Disease relevance of lpsB

• 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 [1].
• The lpcC gene of Rhizobium leguminosarum and the lpsB gene of Sinorhizobium meliloti encode protein orthologs that are 58% identical over their entire lengths of about 350 amino acid residues [2].
• Expression of lpsB in E. coli using a T7lac promoter-driven construct results in the appearance of similar multiple glycosyl transferase activities seen in S. meliloti 2011 membranes [2].
• The genetic characterization of a 5.5-kb chromosomal region of Sinorhizobium meliloti 2011 that contains lpsB, a gene required for the normal development of symbiosis with Medicago spp., is presented [3].

High impact information on lpsB

• 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 [1].
• This complex pattern of glycosylation is due entirely to LpsB, since membranes of the S. meliloti lpsB mutant 6963 do not glycosylate Kdo(2)-[4'-(32)P]lipid IV(A) in the presence of any of these sugar nucleotides [2].
• In addition, an S. meliloti lpsB mutant that is defective at a stage in infection of the host similar to that found for a bacA mutant is also sensitive to the same agents, and the carbohydrate content of its lipopolysaccharide (LPS) is altered [4].
• The opposite orientation of lpsB with respect to its first downstream coding sequence, lpsE, indicated that the altered LPS and the defective symbiosis of lpsB mutants are both consequences of a primary nonpolar defect in a single gene [3].
• The functional relationship between these two genes was demonstrated in genetic complementation experiments in which the S. meliloti lpsB gene restored the wild-type LPS phenotype when introduced into lpcC mutants of R. leguminosarum [3].

Biological context of lpsB

• Except for lpsB, none of the lps genes were relevant for nodulation and nitrogen fixation [3].
• Mutants in the four best-characterized groups (class A, lpsB, lpsC, and class D), which map to the rhizobial chromosome, appear to affect lipopolysaccharide (LPS) as judged by the reactivity with monoclonal antibodies and behavior on sodium dodecyl sulfate-polyacrylamide gels of extracted LPS [5].

References