Glucosylglycerate: a secondary compatible solute common to marine cyanobacteria from nitrogen-poor environments.
The synthesis and accumulation of compatible solutes represent an essential part of the salt acclimation strategy of microorganisms. Glucosylglycerol is considered to be the typical compatible solute among marine cyanobacteria. However, genes that encode enzymes for the synthesis of glucosylglycerol were not detected in the genome sequences of marine picoplanktonic Prochlorococcus strains. Instead, we noticed the presence of genes that putatively encode for glucosylglycerate (GGA) synthesis among Prochlorococcus and most other closely related marine picocyanobacteria. Recombinant proteins from Prochlorococcus marinus SS120 and Synechococcus sp. PCC 7002 exhibited glucosyl-phosphoglycerate synthase (GpgS) activity, and GpgS is a key enzyme of GGA synthesis. GGA accumulation was found to be salt- as well as nitrogen-regulated in the coastal strain Synechococcus sp. PCC 7002. Moreover, GGA was also detected in all picoplanktonic Prochlorococcus and Synechococcus strains harbouring gpgS genes, especially under N-limiting conditions. These results suggest that marine picocyanobacteria acquired the capacity to synthesize the negatively charged compound GGA during their evolution. Our results establish GGA as the fifth most widespread compatible solute among cyanobacteria. Additionally, GGA appears to replace glutamate as an anion to counter monovalent cations in marine picocyanobacteria from N-poor environments.
Klähn
Stephan
S
Universität Rostock, Institut für Biowissenschaften, Abt. Pflanzenphysiologie, Einsteinstrasse 3, D-18059 Rostock, Germany.
Steglich
Claudia
C
Hess
Wolfgang R
WR
Hagemann
Martin
M
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005960:Glucosides / Q000096:biosynthesis*; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D005988:Glyceric Acids; D009584:Nitrogen / Q000378:metabolism*; D010802:Phylogeny; D048929:Prochlorococcus / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D054712:Salinity; D017422:Sequence Analysis, DNA; D046940:Synechococcus / Q000201:enzymology* / Q000235:genetics
C509251:2-glucosylglycerate; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D005960:Glucosides; D005988:Glyceric Acids; D011994:Recombinant Proteins; D005964:Glucosyltransferases; D009584:Nitrogen