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Sulfur Deficiency Changes Mycosporine‐like Amino Acid (MAA) Composition of Anabaena variabilis PCC 7937: A Possible Role of Sulfur in MAA Bioconversion
Author(s) -
Singh Shailendra P.,
Klisch Manfred,
Sinha Rajeshwar P.,
Häder DonatPeter
Publication year - 2010
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2010.00736.x
Subject(s) - methionine , glycine , sulfur , serine , chemistry , biochemistry , anabaena variabilis , decarboxylation , amino acid , cyanobacteria , enzyme , biology , bacteria , organic chemistry , genetics , catalysis
In the present investigation we show for the first time that bioconversion of a primary mycosporine‐like amino acid (MAA) into a secondary MAA is regulated by sulfur deficiency in the cyanobacterium Anabaena variabilis PCC 7937. This cyanobacterium synthesizes the primary MAA shinorine (RT = 2.2 min, λ max = 334 nm) under normal conditions (PAR + UV‐A + UV‐B); however, under sulfur deficiency, a secondary MAA palythine‐serine (RT = 3.9 min, λ max = 320 nm) appears. Addition of methionine to sulfur‐deficient cultures resulted in the disappearance of palythine‐serine, suggesting the role of primary MAAs under sulfur deficiency in recycling of methionine by donating the methyl group from the glycine subunit of shinorine to tetrahydrofolate to regenerate the methionine from homocysteine. This is also the first report for the synthesis of palythine‐serine by cyanobacteria which has so far been reported only from corals. Addition of methionine also affected the conversion of mycosporine‐glycine into shinorine, consequently, resulted in the appearance of mycosporine‐glycine (RT = 3.6 min, λ max = 310 nm). Our results also suggest that palythine‐serine is synthesized from shinorine. Based on these results we propose that glycine decarboxylase is the potential enzyme that catalyzes the bioconversion of shinorine to palythine‐serine by decarboxylation and demethylation of the glycine unit of shinorine.