exposure were analyzed using qRT-PCR. DHQS-like and NRPS-like gene expressions of Chlamydomonas sp. exposed to RF were increased 1.46 and 1.19 fold at 1 hr, respectively. These results means that DHQS-like and NRPS-like genes can be good biomarker candidates for diagnosis of MAAs biosynthesis in the Chlamydomonas sp.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.3
• /
• pp.229-237
• /
• 2009

Among 12 marine bacterial strains from the China coast that exhibited interesting bioactivity (positive for both antimicrobial and cytotoxic activities), only four strains, namely, NJ6-3-1, NJ6-3-2, NB-6, and YTHM-17, had a KS domain or A domain when screened for PKS and NRPS genes using a PCR. Interestingly, two of these strains belonging to Pseudoalteromonas and associated with the marine sponge Hymeniacidon perleve were positive for both PKS and NRPS, whereas the other two strains of Pseudoalteromonas did not have a PKS or NRPS gene. A molecular phylogeny analysis and DGGE analysis of the Pseudoalteromonas sp. indicated that they had a specific affinity with the host marine sponge Hymeniacidon perleve. Furthermore, an analysis of a partial sequence of Pseudoalteromonas sp. NJ6-3-2 isolated from the marine sponge Hymeniacidon perleve obtained from genomic walking using a computational approach indicated a relatively complete PKS module including auxiliary domains (DH, KR, and Cy).

• Journal of Applied Biological Chemistry
• /
• v.65 no.3
• /
• pp.159-166
• /
• 2022

Epicoccum nigrum produces epipyrone A (orevactaene), a yellow polyketide pigment. Its biosynthetic gene cluster was previously characterized in E. nigrum KACC 40642. The YES liquid culture of this strain revealed high-level production of epicoccamide (EPC), with an identity that was determined using liquid chromatography-mass spectrometry analysis and molecular mass search using the SuperNatural database V2 webserver. The production of EPC was further confirmed by compound isolation and nuclear magnetic resonance spectroscopy. EPC is a highly reduced polyketide with tetramic acid and mannosyl moieties. The EPC structure guided us to localize the hypothetical EPC biosynthetic gene cluster (BGC) in E. nigrum ICMP 19927 genome sequence. The BGC contains genes encoding highly reducing (HR)-fungal polyketide synthase (fPKS)-nonribosomal peptide synthetase (NRPS), glycosyltransferase (GT), enoylreductase, cytochrome P450, and N-methyltrasnferase. Targeted inactivation of the HR-fPKS-NRPS and GT genes abolished EPC production, supporting the successful localization of EPC BGC. This study provides a platform to explore the hidden biological activities of EPC, a bolaamphiphilic compound.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.4
• /
• pp.359-365
• /
• 2011

Cyanobacterial strains of the genus Spirulina have recently been identified as an excellent source of sulfolipids, some of which possess anti-HIV properties. Thus, to investigate the distribution of sufolipid biosynthesis pathways in Spirulina, a genetic screening/phylogentic study was performed. Five different strains of Spirulina [Spirulina (Jiangmen), Spirulina sp., S. platensis, S. maxima, and Spirulina seawater] sourced from different locations were initially classified via 16S rDNA sequencing, and then screened for the presence of the sulfolipid biosynthesis genes sqdB and sqdX via a PCR. To assess the suitability of these strains for human consumption and safe therapeutic use, the strains were also screened for the presence of genes encoding nonribosomal peptide synthases (NRPSs) and polyketide synthases (PKSs), which are often associated with toxin pathways in cyanobacteria. The results of the 16S rDNA analysis and phylogenetic study indicated that Spirulina sp. is closely related to Halospirulina, whereas the other four Spirulina strains are closely related to Arthrospira. Homologs of sqdB and sqdX were identified in Spirulina (Jiangmen), Spirulina sp., S. platensis, and the Spirulina seawater. None of the Spirulina strains screened in this study tested positive for NRPS or PKS genes, suggesting that these strains do not produce NRP or PK toxins.

• The Plant Pathology Journal
• /
• v.34 no.4
• /
• pp.327-334
• /
• 2018

Northern corn leaf spot and southern corn leaf blight caused by Cochliobolus carbonum (anamorph, Bipolaris zeicola) and Cochliobolus heterostrophus (anamorph, Bipolaris maydis), respectively, are common maize diseases in Korea. Accurate detection of plant pathogens is necessary for effective disease management. Based on the polyketide synthase gene (PKS) of Cochliobolus carbonum and the nonribosomal peptide synthetase gene (NRPS) of Cochliobolus heterostrophus, primer pairs were designed for PCR to simultaneously detect the two fungal pathogens and were specific and sensitive enough to be used for duplex PCR analysis. This duplex PCR-based method was found to be effective for diagnosing simultaneous infections from the two Cochliobolus species that display similar morphological and mycological characteristics. With this method, it is possible to prevent infections in maize by detecting infected seeds or maize and discarding them. Besides saving time and effort, early diagnosis can help to prevent infections, establish comprehensive management systems, and secure healthy seeds.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.3
• /
• pp.427-433
• /
• 2008

The cephabacins produced by Lysobacter lactamgenus are ${\beta}$-lactam antibiotics composed of a cephem nucleus, an acetate residue, and an oligopeptide side chain. In order to understand the precise implication of the polyketide synthase (PKS) module in the biosynthesis of cephabacin, the genes for its core domains, ${\beta}$-ketoacyl synthase (KS), acyltransferase (AT), and acyl carrier protein (ACP), were amplified and cloned into the pET-32b(+) expression vector. The sfp gene encoding a protein that can modify apo-ACP to its active holo-form was also amplified. The recombinant KS, AT, apo-ACP, and Sfp overproduced in the form of $His_6$-tagged fusion proteins in E. coli BL21(DE3) were purified by nickel-affinity chromatography. Formation of stable peptidyl-S-KS was observed by in vitro acylation of the KS domain with the substrate [L-Ala-L-Ala-L-Ala-L-$^3H$-Arg] tetrapeptide-S-N-acetylcysteamine, which is the evidence for the selective recognition of tetrapeptide produced by nonribosomal peptide synthetase (NRPS) in the NRPS/PKS hybrid. In order to confirm whether malonyl CoA is the extender unit for acetylation of the peptidyl moiety, the AT domain, ACP domain, and Sfp protein were treated with $^{14}C$-malonyl-CoA. The results clearly show that the AT domain is able to recognize the extender unit and decarboxylatively acetylated for the elongation of the tetrapeptide. However, the transfer of the activated acetyl group to the ACP domain was not observed, probably attributed to the improper capability of Sfp to activate apo-ACP to the holo-ACP form.