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The elicitin-like glycoprotein, ELI025, is secreted by the pathogenic oomycete Pythium insidiosum and evades host antibody responses.

Lerksuthirat T, Lohnoo T, Inkomlue R, Rujirawat T, Yingyong W, Khositnithikul R, Phaonakrop N, Roytrakul S, Sullivan TD, Krajaejun T - PLoS ONE (2015)

Bottom Line: Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species.In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses.ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand.

ABSTRACT
Pythium insidiosum is a unique oomycete that can infect humans and animals. Patients with a P. insidiosum infection (pythiosis) have high rates of morbidity and mortality. The pathogen resists conventional antifungal drugs. Information on the biology and pathogenesis of P. insidiosum is limited. Many pathogens secrete proteins, known as effectors, which can affect the host response and promote the infection process. Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species. In plant-pathogenic oomycetes, elicitins function as pathogen-associated molecular pattern molecules, sterol carriers, and plant defense stimulators. Recently, we reported a number of elicitin-encoding genes from the P. insidiosum transcriptome. The function of elicitins during human infections is unknown. One of the P. insidiosum elicitin-encoding genes, ELI025, is highly expressed and up-regulated at body temperature. This study aims to characterize the biochemical, immunological, and genetic properties of the elicitin protein, ELI025. A 12.4-kDa recombinant ELI025 protein (rELI025) was expressed in Escherichia coli. Rabbit anti-rELI025 antibodies reacted strongly with the native ELI025 in P. insidiosum's culture medium. The detected ELI025 had two isoforms: glycosylated and non-glycosylated. ELI025 was not immunoreactive with sera from pythiosis patients. The region near the transcriptional start site of ELI025 contained conserved oomycete core promoter elements. In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses. ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis.

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Sequence alignment of core promoter regions of the P. insidiosum ELI025 gene and various genes from several oomycetes and parasites.The ELI025 sequences (accession number AB971191–3), used for the alignment, are derived from three different P. insidiosum strains. Conserved nucleotides are highlighted in grey. The underlined letters indicate the known transcriptional start site, and is indicated below as "+1". Two putative core promoter components, an initiator element (Inr; 5’-TCATTCC-3’; positions-2 to +5) and a flanking promoter region (FPR; 5’-CAACCTTCC-3’; positions +7 to +15), are found in the upstream region of all genes. (Abbreviation: NCBI, National Center for Biotechnology Information).
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pone.0118547.g002: Sequence alignment of core promoter regions of the P. insidiosum ELI025 gene and various genes from several oomycetes and parasites.The ELI025 sequences (accession number AB971191–3), used for the alignment, are derived from three different P. insidiosum strains. Conserved nucleotides are highlighted in grey. The underlined letters indicate the known transcriptional start site, and is indicated below as "+1". Two putative core promoter components, an initiator element (Inr; 5’-TCATTCC-3’; positions-2 to +5) and a flanking promoter region (FPR; 5’-CAACCTTCC-3’; positions +7 to +15), are found in the upstream region of all genes. (Abbreviation: NCBI, National Center for Biotechnology Information).

Mentions: The 5'-untranslated and -flanking DNA sequences of the ELI025 gene from the three P. insidiosum strains were compared with that of various genes from several oomycetes and parasites (Fig. 2). These sequences share a 19-nucleotide oomycete core-promoter sequence, located between 9 and 79 nucleotides upstream of the start codon (Fig. 2). Two putative core-promoter components, an initiator element (Inr; 5’-TCATTCC-3’) and a flanking promoter region (FPR; 5’-CAACCTTCC-3’), were identified in this region of ELI025 (Fig. 2). A predicted transcription start site (+1; Fig. 2) of the ELI025 gene is within the Inr element. A TATA box was not observed in the promoter region of ELI025.


The elicitin-like glycoprotein, ELI025, is secreted by the pathogenic oomycete Pythium insidiosum and evades host antibody responses.

Lerksuthirat T, Lohnoo T, Inkomlue R, Rujirawat T, Yingyong W, Khositnithikul R, Phaonakrop N, Roytrakul S, Sullivan TD, Krajaejun T - PLoS ONE (2015)

Sequence alignment of core promoter regions of the P. insidiosum ELI025 gene and various genes from several oomycetes and parasites.The ELI025 sequences (accession number AB971191–3), used for the alignment, are derived from three different P. insidiosum strains. Conserved nucleotides are highlighted in grey. The underlined letters indicate the known transcriptional start site, and is indicated below as "+1". Two putative core promoter components, an initiator element (Inr; 5’-TCATTCC-3’; positions-2 to +5) and a flanking promoter region (FPR; 5’-CAACCTTCC-3’; positions +7 to +15), are found in the upstream region of all genes. (Abbreviation: NCBI, National Center for Biotechnology Information).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4368664&req=5

pone.0118547.g002: Sequence alignment of core promoter regions of the P. insidiosum ELI025 gene and various genes from several oomycetes and parasites.The ELI025 sequences (accession number AB971191–3), used for the alignment, are derived from three different P. insidiosum strains. Conserved nucleotides are highlighted in grey. The underlined letters indicate the known transcriptional start site, and is indicated below as "+1". Two putative core promoter components, an initiator element (Inr; 5’-TCATTCC-3’; positions-2 to +5) and a flanking promoter region (FPR; 5’-CAACCTTCC-3’; positions +7 to +15), are found in the upstream region of all genes. (Abbreviation: NCBI, National Center for Biotechnology Information).
Mentions: The 5'-untranslated and -flanking DNA sequences of the ELI025 gene from the three P. insidiosum strains were compared with that of various genes from several oomycetes and parasites (Fig. 2). These sequences share a 19-nucleotide oomycete core-promoter sequence, located between 9 and 79 nucleotides upstream of the start codon (Fig. 2). Two putative core-promoter components, an initiator element (Inr; 5’-TCATTCC-3’) and a flanking promoter region (FPR; 5’-CAACCTTCC-3’), were identified in this region of ELI025 (Fig. 2). A predicted transcription start site (+1; Fig. 2) of the ELI025 gene is within the Inr element. A TATA box was not observed in the promoter region of ELI025.

Bottom Line: Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species.In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses.ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand.

ABSTRACT
Pythium insidiosum is a unique oomycete that can infect humans and animals. Patients with a P. insidiosum infection (pythiosis) have high rates of morbidity and mortality. The pathogen resists conventional antifungal drugs. Information on the biology and pathogenesis of P. insidiosum is limited. Many pathogens secrete proteins, known as effectors, which can affect the host response and promote the infection process. Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species. In plant-pathogenic oomycetes, elicitins function as pathogen-associated molecular pattern molecules, sterol carriers, and plant defense stimulators. Recently, we reported a number of elicitin-encoding genes from the P. insidiosum transcriptome. The function of elicitins during human infections is unknown. One of the P. insidiosum elicitin-encoding genes, ELI025, is highly expressed and up-regulated at body temperature. This study aims to characterize the biochemical, immunological, and genetic properties of the elicitin protein, ELI025. A 12.4-kDa recombinant ELI025 protein (rELI025) was expressed in Escherichia coli. Rabbit anti-rELI025 antibodies reacted strongly with the native ELI025 in P. insidiosum's culture medium. The detected ELI025 had two isoforms: glycosylated and non-glycosylated. ELI025 was not immunoreactive with sera from pythiosis patients. The region near the transcriptional start site of ELI025 contained conserved oomycete core promoter elements. In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses. ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis.

Show MeSH
Related in: MedlinePlus