Different Phenotypic Classes of Sinorhizobium meliloti Mutants Defective in Synthesis of K Antigen
AUTOR(ES)
Campbell, Gordon R. O.
FONTE
American Society for Microbiology
RESUMO
For Sinorhizobium meliloti (also known as Rhizobium meliloti) AK631 to establish effective symbiosis with alfalfa, it must be able to synthesize a symbiotically active form of its K antigen, a capsular polysaccharide containing a Kdo (3-deoxy-d-manno-octulosonic acid) derivative. Previously isolated mutants defective in the synthesis of K antigen are resistant to bacteriophage φ16-3. By screening ca. 100,000 Tn5-mutagenized R. meliloti bacteria for resistance to bacteriophage φ16-3, we isolated 119 mutants, 31 of which could not be complemented by genes previously identified as being required for K-antigen synthesis. Of these 31 new mutants, 13 were symbiotically defective and lacked the K antigen. Through genetic and phenotypic analyses, we have grouped these mutants into four distinct classes. Although all of these mutants lack the K antigen, many also have altered lipopolysaccharides (LPS), suggesting that the biochemical pathways for the synthesis of K antigen and LPS have common enzymatic steps. In addition, we have found that these and other classes of K-antigen-defective mutants of S. meliloti AK631 exhibit unique patterns of sensitivities to phage strains to which the parental strain was resistant. Our studies have identified new classes of genes required for both the synthesis of K antigen and the symbiotic proficiency of S. meliloti AK631. Some of these classes of genes also play a role in LPS synthesis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=107593Documentos Relacionados
- Striking Complexity of Lipopolysaccharide Defects in a Collection of Sinorhizobium meliloti Mutants
- Mutants of Rhizobium meliloti defective in succinate metabolism.
- Sinorhizobium fredii and Sinorhizobium meliloti Produce Structurally Conserved Lipopolysaccharides and Strain-Specific K Antigens
- Functional Analysis of Sinorhizobium meliloti Genes Involved in Biotin Synthesis and Transport
- Lipopolysaccharide mutants of Rhizobium meliloti are not defective in symbiosis.