Limits...
Roseobacticides: small molecule modulators of an algal-bacterial symbiosis.

Seyedsayamdost MR, Carr G, Kolter R, Clardy J - J. Am. Chem. Soc. (2011)

Bottom Line: A recent study of Phaeobacter gallaeciensis, a member of the large roseobacter clade of α-proteobacteria, and Emiliania huxleyi, a prominent member of the microphytoplankton found in large algal blooms, revealed that an algal senescence signal produced by E. huxleyi elicits the production of novel algaecides, the roseobacticides, from the bacterial symbiont.Structures of the new family members arise from variable substituents at the C3 and C7 positions of the roseobacticide core as the diversifying elements and suggest that the roseobacticides result from modifications and combinations of aromatic amino acids.Together these studies support a model in which algal senescence converts a mutualistic bacterial symbiont into an opportunistic parasite of its hosts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States.

ABSTRACT
Marine bacteria and microalgae engage in dynamic symbioses mediated by small molecules. A recent study of Phaeobacter gallaeciensis, a member of the large roseobacter clade of α-proteobacteria, and Emiliania huxleyi, a prominent member of the microphytoplankton found in large algal blooms, revealed that an algal senescence signal produced by E. huxleyi elicits the production of novel algaecides, the roseobacticides, from the bacterial symbiont. In this report, the generality of these findings are examined by expanding the number of potential elicitors. This expansion led to the identification of nine new members of the roseobacticide family, rare bacterial troponoids, which provide insights into both their biological roles and their biosynthesis. The qualitative and quantitative changes in the levels of roseobacticides induced by the additional elicitors and the elicitors' varied efficiencies support the concept of host-targeted roseobacticide production. Structures of the new family members arise from variable substituents at the C3 and C7 positions of the roseobacticide core as the diversifying elements and suggest that the roseobacticides result from modifications and combinations of aromatic amino acids. Together these studies support a model in which algal senescence converts a mutualistic bacterial symbiont into an opportunistic parasite of its hosts.

Show MeSH
Structures of roseobacticides A–K, of which C–K have been determined in this work. See text for a description.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211371&req=5

fig4: Structures of roseobacticides A–K, of which C–K have been determined in this work. See text for a description.

Mentions: The compounds induced by pCA (7), sinapic acid (8) and ferulic acid (9) were purified from large-scale production cultures of P. gallaeciensis BS107 in the presence of each elicitor using standard solid-phase extraction and HPLC methods. The structures were subsequently solved by 1D and 2D NMR spectroscopy, HR-HPLC-ESI-MS and HR-MS/MS. All structures reported below have an H/C ratio < 1, and NMR analysis alone was usually not sufficient for structural elucidation necessitating HR-MS/MS and chemical degradation analyses. Using these techniques, we were able to elucidate the structures of nine new roseobacticides, which fall into four classes (Figure 4): (1) A phenol family with compounds 1, 13, and 17, which contain a thiomethyl, a methyl persulfide, or a p-hydroxybenzenethiol moiety at C7 and a phenol group at C3; (2) A phenyl family with compounds 2, 14, 16, and 18 containing a thiomethyl, a methyl persulfide, a sulfonate, or a p-hydroxybenzenethiol at C7 and a phenyl group at C3; (3) An indole family with roseobacticides C (12) and F (15), which contain a thiomethyl or a methyl persulfide at C7, and an indole at C3; and (4) A dimer family with roseobacticides J (19) and K (20), which consist of two roseobacticides joined through a disulfide linkage.


Roseobacticides: small molecule modulators of an algal-bacterial symbiosis.

Seyedsayamdost MR, Carr G, Kolter R, Clardy J - J. Am. Chem. Soc. (2011)

Structures of roseobacticides A–K, of which C–K have been determined in this work. See text for a description.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211371&req=5

fig4: Structures of roseobacticides A–K, of which C–K have been determined in this work. See text for a description.
Mentions: The compounds induced by pCA (7), sinapic acid (8) and ferulic acid (9) were purified from large-scale production cultures of P. gallaeciensis BS107 in the presence of each elicitor using standard solid-phase extraction and HPLC methods. The structures were subsequently solved by 1D and 2D NMR spectroscopy, HR-HPLC-ESI-MS and HR-MS/MS. All structures reported below have an H/C ratio < 1, and NMR analysis alone was usually not sufficient for structural elucidation necessitating HR-MS/MS and chemical degradation analyses. Using these techniques, we were able to elucidate the structures of nine new roseobacticides, which fall into four classes (Figure 4): (1) A phenol family with compounds 1, 13, and 17, which contain a thiomethyl, a methyl persulfide, or a p-hydroxybenzenethiol moiety at C7 and a phenol group at C3; (2) A phenyl family with compounds 2, 14, 16, and 18 containing a thiomethyl, a methyl persulfide, a sulfonate, or a p-hydroxybenzenethiol at C7 and a phenyl group at C3; (3) An indole family with roseobacticides C (12) and F (15), which contain a thiomethyl or a methyl persulfide at C7, and an indole at C3; and (4) A dimer family with roseobacticides J (19) and K (20), which consist of two roseobacticides joined through a disulfide linkage.

Bottom Line: A recent study of Phaeobacter gallaeciensis, a member of the large roseobacter clade of α-proteobacteria, and Emiliania huxleyi, a prominent member of the microphytoplankton found in large algal blooms, revealed that an algal senescence signal produced by E. huxleyi elicits the production of novel algaecides, the roseobacticides, from the bacterial symbiont.Structures of the new family members arise from variable substituents at the C3 and C7 positions of the roseobacticide core as the diversifying elements and suggest that the roseobacticides result from modifications and combinations of aromatic amino acids.Together these studies support a model in which algal senescence converts a mutualistic bacterial symbiont into an opportunistic parasite of its hosts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States.

ABSTRACT
Marine bacteria and microalgae engage in dynamic symbioses mediated by small molecules. A recent study of Phaeobacter gallaeciensis, a member of the large roseobacter clade of α-proteobacteria, and Emiliania huxleyi, a prominent member of the microphytoplankton found in large algal blooms, revealed that an algal senescence signal produced by E. huxleyi elicits the production of novel algaecides, the roseobacticides, from the bacterial symbiont. In this report, the generality of these findings are examined by expanding the number of potential elicitors. This expansion led to the identification of nine new members of the roseobacticide family, rare bacterial troponoids, which provide insights into both their biological roles and their biosynthesis. The qualitative and quantitative changes in the levels of roseobacticides induced by the additional elicitors and the elicitors' varied efficiencies support the concept of host-targeted roseobacticide production. Structures of the new family members arise from variable substituents at the C3 and C7 positions of the roseobacticide core as the diversifying elements and suggest that the roseobacticides result from modifications and combinations of aromatic amino acids. Together these studies support a model in which algal senescence converts a mutualistic bacterial symbiont into an opportunistic parasite of its hosts.

Show MeSH