Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>

In non-ribosomal peptide synthesis of cyanobacteria, promiscuous adenylation domains allow the incorporation of clickable non-natural amino acids into peptide products—namely into microcystins (MCs) or into anabaenopeptins (APs): 4-azidophenylalanine (Phe-Az), <i>N</i>-propargyloxy-carbo...

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Main Authors: Rainer Kurmayer, Rubén Morón Asensio
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Toxins
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Online Access:https://www.mdpi.com/2072-6651/17/6/278
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author Rainer Kurmayer
Rubén Morón Asensio
author_facet Rainer Kurmayer
Rubén Morón Asensio
author_sort Rainer Kurmayer
collection DOAJ
description In non-ribosomal peptide synthesis of cyanobacteria, promiscuous adenylation domains allow the incorporation of clickable non-natural amino acids into peptide products—namely into microcystins (MCs) or into anabaenopeptins (APs): 4-azidophenylalanine (Phe-Az), <i>N</i>-propargyloxy-carbonyl-L-lysine (Prop-Lys), or <i>O</i>-propargyl-L-tyrosine (Prop-Tyr). Subsequently, chemo-selective labeling is used to visualize the clickable cyanopeptides using Alexa Fluor 488 (A488). In this study, the time-lapse build up or decline of azide- or alkyne-modified MCs or APs was visualized during maximum growth, specifically MC biosynthesis in <i>Microcystis aeruginosa</i> and AP biosynthesis in <i>Planktothrix agardhii</i>. Throughout the time-lapse build up or decline, the A488 signal occurred with heterogeneous intracellular distribution. There was a fast increase or decrease in the A488 signal for either Prop-Tyr or Prop-Lys, while a delayed or unobservable A488 signal for Phe-Az was related to increased cell size as well as a reduction in growth and autofluorescence. The proportion of clickable MC/AP in peptide extracts as recorded by a chemical–analytical technique correlated positively with A488 labeling intensity quantified via laser-scanning confocal microscopy for individual cells or via flow cytometry at the population level. It is concluded that chemical modification of MC/AP can be used to track intracellular dynamics in biosynthesis using both analytical chemistry and high-resolution imaging.
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spelling doaj-art-4fb76fa2392e4c20843c0a578f0cdaa32025-08-20T02:21:58ZengMDPI AGToxins2072-66512025-06-0117627810.3390/toxins17060278Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>Rainer Kurmayer0Rubén Morón Asensio1Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, 5310 Mondsee, AustriaResearch Department for Limnology, University of Innsbruck, Mondseestrasse 9, 5310 Mondsee, AustriaIn non-ribosomal peptide synthesis of cyanobacteria, promiscuous adenylation domains allow the incorporation of clickable non-natural amino acids into peptide products—namely into microcystins (MCs) or into anabaenopeptins (APs): 4-azidophenylalanine (Phe-Az), <i>N</i>-propargyloxy-carbonyl-L-lysine (Prop-Lys), or <i>O</i>-propargyl-L-tyrosine (Prop-Tyr). Subsequently, chemo-selective labeling is used to visualize the clickable cyanopeptides using Alexa Fluor 488 (A488). In this study, the time-lapse build up or decline of azide- or alkyne-modified MCs or APs was visualized during maximum growth, specifically MC biosynthesis in <i>Microcystis aeruginosa</i> and AP biosynthesis in <i>Planktothrix agardhii</i>. Throughout the time-lapse build up or decline, the A488 signal occurred with heterogeneous intracellular distribution. There was a fast increase or decrease in the A488 signal for either Prop-Tyr or Prop-Lys, while a delayed or unobservable A488 signal for Phe-Az was related to increased cell size as well as a reduction in growth and autofluorescence. The proportion of clickable MC/AP in peptide extracts as recorded by a chemical–analytical technique correlated positively with A488 labeling intensity quantified via laser-scanning confocal microscopy for individual cells or via flow cytometry at the population level. It is concluded that chemical modification of MC/AP can be used to track intracellular dynamics in biosynthesis using both analytical chemistry and high-resolution imaging.https://www.mdpi.com/2072-6651/17/6/278microcystinanabaenopeptintime-lapse experimentspulse-feedingchemo-selective labelinghigh-resolution microscopy
spellingShingle Rainer Kurmayer
Rubén Morón Asensio
Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>
Toxins
microcystin
anabaenopeptin
time-lapse experiments
pulse-feeding
chemo-selective labeling
high-resolution microscopy
title Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>
title_full Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>
title_fullStr Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>
title_full_unstemmed Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>
title_short Time-Resolved Visualization of Cyanotoxin Synthesis via Labeling by the Click Reaction in the Bloom-Forming Cyanobacteria <i>Microcystis aeruginosa</i> and <i>Planktothrix agardhii</i>
title_sort time resolved visualization of cyanotoxin synthesis via labeling by the click reaction in the bloom forming cyanobacteria i microcystis aeruginosa i and i planktothrix agardhii i
topic microcystin
anabaenopeptin
time-lapse experiments
pulse-feeding
chemo-selective labeling
high-resolution microscopy
url https://www.mdpi.com/2072-6651/17/6/278
work_keys_str_mv AT rainerkurmayer timeresolvedvisualizationofcyanotoxinsynthesisvialabelingbytheclickreactioninthebloomformingcyanobacteriaimicrocystisaeruginosaiandiplanktothrixagardhiii
AT rubenmoronasensio timeresolvedvisualizationofcyanotoxinsynthesisvialabelingbytheclickreactioninthebloomformingcyanobacteriaimicrocystisaeruginosaiandiplanktothrixagardhiii