Abstract / Description of output
Cyanobacteria are an ancient clade of photosynthetic prokaryotes, whose worldwide occurrence, especially in water, presents health hazards to humans and animals due to the production of a range of toxins (cyanotoxins). These include the sometimes co-occurring, non-encoded diamino acid neurotoxins 2,4-diaminobutanoic acid (2,4-DAB) and its structural analogue β-N-methylaminoalanine (BMAA). Knowledge of the biosynthetic pathway for2,4-DAB, and its role in cyanobacteria, is lacking. The aspartate 4-phosphate pathway is a known route of 2,4-DAB biosynthesis in other bacteria and in some plant species. Another pathway to 2,4-DAB has been described in Lathyrus species. Here, we use bioinformatics analyses to investigate hypotheses concerning 2,4-DAB biosynthesis in cyanobacteria. We assessed the presence or absence of each enzyme in candidate biosynthesis routes, the aspartate 4-phosphate pathway and a pathway to 2,4-DAB derived from S-adenosyl-Lmethionine(SAM), in 130 cyanobacterial genomes using sequence alignment, profile hidden Markov models, substrate specificity/active site identification and the reconstruction of gene phylogenies. In the aspartate 4-phosphate pathway, for the 18 species encodingdiaminobutanoate-2-oxo-glutarate transaminase, the co-localisation of genes encoding the transaminase with the downstream decarboxylase or ectoine synthase – often within hybrid non-ribosomal peptide synthetase (NRPS)-polyketide synthases (PKS) clusters, NRPS independent siderophore (NIS) clusters and incomplete ectoine clusters – is compatible with the hypothesis that some cyanobacteria use the aspartate 4-phosphate pathway for 2,4-DABproduction. Through this route, in cyanobacteria, 2,4-DAB may be functionally associated with environmental iron-scavenging, via the production of siderophores of the schizokinen/synechobactin type and of some polyamines. In the pathway to 2,4-DAB derived from SAM, eight cyanobacterial species encode homologs of SAM-dependent 3-amino-3-carboxypropyl transferases. Other enzymes in this pathway have not yet been purified or sequenced. Ultimately, the biosynthesis of 2,4-DAB appears to be either restricted to some cyanobacterial species, or there may be multiple and additional routes, and roles, for the synthesis of this neurotoxin.
Original language | English |
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Article number | 112953 |
Number of pages | 14 |
Journal | Phytochemistry |
Volume | 192 |
Early online date | 29 Sept 2021 |
DOIs | |
Publication status | Published - 16 Nov 2021 |
Keywords / Materials (for Non-textual outputs)
- cyanobacteria
- cyanotoxin
- 4-DAB
- 4-diaminobutanoic acid
- 4-diaminobutyric acid,
- bioinformatics
- diaminobutanoate-2-oxo-glutarate transaminase
- diaminobutanoate decarboxylase
- siderophore
- ectoine
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Additional files for 'Genomic insights into the biosynthesis and physiology of the cyanobacterial neurotoxin 2,4-diaminobutanoic acid (2,4-DAB)'
De Quintanilha Mantas, M. (Creator), Nunn, P. B. (Creator), Ke, Z. (Creator), Codd, G. A. (Creator) & Barker, D. (Creator), Edinburgh DataShare, 9 Jun 2021
DOI: 10.7488/ds/3057
Dataset