Formate protects stationary‐phase <i>Escherichia coli</i> and <i>Salmonella</i> cells from killing by a cationic antimicrobial peptide

Barker, Helen; Kinsella, Niamh; Jaspe, A.; Friedrich, Thorsten; O’Connor, C. David

doi:10.1046/j.1365-2958.2000.01820.x

Cited by 56 publications

(70 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Expression effects mediated by formate could be involved in the phenomenon of formate protection from antimicrobial peptides (7). The absence of RpoS participation in formate protection is consistent with our finding of lowered steadystate activity of the RpoS regulon in cultures grown with formate.…”

Section: Discussionsupporting

confidence: 90%

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli

et al. 2001

View full text Add to dashboard Cite

Acetate and formate are major fermentation products of Escherichia coli. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth. E. coli W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Acetate increased the steady-state expression levels of 37 proteins, including periplasmic transporters for amino acids and peptides (ArtI, FliY, OppA, and ProX), metabolic enzymes (YfiD and GatY), the RpoS growth phase regulon, and the autoinducer synthesis protein LuxS. Acetate repressed 17 proteins, among them phosphotransferase (Pta). An ackA-pta deletion, which nearly eliminates interconversion between acetate and acetyl-coenzyme A (acetyl-CoA), led to elevated basal levels of 16 of the acetate-inducible proteins, including the RpoS regulon. Consistent with RpoS activation, the ackA-pta strain also showed constitutive extreme-acid resistance. Formate, however, repressed 10 of the acetate-inducible proteins, including the RpoS regulon. Ten of the proteins with elevated basal levels in the ackA-pta strain were repressed by growth of the mutant with formate; thus, the formate response took precedence over the loss of the ackA-pta pathway. The similar effects of exogenous acetate and the ackA-pta deletion, and the opposite effect of formate, could have several causes; one possibility is that the excess buildup of acetyl-CoA upregulates stress proteins but excess formate depletes acetyl-CoA and downregulates these proteins.

show abstract

Section: Discussionsupporting

confidence: 90%

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli

et al. 2001

View full text Add to dashboard Cite

show abstract

“…However, the fact that only adhC1 is iron regulated may suggest that the product of this gene plays a role additional to its well-established function in the detoxification of intracellular formaldehyde. It was recently reported that organic acids such as formate, which is produced by the successive enzymic action of GSH-FDH and S-formylglutathione hydrolase on formaldehyde, protect stationary-phase E. coli and Salmonella cells from killing by cationic peptides (Barker et al, 2000). Thus, a potential protective function of increased expression of GSH-FDH, which would result in higher intracellular levels of formate, is in agreement with the fact that pathogens such as A. baumannii encounter antimicrobial peptides produced by the host.…”

Section: Discussionmentioning

confidence: 99%

Acinetobacter baumannii has two genes encoding glutathione-dependent formaldehyde dehydrogenase: evidence for differential regulation in response to iron This paper is dedicated to the memory of Dr M. A. Vides, Facultad de Ciencias Quı́micas, Universidad Nacional de Córdoba, Argentina, who was a great mentor and colleague. The GenBank accession number for the sequence reported in this paper is AF130307.

et al. 2001

View full text Add to dashboard Cite

The adhC1 gene from Acinetobacter baumannii 8399, which encodes a glutathione-dependent formaldehyde dehydrogenase (GSH-FDH), was identified and cloned after mapping the insertion site of Tn3-HoHo1 in a recombinant cosmid isolated from a gene library. Sequence analysis showed that this gene encodes a protein exhibiting significant similarity to alcohol dehydrogenases in bacterial, yeast, plant and animal cells. The expression of the adhC1 gene was confirmed by the detection of GSH-FDH enzyme activity in A. baumannii and Escherichia coli cells that expressed the cloned gene. However, the construction and analysis of an A. baumannii 8399 adhC1 ::Tn3-HoHo1 isogenic derivative revealed the presence of adhC2, a second copy of the gene encoding GSH-FDH activity. Enzyme assays and immunoblot analysis showed that adhC2 encodes a 465 kDa protein that is produced in similar amounts under iron-rich and iron-limited conditions. In contrast, the expression of adhC1, which encodes a 45 kDa protein with GSH-FDH activity, is induced under iron limitation and repressed when the cells are cultured in the presence of free inorganic iron. The differential expression of adhC1 is controlled at the transcriptional level and mediated through the Fur ironrepressor protein, which has potential binding sites within the promoter region of this adhC copy. The expression of both adhC copies is significantly enhanced by the presence of sub-inhibitory concentrations of formaldehyde in the culture media. Examination of different A. baumannii isolates indicates that they can be divided into two groups based on the type of GSH-FDH they produce. One group contains only the constitutively expressed 465 kDa protein, whilst the other produces this GSH-FDH type in addition to the ironregulated isoenzyme. Further analysis showed that the presence and expression of the two adhC genes does not confer resistance to exogenous formaldehyde, nor does it enable it to utilize methylated compounds as a sole carbon source when cultured under iron-rich as well as iron-deficient conditions.

show abstract

“…This region forms an amphipathic beta-turn and binds LPS (14,28). It has been proposed that BPI and P2, a peptide that contains BPI residues 86 to 104, may employ the same mechanism for killing Escherichia coli since both increase outer membrane (OM) permeability to hydrophobic compounds and inhibit O 2 consumption (2,21). The cytotoxic mechanism of BPI remains poorly understood.…”

mentioning

confidence: 99%

“…The released divalent ions are thought to activate bacterial phospholipases, leading to membrane rupture (26,29). It is also thought that BPI may damage the cytoplasmic membranes of the target cells (2,21,30).…”

mentioning

confidence: 99%

See 1 more Smart Citation

TheVibrio choleraeToxR-Regulated Porin OmpU Confers Resistance to Antimicrobial Peptides

2004

View full text Add to dashboard Cite

BPI (bactericidal/permeability-increasing) is a potent antimicrobial protein that was recently reported to be expressed as a surface protein on human gastrointestinal tract epithelial cells. In this study, we investigated the resistance of Vibrio cholerae, a small-bowel pathogen that causes cholera, to a BPI-derived peptide, P2. Unlike in Escherichia coli and Salmonella enterica serovar Typhimurium, resistance to P2 in V. cholerae was not dependent on the BipA GTPase. Instead, we found that ToxR, the master regulator of V. cholerae pathogenicity, controlled resistance to P2 by regulating the production of the outer membrane protein OmpU. Both toxR and ompU mutants were at least 100-fold more sensitive to P2 than were wild-type cells. OmpU also conferred resistance to polymyxin B sulfate, suggesting that this porin may impart resistance to cationic antibacterial proteins via a common mechanism. Studies of stationary-phase cells revealed that the ToxR-repressed porin OmpT may also contribute to P2 resistance. Finally, although the mechanism of porin-mediated resistance to antimicrobial peptides remains elusive, our data suggest that the BPI peptide sensitivity of OmpU-deficient V. cholerae is not attributable to a generally defective outer membrane.

show abstract

Formate protects stationary‐phase Escherichia coli and Salmonella cells from killing by a cationic antimicrobial peptide

Cited by 56 publications

References 47 publications

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli

TheVibrio choleraeToxR-Regulated Porin OmpU Confers Resistance to Antimicrobial Peptides

Contact Info

Product

Resources

About