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Nat Commun. 2014 Oct 30;5:5106. doi: 10.1038/ncomms6106.

Covalently linked hopanoid-lipid A improves outer-membrane resistance of a Bradyrhizobium symbiont of legumes.

Author information

1
Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Via Cintia 4, Napoli I-80126, Italy.
2
IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), UMR IRD/SupAgro/INRA/UM2/CIRAD, TA-A82/J, Campus de Baillarguet, 34398 Montpellier cedex 5, France.
3
CNR-Istituto per i Polimeri, Compositi e Biomateriali IPCB, Unità di Catania Via P. Gaifami 18, Catania 95126, Italy.
4
CIRAD, UMR BGPI, Montpellier F-34398, France.
5
Department of Biology, University of Texas, Arlington, Texas, USA.
6
Division of Biology and Biological Engineering, California Institute of Technology and Howards Hughes Medical Institute, Pasadena, California 91125, USA.
7
Division of Bioanalytical Chemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 4a/c, D-23845 Borstel, Germany.
8
Division of Structural Biochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 4a/c, D-23845 Borstel, Germany.
9
1] Department of Biology, University of Texas, Arlington, Texas, USA [2] Division of Biotechnology, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan 570-752, Republic of Korea.

Abstract

Lipopolysaccharides (LPSs) are major components of the outer membrane of Gram-negative bacteria and are essential for their growth and survival. They act as a structural barrier and play an important role in the interaction with eukaryotic hosts. Here we demonstrate that a photosynthetic Bradyrhizobium strain, symbiont of Aeschynomene legumes, synthesizes a unique LPS bearing a hopanoid covalently attached to lipid A. Biophysical analyses of reconstituted liposomes indicate that this hopanoid-lipid A structure reinforces the stability and rigidity of the outer membrane. In addition, the bacterium produces other hopanoid molecules not linked to LPS. A hopanoid-deficient strain, lacking a squalene hopene cyclase, displays increased sensitivity to stressful conditions and reduced ability to survive intracellularly in the host plant. This unusual combination of hopanoid and LPS molecules may represent an adaptation to optimize bacterial survival in both free-living and symbiotic states.

PMID:
25355435
DOI:
10.1038/ncomms6106
[Indexed for MEDLINE]

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