High levels of structural diversity observed in microcystins from Microcystis CAWBG11 and characterization of six new microcystin congeners.
Microcystins (MCs) are cyclic peptides produced by cyanobacteria, which can be harmful to humans and animals when ingested. Differences in the coding of the non‑ribosomal peptide synthetase/polyketide synthase enzyme complex responsible for microcystin production have resulted in more than 100 microcystin variants being reported to date. The microcystin diversity of Microcystis CAWBG11 was investigated using matrix-assisted laser desorption/ionization-time of flight mass spectrometry and liquid chromatography-mass spectrometry. This revealed that CAWBG11 simultaneously produced 21 known microcystins and six new congeners: [Asp3] MC-RA, [Asp3] MC-RAba, [Asp3] MC-FA, [Asp3] MC-WA, MC-FAba and MC-FL. The new congeners were putatively characterized by tandem mass spectrometry and chemical derivatization. A survey of the microcystin congeners produced by 49 cyanobacterial strains documented in scientific literature showed that cyanobacteria generally produce four microcystin congeners, but strains which produce up to 47 microcystin congeners have been reported. Microcystis CAWBG11 (which produces at least 27 congeners) was positioned in the top ten percentile of the strains surveyed, and showed fluidity of the amino acids incorporated into both position two and position four.
Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. jonathan.puddick@cawthron.org.nz.
Jonathan
J
Puddick
Chemistry Department, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. m.prinsep@waikato.ac.nz.
Michèle R
MR
Prinsep
Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. caryc@waikato.ac.nz.
Susanna A
SA
Wood
Chemistry Department, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. sfk1@students.waikato.ac.nz.
Sangata A F
SA
Kaufononga
Biology Department, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. caryc@waikato.ac.nz.
Stephen Craig
SC
Cary
Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. d.hamilton@waikato.ac.nz.
David P
DP
Hamilton
D000595:Amino Acid Sequence; D002853:Chromatography, Liquid / Q000379:methods; D000458:Cyanobacteria / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D052998:Microcystins / Q000737:chemistry* / Q000302:isolation & purification; D046931:Microcystis / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods
D052998:Microcystins