Chronic intracellular infection of alfalfa nodules by Sinorhizobium meliloti requires correct lipopolysaccharide core

AUTOR(ES)

Campbell, Gordon R. O.

FONTE

The National Academy of Sciences

RESUMO

Our analyses of lipopolysaccharide mutants of Sinorhizobium meliloti offer insights into how this bacterium establishes the chronic intracellular infection of plant cells that is necessary for its nitrogen-fixing symbiosis with alfalfa. Derivatives of S. meliloti strain Rm1021 carrying an lpsB mutation are capable of colonizing curled root hairs and forming infection threads in alfalfa in a manner similar to a wild-type strain. However, developmental abnormalities occur in the bacterium and the plant at the stage when the bacteria invade the plant nodule cells. Loss-of-function lpsB mutations, which eliminate a protein of the glycosyltransferase I family, cause striking changes in the carbohydrate core of the lipopolysaccharide, including the absence of uronic acids and a 40-fold relative increase in xylose. We also found that lpsB mutants were sensitive to the cationic peptides melittin, polymyxin B, and poly-l-lysine, in a manner that paralleled that of Brucella abortus lipopolysaccharide mutants. Sensitivity to components of the plant's innate immune system may be part of the reason that this mutant is unable to properly sustain a chronic infection within the cells of its host-plant alfalfa.

Documentos Relacionados

• Sinorhizobium meliloti Sulfotransferase That Modifies Lipopolysaccharide
• Developmental fate of Rhizobium meliloti bacteroids in alfalfa nodules.
• Diversity of Sinorhizobium meliloti from the Central Asian Alfalfa Gene Center
• Alfalfa Root Nodule Invasion Efficiency Is Dependent on Sinorhizobium meliloti Polysaccharides
• Ultrastructural analysis of ineffective alfalfa nodules formed by nif::Tn5 mutants of Rhizobium meliloti.