Dataset Information

Recombinant AfusinC, an anionic fungal CS?? defensin from Aspergillus fumigatus, exhibits antimicrobial activity against gram-positive bacteria.

ABSTRACT: Antimicrobial peptides (AMPs) are short and generally positively charged peptides found in a wide variety of organisms. CS?? defensins are a group of AMPs. These defensins are composed of an ?-helix and a ?-sheet linked by three or four disulphide bridges. In this study, we describe the antimicrobial activity of an anionic CS?? fungal defensin from Aspergillus fumigatus, AfusinC. AfusinC was recombinantly produced as a fusion protein in Escherichia coli. The tag was removed by proteolytic cleavage, and AfusinC was purified by size exclusion chromatography. About 0.8 mg of recombinant AfusinC was obtained from 1 L of culture. Recombinant AfusinC was active against mainly gram-positive bacteria including human pathogens and a multiresistant-strain of A. aureus. Additionally, AfusinC showed bactericidal effect against Micrococcus luteus.

SUBMITTER: Contreras G

PROVIDER: S-EPMC6181372 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Recombinant AfusinC, an anionic fungal CSαβ defensin from Aspergillus fumigatus, exhibits antimicrobial activity against gram-positive bacteria.

Contreras Gabriela G Braun Markus Santhosh MS Schäfer Holger H Wink Michael M

PloS one 20181011 10

Antimicrobial peptides (AMPs) are short and generally positively charged peptides found in a wide variety of organisms. CSαβ defensins are a group of AMPs. These defensins are composed of an α-helix and a β-sheet linked by three or four disulphide bridges. In this study, we describe the antimicrobial activity of an anionic CSαβ fungal defensin from Aspergillus fumigatus, AfusinC. AfusinC was recombinantly produced as a fusion protein in Escherichia coli. The tag was removed by proteolytic cleava ...[more]

PMID: 30308015

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Project description:Microbial secondary metabolites, including isocyanide moieties, have been extensively mined for their repertoire of bioactive properties. Although the first naturally occurring isocyanide (xanthocillin) was isolated from the fungus Penicillium notatum over half a century ago, the biosynthetic origins of fungal isocyanides remain unknown. Here we report the identification of a family of isocyanide synthases (ICSs) from the opportunistic human pathogen Aspergillus fumigatus Comparative metabolomics of overexpression or knockout mutants of ICS candidate genes led to the discovery of a fungal biosynthetic gene cluster (BGC) that produces xanthocillin (xan). Detailed analysis of xanthocillin biosynthesis in A. fumigatus revealed several previously undescribed compounds produced by the xan BGC, including two novel members of the melanocin family of compounds. We found both the xan BGC and a second ICS-containing cluster, named the copper-responsive metabolite (crm) BGC, to be transcriptionally responsive to external copper levels and further demonstrated that production of metabolites from the xan BGC is increased during copper starvation. The crm BGC includes a novel type of fungus-specific ICS-nonribosomal peptide synthase (NRPS) hybrid enzyme, CrmA. This family of ICS-NRPS hybrid enzymes is highly enriched in fungal pathogens of humans, insects, and plants. Phylogenetic assessment of all ICSs spanning the tree of life shows not only high prevalence throughout the fungal kingdom but also distribution in species not previously known to harbor BGCs, indicating an untapped resource of fungal secondary metabolism.IMPORTANCE Fungal ICSs are an untapped resource in fungal natural product research. Their isocyanide products have been implicated in plant and insect pathogenesis due to their ability to coordinate transition metals and disable host metalloenzymes. The discovery of a novel isocyanide-producing family of hybrid ICS-NRPS enzymes enriched in medically and agriculturally important fungal pathogens may reveal mechanisms underlying pathogenicity and afford opportunities to discover additional families of isocyanides. Furthermore, the identification of noncanonical ICS BGCs will enable refinement of BGC prediction algorithms to expand on the secondary metabolic potential of fungal and bacterial species. The identification of genes related to ICS BGCs in fungal species not previously known for secondary metabolite-producing capabilities (e.g., Saccharomyces spp.) contributes to our understanding of the evolution of BGC in fungi.

Project description:Antimicrobial peptides (AMPs) are currently recognized as potentially promising antibiotic substitutes. Fish are an important seawater/freshwater medicinal biological resource, and the antimicrobial peptides and proteins that are key components of their innate immune systems are potential candidates for the development of novel antibacterial agents. The rainbow trout Oncorhynchus mykiss chemokine CK11 (omCK11), classified in the C-C motif chemokine ligand 27/28 (CCL27/28) family, is the only CC-type chemokine reported to play a direct antibacterial role in the immune response; however, its antibacterial domain remains unknown. In this study, we analyzed the structure-activity relationship of omCK11 and identified the antibacterial C-terminal domain. Additionally, we performed structure-function analyses of CCL27/28 proteins from different, representative freshwater and seawater fishes, revealing their shared C-terminal antibacterial domains. Surprisingly, a synthesized cationic peptide (named lcCCL28-25), derived from the large yellow croaker Larimichthys crocea CCL28, exhibited broad-spectrum and the most acceptable bactericidal activity, as well as antibiofilm activity and negligible hemolytic and cytotoxic activity in vitro. Additionally, lcCCL28-25 conferred a protective effect in the thighs of neutropenic mice infected with Staphylococcus aureus. SYTOX green fluorescence and electron microscopy experiments revealed that lcCCL28-25 was capable of rapidly destroying the integrity and permeability of the bacterial cell membrane. Overall, this study aided in the advancement of antibacterial CC-type chemokine research and also suggested a new strategy for exploring novel AMPs. Additionally, the efficacy of lcCCL28-25 in in vivo antibacterial activity in a mammalian model revealed that this compound could be a promising agent for the development of peptide-based antibacterial therapeutics. IMPORTANCE The primary function of chemokines has been described as recruiting and activating leukocytes to participate in the immune response. Some chemokines are also broad-spectrum antibacterial proteins in mammals. The Oncorhynchus mykiss chemokine CK11 (omCK11) is the first reported and currently the only CC-type antibacterial chemokine. The present study identified the antibacterial domain of omCK11. Structure-function analysis of various fish CCL27/28 proteins identified a novel antibacterial peptide (lcCCL28-25) from Larimichthys crocea CCL28 that exhibited broad-spectrum and the most acceptable bactericidal activity in vitro, as well as a protective effect in a Staphylococcus aureus infection mouse model. The antibacterial mechanisms included membrane disruption and permeation. This study advanced the field of antibacterial chemokine research in fish and also suggested a new strategy for exploring novel AMPs. The novel peptide lcCCL28-25 may prove to be an effective antibacterial agent.

Dataset Information

Recombinant AfusinC, an anionic fungal CS?? defensin from Aspergillus fumigatus, exhibits antimicrobial activity against gram-positive bacteria.

Publications

Recombinant AfusinC, an anionic fungal CSαβ defensin from Aspergillus fumigatus, exhibits antimicrobial activity against gram-positive bacteria.

Similar Datasets

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