Disease relevance of tolA

• tolA mutants of Escherichia coli K-12 release periplasmic proteins into the extracellular medium; they are sensitive to growth inhibitors such as cholic acid and tolerant to group A colicins and filamentous bacteriophage [1].
• The exc, lky and tol mutations mapped near the gal operon at min 16.5 of the E. coli linkage map [2].
• In addition, genes specific to E. coli were also studied: ompA, ompFand tolA (predicting epigenetic variation that could help escape infection by phages or colicins) [3].
• In this work, delta tolA and delta pal mutants of E. coli K-12 W3110 were transformed with pMF19 (encoding a rhamnosyltransferase that reconstitutes the expression of O16-specific LPS), pWQ5 (encoding the Klebsiella pneumoniae O1 LPS gene cluster), or pWQ802 (encoding the genes necessary for the synthesis of Salmonella enterica O:54) [4].
• A recent survey of gene expression in Pseudomonas aeruginosa biofilms has identified tolA as a gene activated in biofilms [5].

High impact information on tolA

• In contrast, a polar tolQ mutation affecting tolA expression in VW187 caused slow growth rate and serum sensitivity in addition to reduced O7 LPS production [6].
• All these phenotypes were corrected upon complementation with cloned tol genes but were not restored by complementation with the tolQRA operon containing the frameshift mutation in tolA [6].
• The O7-deficient phenotype in the tolQ and tolA mutants was complemented with a plasmid encoding the tolQRA operon, but not with a similar plasmid containing a frameshift mutation inactivating tolA [6].
• Furthermore, we show that the reduced surface expression of O16 LPS in delta tolA and delta pal mutants was associated with a partial defect in O-antigen polymerization and it was corrected by complementation with intact tolA and pal genes, respectively [4].
• Genetic suppression experiments were performed to restore the functional activity of some tolA mutants [7].

Biological context of tolA

• The phenotype resulting from an insertion of the chloramphenicol gene into the gene coding for the 142-amino acid protein is identical to that of mutations in fii and tolA [8].
• Therefore, the reduction in O7 LPS was attributed to the lack of a functional tolA gene, caused either by a direct mutation of this gene or by a polar effect on tolA gene expression exerted by the tolQ mutation [6].
• The nucleotide sequence of a 2.8-kilobase fragment containing the tolA and tolB genes was determined [9].
• Impairment of cell division in tolA mutants of Escherichia coli at low and high medium osmolarities [10].
• In the presence of the phoS2333 mutation, F- lky strains lysogenized with phi 80 phoBin phoA+ phage and grown in high phosphate medium were able to release eight times more APase activity (2300 units ml-1) than haploid strain 2336 (phoS+ lky) grown in low phosphate medium [11].

Anatomical context of tolA

• The presence of the free carboxyl-terminal domain of TolA in the periplasm in a tolA null mutation did not restore the wild-type phenotype, suggesting that this domain must be part of the intact TolA molecule to perform its function [12].

Other interactions of tolA

• The TolA protein is involved in maintaining the integrity of the outer membrane of Escherichia coli, as mutations in tolA cause the bacteria to become hypersensitive to detergents and certain antibiotics and to leak periplasmic proteins into the medium [12].

Analytical, diagnostic and therapeutic context of tolA

• Our observations by confocal and electron microscopy have revealed that tolA mutants show modified morphology and produce DNA-free cells [10].

References