Jouni Jokela

University of Helsinki | HY · Department of Microbiology

Microcystins (MCs) are a family of chemically diverse toxins produced by numerous distantly related cyanobacteria. They are potent inhibitors of eukaryotic protein phosphatases 1 and 2A and are responsible for the toxicosis and death of wild and domestic animals around the world. Microcystins are synthesized on large enzyme complexes comprised of p...

MAA biosynthetic enzymes encoded in two distant sections of the genome work together to form two diglycosylated MAA structural variants.

Mycosporine-like amino acids (MAAs) are small, colorless, and water-soluble secondary metabolites. They have high molar extinction coefficients and a unique UV radiation absorption mechanism that make them effective sunscreens. Here we report the discovery of two structurally distinct MAAs from the lichen symbiont strain Nostoc sp. UHCC 0926. We id...

Toxic benthic mats of cyanobacteria are associated with water quality problems and animal poisonings around the world. A strain of the filamentous cyanobacterial genus Kamptonema was isolated from a water bloom in the Baltic Sea four decades ago and later shown to produce cylindrospermopsins. However, the exact habitat of this strain remains unclea...

Radiosumins are a structurally diverse family of low molecular weight natural products that are produced by cyanobacteria and exhibit potent serine protease inhibition. Members of this family are dipeptides characterized by the presence of two similar non-proteinogenic amino acids. Here we used a comparative bioinformatic analysis to identify radio...

CyanoMetDB is a comprehensive database of secondary metabolites from cyanobacteria manually curated from primary references described in Jones et al (2021), DOI: 10.1016/j.watres.2021.117017 (preprint DOI: 10.1101/2020.04.16.038703). This upload contains the 2023 release. Please cite Jones et al (2021) DOI: 10.1016/j.watres.2021.117017 and this rec...

Cyanobactins are linear and cyclic post-translationally modified peptides. Here we show that the prenyl-D-Arg-containing autumnalamide A is a member of the cyanobactin family. Biochemical assays demonstate that the AutF prenyltransferase...

Cyanobacteria are a group of oxygenic photosynthetic prokaryotes found in almost all habitats on earth including those characterized as extreme environments. It has been observed that the number of studies dealing with the biodiversity of extremophilic cyanobacteria is limited while studies exploring their bioactive potential are even scarcer. The...

Low-molecular weight natural products display vast structural diversity and have played a key role in the development of novel therapeutics. Here we report the discovery of novel members of the aeruginosin family of natural products, which we named varlaxins. The chemical structures of varlaxins 1046A and 1022A were determined using a combination o...

Serine proteases regulate many physiological processes and play a key role in a variety of cancers. Aeruginosins are a family of natural products produced by cyanobacteria that exhibit pronounced structural diversity and potent serine protease inhibition. Here, we sequenced the complete genome of Nodularia sphaerocarpa UHCC 0038 and identified the...

Laxaphycins are a family of cyclic lipopeptides with synergistic antifungal and antiproliferative activities. They are produced by multiple cyanobacterial genera and comprise two sets of structurally unrelated 11- and 12-residue macrocyclic lipopeptides. Here, we report the discovery of new antifungal laxaphycins from Nostoc sp. UHCC 0702, which we...

Cyanobacteria produce a variety of chemically diverse cyclic lipopeptides with potent antifungal activities. These cyclic lipopeptides have an ampiphatic structure comprised of a polar peptide cycle and hydrophobic fatty acid side chain. Many have antibiotic activity against a range of human and plant fungal pathogens. This review article aims to s...

Harmful cyanobacterial blooms, which frequently contain toxic secondary metabolites, are reported in aquatic environments around the world. More than two thousand cyanobacterial secondary metabolites have been reported from diverse sources over the past fifty years. A comprehensive, publically-accessible database detailing these secondary metabolit...

Cyanobacteria produce a wide range of lipopeptides that exhibit potent membrane-disrupting activities. Laxaphycins consist of two families of structurally distinct macrocyclic lipopeptides that act in a synergistic manner to produce antifungal and antiproliferative activities. Laxaphycins are produced by range of cyanobacteria but their biosyntheti...

Bacteria produce a wide range of lipopeptides that exhibit membrane-disrupting activities. Laxaphycins are structurally distinct macrocyclic lipopeptides that act together to produce synergistic antifungal and antiproliferative activities. Laxaphycins are produced by range of cyanobacteria but their biosynthetic origins remain unclear. Here we iden...

Cyanobacteria form harmful mass blooms in freshwater and marine environments around the world. A range of secondary metabolites has been identified from cultures of cyanobacteria and biomass collected from cyanobacterial bloom events. A comprehensive database is necessary to correctly identify cyanobacterial metabolites and advance research on thei...

Cyanobacteria are photosynthetic organisms that produce a large diversity of natural products with interesting bioactivities for biotechnological and pharmaceutical applications. Cyanobacterial extracts exhibit toxicity towards other microorganisms and cancer cells and, therefore, represent a source of potentially novel natural products for drug di...

Prenylation is a common step in the biosynthesis of many natural products and plays an important role in increasing their structural diversity and enhancing biological activity. Muscoride A is a linear peptide alkaloid that contain two contiguous oxazoles and unusual prenyl groups that protect the amino and carboxy termini. Here we identified the 1...

Hassallidins are cyclic glycolipopeptides produced by cyanobacteria and other prokaryotes. The hassallidin structure consists of a peptide ring of eight amino acids where a fatty acid chain, additional amino acids, and sugar moieties are attached. Hassallidins show antifungal activity against several opportunistic human pathogenic fungi, but does n...

Microcystins are a family of chemically diverse hepatotoxins produced by distantly related cyanobacteria and are potent inhibitors of eukaryotic protein phosphatases 1 and 2A. Here we provide evidence for the biosynthesis of rare variants of microcystin that contain a selection of homo-amino acids by the benthic strain Phormidium sp. LP904c. This s...

Herein, we deciphered the most important biosynthetic traits of a prominent group of bioactive lipopeptides. We reveal evidence for initiation of biosynthesis by two alternative starter units hardwired directly in the same gene cluster, eventually resulting in the production of a remarkable range of lipopeptide variants. We identified several unusu...

Aromatic prenylation is an important step in the biosynthesis of many natural products and leads to an astonishing diversity of chemical structures. Cyanobactin pathways frequently encode aromatic prenyltransferases that catalyze the prenylation of these macrocyclic and linear peptides. Here we characterized the anacyclamide (acy) biosynthetic gene...

Cyanobactins are a family of linear and cyclic peptides produced through the post-translational modification of short precursor peptides. A mass spectrometry-based screening of potential cyanobactin producers led to the discovery of a new prenylated member of this family of compounds, sphaerocyclamide (1), from Sphaerospermopsis sp. LEGE 00249. The...

Recent works provide evidence of the prebiotic potential of arabinoxylan-derived oligosaccharides (A)XOS. In this study, we developed a structural analysis for cereal-derived (A)XOS by negative ionization HILIC-MS/MS. Initially, we assessed twelve (A)XOS samples of known structures with different linkage positions and branching points by direct-inf...

Prenylation is a widespread modification that im-proves the biological activities of secondary metab-olites. This reaction also represents a key modifica-tion step in biosyntheses of cyanobactins, a family of ribosomally synthesized and posttranslationally modified peptides (RiPPs) produced by cyanobac-teria. In cyanobactins, amino acids are common...

The pederin family includes a number of bioactive compounds isolated from symbiotic organisms of diverse evolutionary origin. Pederin is linked to beetle-induced dermatitis in humans and pederin family members possess potent antitumor activity caused by selective inhibition of the eukaryotic ribosome. Their biosynthesis is accomplished by a polyket...

Absorption and MS spectra of carotenoids identified in Anabaena sp. PCC 7120 and Calothrix sp. 336/3 samples.

Swinholides are 42-carbon ring polyketides with a 2-fold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be th...

Microcystins (MCs) are serine/threonine phosphatase inhibitors synthesized by several members of the phylum Cyanobacteria. Mining the draft genome sequence of the nostocalean MC-producing Fischerella sp. strain CENA161 led to the identification of three contigs containing mcy genes. Subsequent PCR and Sanger sequencing allowed the assembling of its...

Nostoc is a cyanobacterial genus, common in soils and a prolific producer of natural products. This research project aimed to explore and characterize Brazilian cyanobacteria for new bioactive compounds. Here we report the production of hepatotoxins and new protease inhibitors from benthic Nostoc sp. CENA543 isolated from a small, shallow, saline-a...

Anabaenopeptins are a diverse group of cyclic peptides, which contain an unusual ureido linkage. Namalides are shorter structural homologs of anabaenopeptins, which also contain an ureido linkage. The biosynthetic origins of namalides are unknown despite a strong resemblance to anabaenopeptins. Here we show the cyanobacterium Nostoc sp. CENA543 str...

Macrocyclic peptides have promising therapeutic potential but the scaling up of their chemical synthesis is challenging. The cyanobactin macrocyclase, PatGmac, is an efficient tool for production but is limited to...

Cyanobacteria produce a wide range of natural products with antifungal bioactivity. The cyclic glycosylated lipopeptides of the hassallidin family have potent antifungal activity and display a great degree of chemical diversity. Here we report the discovery of a hassallidin biosynthetic gene cluster from the filamentous cyanobacterium Planktothrix...

Cyanobacteria produce a broad range of natural products many of which are potent protease inhibitors. Biosynthetic gene clusters encoding the production of novel protease inhibitors belonging to the spumigin and anabaenopeptin family of non-ribosomal peptides were identified in the genome of the bloom-forming cyanobacterium Sphaerospermopsis torque...

Cyanobactins are a family of linear and cyclic peptides produced through the post-translational modification of short precursor peptides. Anacyclamides are macrocyclic cyanobactins with a highly diverse sequence that are common in the genus Anabaena . A mass spectrometry-based screening of potential cyanobactin producers led to the discovery of a n...

The carotenoid composition of the filamentous heterocystous N2-fixing cyanobacterium Calothrix sp. 336/3 was investigated under three conditions: in full medium (non-diazotrophic growth); in the absence of combined nitrogen (diazotrophic growth); and after long-term H2 photoproduction (diazotrophic medium and absence of nitrogen in atmosphere). Ana...

Talaromyces islandicus ("Penicillium islandicum") is a widespread foodborne mold that produces numerous secondary metabolites, among them potent mycotoxins belonging to different chemical classes. A notable metabolite is the hepatotoxic and carcinogenic pentapeptide cyclochlorotine that contains the unusual amino acids β-phenylalanine, 2-aminobutyr...

Significance Cyclodextrins are cyclic oligosaccharides used in the pharmaceutical industry to improve drug delivery. Here, we show that cyclodextrins improve the antifungal activity of the anabaenolysins A and B lipopeptides and that are both produced by the same cyanobacteria. This study identifies the putative biosynthetic gene cluster involved i...

Cyanobacteria are an inspiring source of bioactive secondary metabolites. These bioactive agents are a diverse group of compounds which are varying in their bioactive targets, the mechanisms of action, and chemical structures. Cyanobacteria from various environments, especially marine benthic cyanobacteria, are found to be rich sources for the sear...

Cyanobacteria are photosynthetic prokaryotes found in a range of environments. They are infamous for the production of toxins, as well as bioactive compounds, which exhibit anticancer, antimicrobial and protease inhibition activities. Cyanobacteria produce a broad range of antifungals belonging to structural classes, such as peptides, polyketides a...

Abstract Geosmin and 2-methylisoborneol (MIB) are muddy/earthy off-flavor metabolites produced by a range of bacteria. Cyanobacteria are the major producers of the volatile metabolites geosmin and MIB which produce taste and odor problems in drinking water and fish worldwide. Here we detected geosmin and MIB by studying 100 cyanobacteria strains u...

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Nodularia spumigena is a filamentous cyanobacterium that forms toxic blooms in brackish waters around the world through the production of the pentapeptide toxin nodularin. This cyanobacterium also produces large amounts of protease inhibitors belonging to the aeruginosin and spumigin families. Here we report the discovery of previously unkown prote...

BACKGROUND: Cyanobacteria are an ancient lineage of photosynthetic bacteria from which hundreds of natural products have been described, including many notorious toxins but also potent natural products of interest to the pharmaceutical and biotechnological industries. Many of these compounds are the products of non-ribosomal peptide synthetase (NR...

The 4-methylproline (4-mPro) is a rare non-proteinogenic amino acid produced by cyanobacteria through the action of a zinc-dependent long-chain dehydrogenase and a Δ1-pyrroline-5-carboxylic acid (P5C) reductase homologue. Here we used the presence of the 4-mPro biosynthetic genes to discover new bioactive compounds from cyanobacteria. Eight biosynt...

Two new trypsin inhibitors, nostosin A (1) and B (2), were isolated from a hydrophilic extract of Nostoc sp. strain FSN, which was collected from a paddy field in the Golestan Province of Iran. Nostosins A (1) and B (2) are composed of three subunits, 2-hydroxy-4-(4-hydroxyphenyl)butanoic acid (Hhpba), l-Ile, and l-argininal (1) or argininol (2). N...

Significance New antifungal compounds are needed due to an increasing incidence of invasive fungal infections and resistance to many currently used drugs. Here we show that cyanobacteria are a rich source of antifungal compounds such as glycosylated lipopeptides, called hassallidins, which are commonly produced by filamentous nitrogen-fixing cyanob...

In this study, we investigated forty cyanobacterial isolates from biofilms, gastropods, brackish water and symbiotic lichen habitats. Their aqueous and organic extracts were used to screen for apoptosis-inducing activity against acute myeloid leukemia cells. A total of 28 extracts showed cytotoxicity against rat acute myeloid leukemia (IPC-81) cell...

Aeruginosin-865 (Aer-865), isolated from terrestrial cyanobacterium Nostoc sp. Lukešová 30/93, is the first aeruginosin-type peptide containing both a fatty acid and a carbohydrate moiety, and is the first aeruginosin to be found in the genus Nostoc. Mass spectrometry, chemical and spectroscopic analysis as well as one- and two-dimensional NMR and...

Screening of fifty-five different cyanobacterial strains revealed that an extract from Nostoc XPORK14A drastically modifies the amplitude and kinetics of chlorophyll a fluorescence induction of Synechocystis PCC 6803 cells. After two days exposure to the Nostoc XPORK14A extract, Synechocystis PCC 6803 cells displayed reduced net photosynthetic acti...

Mass spectrometric analysis was used to compare the roles of two acetyl esterases (AE, carbohydrate esterase family CE16) and three acetyl xylan esterases (AXE, families CE1 and CE5) in deacetylation of natural substrates, neutral (linear) and 4-O-methyl glucuronic acid (MeGlcA) substituted xylooligosaccharides (XOS). AEs were similarly restricted...

Nodularia spumigena is a filamentous diazotrophic cyanobacterium that forms blooms in brackish water bodies. This cyanobacterium produces linear and cyclic peptide protease inhibitors which are thought to be part of a chemical defense against grazers. Here we show that N. spumigena produces structurally novel members of the aeruginosin family of se...

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