A Putative Gene Cluster for Aminoarabinose Biosynthesis Is Essential for Burkholderia cenocepacia Viability

Abstract

Using a conditional mutagenesis strategy we demonstrate here that a gene cluster encoding putative aminoarabinose (Ara4N) biosynthesis enzymes is essential for the viability of Burkholderia cenocepacia. Loss of viability is associated with dramatic changes in bacterial cell morphology and ultrastructure, increased permeability to propidium iodide, and sensitivity to sodium dodecyl sulfate, suggesting a general cell envelope defect caused by the lack of Ara4N.

Mechanisms of intrinsic resistance to antimicrobial peptides of Edwardsiella ictaluri and its influence on fish gut inflammation and virulence

“…In Burkholderia cepacia, L-Ara4N is constitutively incorporated into both lipid A and LPS core oligosaccharide (Silipo et al, 2005). Some evidence suggests that this is also true in B. cenocepacia, where UDP-L-Ara4N synthesis is essential for viability (Ortega et al, 2007). These observations highlight the importance of L-Ara4N in membrane…”

Contributions of two UDP-glucose dehydrogenases to viability and polymyxin B resistance of Burkholderia cenocepacia

“…In B. cepacia, a species closely related to B. cenocepacia, Ara4N is constitutively incorporated into both lipid A and the LPS core oligosaccharide (Silipo et al, 2005). Preliminary evidence suggests that this is also true in B. cenocepacia (X. P. Ortega & M. A. Valvano, unpublished data) and UDPAra4N synthesis was recently shown to be essential for B. cenocepacia viability (Ortega et al, 2007). These results highlight the importance of Ara4N in this organism and its abundance in LPS likely contributes significantly to the organism's unusually high AP resistance.…”

“…Triplicate 300 ml aliquots of the cells with either vehicle control or the various concentrations of pmB were incubated in the Bioscreen C automated growth curve reader, as described above, for 18 h. MIC 50 values reported are the mode of three independent experiments. An assay for growth of conditional mutants was performed as previously described (Ortega et al, 2007). Expression of putative essential genes was repressed with 1.0 % (w/v) glucose and induced with 1.0 % (w/v) rhamnose.…”

“…These plasmids were transferred into SAL23, resulting in strains SAL25 (conditional hldA) and SAL26 (conditional ugd BCAL2946 ). A conditional ugd BCAL2946 mutant in the K56-2 background (SAL10), also constructed with pSL27, was previously described (Ortega et al, 2007).…”

“…Plasmids for the conditional mutagenesis of hldA and ugd BCAL2946 were constructed as described above with fragments corresponding to the 59 ends of the two genes cloned into the plasmid pSC201 (Ortega et al, 2007), resulting in plasmids pSL26 (hldA) and pSL27 (ugd BCAL2946 ). These plasmids were transferred into SAL23, resulting in strains SAL25 (conditional hldA) and SAL26 (conditional ugd BCAL2946 ).…”