Modulations in lipid A and phospholipid biosynthesis pathways influence outer membrane protein assembly in Escherichia coli K-12
Abstract
The assembly defect of a mutant outer membrane protein, OmpF315, can be corrected by suppressor mutations that lower lipopolysaccharide (LPS) levels and indirectly elevate phospholipid levels. One such assembly suppressor mutation, asmB1, is an allele of lpxC (envA) whose product catalyses the first rate-limiting step in the lipid A (LPS) biosynthesis pathway. Besides reducing LPS levels, asmB1 confers sensitivity to MacConkey medium. A mutation, sabA1, that reverses the MacConkey sensitivity phenotype of asmB1 maps within fabZ (whose product is needed for phospholipid synthesis from a precursor) is also required for lipid A synthesis. In addition to reversing MacConkey sensitivity, the sabA1 mutation reverses the OmpF315 assembly suppression phenotype of asmB1. These results show that OmpF315 assembly suppression by asmB1, which is achieved by lowering LPS levels, can be averted by a subsequent aberration in phospholipid synthesis at a point where the biosynthetic pathways for these two lipid molecules split. OmpF315 assembly suppression can also be achieved in an asmB+ background where FabZ expression is increased. The data obtained in this study provide genetic evidence that elevated phospholipid levels and/or phospholipid t...Continue Reading
References
OmpF assembly mutants of Escherichia coli K-12: isolation, characterization, and suppressor analysis
A periplasmic protein (Skp) of Escherichia coli selectively binds a class of outer membrane proteins
Citations
Identification and characterization of inhibitors of bacterial enoyl-acyl carrier protein reductase.
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