Tolyporphins L–R: Unusual Tetrapyrroles from a <i>Brasilonema</i> sp. of Cyanobacterium

Gurr, Joshua R.; Dai, Jingqiu; Philbin, Casey S.; Sartain, Hope T.; O’Donnell, Timothy J.; Yoshida, Wesley Y.; Rheingold, Arnold L.; Williams, Philip G.

doi:10.1021/acs.joc.9b01928

Cited by 14 publications

(23 citation statements)

References 26 publications

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“…The molecular structure (including stereochemistry) of tolyporphin A has been confirmed by total synthesis (12–14) and more recently by single‐crystal X‐ray structure analysis (11). The structures of tolyporphins E and R also have been confirmed by X‐ray crystallography (11). The structures are shown in Chart 1.…”

Section: Introductionmentioning

confidence: 92%

“…The discovery of tolyporphin A in a cyanobacterial culture in Micronesia in the late 1980s by a team from the University of Hawaii (3) has also raised many such questions, particularly since the absorption spectrum resembles that of chlorophyll a , the compound is photoactive (4, 5), the structure lies outside the known biosynthetic paradigm for tetrapyrroles (6, 7), and the chromophore of tolyporphin A is a dioxobacteriochlorin yet the compound is found in a (chlorophyll‐containing) cyanobacterium. A family of tolyporphins has subsequently been discovered, now including tolyporphins A–R (8–11). The molecular structure (including stereochemistry) of tolyporphin A has been confirmed by total synthesis (12–14) and more recently by single‐crystal X‐ray structure analysis (11).…”

Section: Introductionmentioning

confidence: 99%

“…A family of tolyporphins has subsequently been discovered, now including tolyporphins A–R (8–11). The molecular structure (including stereochemistry) of tolyporphin A has been confirmed by total synthesis (12–14) and more recently by single‐crystal X‐ray structure analysis (11). The structures of tolyporphins E and R also have been confirmed by X‐ray crystallography (11).…”

Section: Introductionmentioning

confidence: 99%

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Fluorescence Assay for Tolyporphins Amidst Abundant Chlorophyll in Crude Cyanobacterial Extracts

Nguyen

Zhang

Taniguchi

et al. 2021

Photochem & Photobiology

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Tolyporphins are distinctive tetrapyrrole natural products found singularly in a filamentous cyanobacterial‐microbial holobiont (termed HT‐58‐2) from Micronesia. The absorption and fluorescence features of tolyporphins resemble those of chlorophyll a, complicating direct analysis of culture samples. Treatment of the crude (unfractionated) organic extract (CH2Cl2/2‐propanol, 1:1) of HT‐58‐2 cultures with NaBH4 in methanol causes reduction of the peripheral ketone auxochromes, whereupon tolyporphins (predominantly 7,17‐dioxobacteriochlorins) exhibit a bathochromic shift (λabs ˜ 676 → ˜ 700 nm) and chlorophyll a (a 131‐oxochlorin) exhibits a hypsochromic shift (λabs 665 → 634 nm). Fluorescence excitation spectroscopy (at 368 and 491 nm with λem 710 nm) enabled detection of reduced tolyporphins amidst abundant reduced chlorophyll a (1:19 ratio), a detection sensitivity >5 times that without reduction. The resulting assay combines simple sample preparation from non‐axenic cultures at microscale quantities (2 mL, 2 μm), absence of any fractionation procedures, and fluorescence detection. Tolyporphins were readily detected in cultures of HT‐58‐2 at reasonable growth periods in the absence of environmental stressors, which was not possible previously.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fluorescence Assay for Tolyporphins Amidst Abundant Chlorophyll in Crude Cyanobacterial Extracts

Nguyen

Zhang

Taniguchi

et al. 2021

Photochem & Photobiology

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“…The cyanobacterial culture, labeled HT-58-2, was collected on the island of Pohnpei in Micronesia. Since then, a family of tolyporphin analogues (B–R) has been identified in the HT-58-2 culture [ 10 , 11 , 12 ]. Tolyporphins are the only new class of tetrapyrrole macrocycles reported since the discovery of the F 430 coenzyme of methanogenesis.…”

Section: Introductionmentioning

confidence: 99%

Identification of Putative Biosynthetic Gene Clusters for Tolyporphins in Multiple Filamentous Cyanobacteria

Jin

Zhang

et al. 2021

Life

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Tolyporphins A–R are unusual tetrapyrrole macrocycles produced by the non-axenic filamentous cyanobacterium HT-58-2. A putative biosynthetic gene cluster for biosynthesis of tolyporphins (here termed BGC-1) was previously identified in the genome of HT-58-2. Here, homology searching of BGC-1 in HT-58-2 led to identification of similar BGCs in seven other filamentous cyanobacteria, including strains Nostoc sp. 106C, Nostoc sp. RF31YmG, Nostoc sp. FACHB-892, Brasilonema octagenarum UFV-OR1, Brasilonema octagenarum UFV-E1, Brasilonema sennae CENA114 and Oculatella sp. LEGE 06141, suggesting their potential for tolyporphins production. A similar gene cluster (BGC-2) also was identified unexpectedly in HT-58-2. Tolyporphins BGCs were not identified in unicellular cyanobacteria. Phylogenetic analysis based on 16S rRNA and a common component of the BGCs, TolD, points to a close evolutionary history between each strain and their respective tolyporphins BGC. Though identified with putative tolyporphins BGCs, examination of pigments extracted from three cyanobacteria has not revealed the presence of tolyporphins. Overall, the identification of BGCs and potential producers of tolyporphins presents a collection of candidate cyanobacteria for genetic and biochemical analysis pertaining to these unusual tetrapyrrole macrocycles.

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“…Cyanobacteria employ chlorophyll, not bacteriochlorophyll, for photosynthesis, and the presence of compounds with a bacteriochlorin chromophore in a chlorin-based photosynthetic system is unprecedented. Over the years, fractionation of lipophilic extracts from the HT-58-2 culture has led to the identification of a family of tolyporphins, now numbering 18 (A-R) [6][7][8] (Figure 1). Most of the tolyporphins are dioxobacteriochlorins, but three are oxochlorins, and one is a porphyrin.…”

Section: Introductionmentioning

confidence: 99%

Natural Product Gene Clusters in the Filamentous Nostocales Cyanobacterium HT-58-2

Jin

Miller

Lindsey

2021

Life

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Cyanobacteria are known as rich repositories of natural products. One cyanobacterial-microbial consortium (isolate HT-58-2) is known to produce two fundamentally new classes of natural products: the tetrapyrrole pigments tolyporphins A–R, and the diterpenoid compounds tolypodiol, 6-deoxytolypodiol, and 11-hydroxytolypodiol. The genome (7.85 Mbp) of the Nostocales cyanobacterium HT-58-2 was annotated previously for tetrapyrrole biosynthesis genes, which led to the identification of a putative biosynthetic gene cluster (BGC) for tolyporphins. Here, bioinformatics tools have been employed to annotate the genome more broadly in an effort to identify pathways for the biosynthesis of tolypodiols as well as other natural products. A putative BGC (15 genes) for tolypodiols has been identified. Four BGCs have been identified for the biosynthesis of other natural products. Two BGCs related to nitrogen fixation may be relevant, given the association of nitrogen stress with production of tolyporphins. The results point to the rich biosynthetic capacity of the HT-58-2 cyanobacterium beyond the production of tolyporphins and tolypodiols.

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Tolyporphins L–R: Unusual Tetrapyrroles from a Brasilonema sp. of Cyanobacterium

Cited by 14 publications

References 26 publications

Fluorescence Assay for Tolyporphins Amidst Abundant Chlorophyll in Crude Cyanobacterial Extracts

Fluorescence Assay for Tolyporphins Amidst Abundant Chlorophyll in Crude Cyanobacterial Extracts

Identification of Putative Biosynthetic Gene Clusters for Tolyporphins in Multiple Filamentous Cyanobacteria

Natural Product Gene Clusters in the Filamentous Nostocales Cyanobacterium HT-58-2

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