Regulation of polymyxin resistance and adaptation to low-Mg2+ environments

Groisman, Eduardo A.; Kayser, Jason; Soncini, Fernando C.

doi:10.1128/jb.179.22.7040-7045.1997

Cited by 248 publications

(280 citation statements)

References 52 publications

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“…Magnesium is also required to make ATP biologically active and participates in catalysis of certain enzymatic reactions through either direct or indirect mechanisms (14,15). Almost half of total magnesium is found associated with nucleoside triphosphates (NTPs) (primarily ATP) (11), approximately one-third is associated with the cell wall (13), and the remaining is bound to various molecules or free in the cytoplasm. Almost a quarter of this cytoplasmic magnesium is a Mutants were grown in buffered tryptone broth supplemented with 0.4% glucose alone or with 1 mM MgSO 4 for 10 h. Biomass increase was determined by OD 600 measurements.…”

Section: Discussionmentioning

confidence: 99%

“…In Gram-negative bacteria such as E. coli, magnesium is involved in stabilization of membrane phospholipids, lipopolysaccharide, polyphosphate compounds like DNA and RNA, and the ribosome (11)(12)(13). Magnesium is also required to make ATP biologically active and participates in catalysis of certain enzymatic reactions through either direct or indirect mechanisms (14,15).…”

Section: Discussionmentioning

confidence: 99%

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Increasing Growth Yield and Decreasing Acetylation in Escherichia coli by Optimizing the Carbon-to-Magnesium Ratio in Peptide-Based Media

Christensen

Orr

Rao

et al. 2017

Appl Environ Microbiol

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Complex media are routinely used to cultivate diverse bacteria. However, this complexity can obscure the factors that govern cell growth. While studying protein acetylation in buffered tryptone broth supplemented with glucose (TB7-glucose), we observed that Escherichia coli did not fully consume glucose prior to stationary phase. However, when we supplemented this medium with magnesium, the glucose was completely consumed during exponential growth, with concomitant increases in cell number and biomass but reduced cell size. Similar results were observed with other sugars and other peptide-based media, including lysogeny broth. Magnesium also limited cell growth for Vibrio fischeri and Bacillus subtilis in TB7-glucose. Finally, magnesium supplementation reduced protein acetylation. Based on these results, we conclude that growth in peptide-based media is magnesium limited. We further conclude that magnesium supplementation can be used to tune protein acetylation without genetic manipulation. These results have the potential to reduce potentially deleterious acetylated isoforms of recombinant proteins without negatively affecting cell growth.IMPORTANCE Bacteria are often grown in complex media. These media are thought to provide the nutrients necessary to grow bacteria to high cell densities. In this work, we found that peptide-based media containing a sugar are magnesium limited for bacterial growth. In particular, magnesium supplementation is necessary for the bacteria to use the sugar for cell growth. Interestingly, in the absence of magnesium supplementation, the bacteria still consume the sugar. However, rather than use it for cell growth, the bacteria instead use the sugar to acetylate lysines on proteins. As lysine acetylation may alter the activity of proteins, this work demonstrates how lysine acetylation can be tuned through magnesium supplementation. These findings may be useful for recombinant protein production, when acetylated isoforms are to be avoided. They also demonstrate how to increase bacterial growth in complex media.KEYWORDS acetylation, complex media, improved cell growth, magnesium, tryptone B acteria are routinely grown in complex media containing a rich assortment of nutrients. For example, lysogeny broth (LB) contains tryptone and yeast exact. Together, these components provide a rich mixture of nutrients that supports growth of numerous bacteria. However, the complexity of such media obscures factors governing cell behavior, especially those that limit cell growth.We routinely grow Escherichia coli aerobically in buffered tryptone broth (TB7) supplemented with 4 g/liter glucose (TB7-glucose) when studying protein acetylation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Increasing Growth Yield and Decreasing Acetylation in Escherichia coli by Optimizing the Carbon-to-Magnesium Ratio in Peptide-Based Media

Christensen

Orr

Rao

et al. 2017

Appl Environ Microbiol

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“…2B and Table 2. The pmr designations (11,12,16) were originally used to describe genes required for the maintenance of polymyxin resistance in S. typhimurium (Fig. 2B).…”

Section: Methodsmentioning

confidence: 99%

An Undecaprenyl Phosphate-Aminoarabinose Flippase Required for Polymyxin Resistance in Escherichia coli

Yan¹,

Guan²,

Raetz

2007

Journal of Biological Chemistry

132

136

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Modification of lipid A with the 4-amino-4-deoxy-L-arabinose (L-Ara4N) moiety is required for resistance to polymyxin and cationic antimicrobial peptides in Escherichia coli and Salmonella typhimurium. An operon of seven genes (designated pmrHFIJKLM in S. typhimurium), which is regulated by the PmrA transcription factor and is also present in E. coli, is necessary for the maintenance of polymyxin resistance. We previously elucidated the roles of pmrHFIJK in the biosynthesis and attachment of L-Ara4N to lipid A and renamed these genes arn-BCADT, respectively. We now propose functions for the last two genes of the operon, pmrL and pmrM. Chromosomal inactivation of each of these genes in an E. coli pmrA c parent switched its phenotype from polymyxin-resistant to polymyxin-sensitive. The lipid A moiety of lipopolysaccharide (LPS) 4 in the outer membranes of Gram-negative bacteria typically consists of a ␤,1Ј-6-linked disaccharide of glucosamine, modified with phosphate groups at the 1-and 4Ј-positions, and with R-3-hydroxyacyl chains at the 2-, 3-, 2Ј-, and 3Ј-positions (Fig.

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“…Resistance to PMB induced by the PmrA-PmrB regulatory system is well studied in Salmonella enterica serovar Typhimurium (Gunn & Miller, 1996;Groisman et al, 1997;Gunn et al, 1998;Zhou et al, 2001). This system is a part of the signal transduction network PhoP-PhoQ, which controls a plethora of virulence factors including modifications of LPS (Groisman, 2001).…”

Section: Introductionmentioning

confidence: 99%

Phosphoethanolamine substitution in the lipid A of Escherichia coli O157 : H7 and its association with PmrC

et al. 2006

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This study shows that lipid A of Escherichia coli O157 : H7 differs from that of E. coli K-12 in that it has a phosphoform at the C-1 position, which is distinctively modified by a phosphoethanolamine (PEtN) moiety, in addition to the diphosphoryl form. The pmrC gene responsible for the addition of PEtN to the lipid A of E. coli O157 : H7 was inactivated and the changes in lipid A profiles were assessed. The pmrC null mutant still produced PEtN-modified lipid A species, albeit in a reduced amount, indicating that PmrC was not the only enzyme that could be used to add PEtN to lipid A. Natural PEtN substitution was shown to be present in the lipid A of other serotypes of enterohaemorrhagic E. coli and absent from the lipid A of E. coli K-12. However, the cloned pmrC O157 gene in a high-copy-number plasmid generated a large amount of PEtN-substituted lipid A species in E. coli K-12. The occurrence of PEtN-substituted lipid A species was associated with a slight increase in the MICs of cationic peptide antibiotics, suggesting that the lipid A modification with PEtN would be beneficial for survival of E. coli O157 : H7 in certain environmental niches. However, PEtN substitution in the lipid A profiles was not detected when putative inner-membrane proteins (YhbX/YbiP/YijP/Ecf3) that show significant similarity with PmrC in amino acid sequence were expressed from high-copy-number plasmids in E. coli K-12. This suggests that these potential homologues are not responsible for the addition of PEtN to lipid A in the pmrC mutant of E. coli O157 : H7. When cells were treated with EDTA, the amount of palmitoylated lipid A from the cells carrying a high-copy-number plasmid clone of pmrC O157 that resulted in significant increase of PEtN substitution was unchanged compared with cells without PEtN substitution, suggesting that the PEtN moiety substituted in lipid A does not compensate for the loss of divalent cations required for bridging neighbouring lipid A molecules.

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Regulation of polymyxin resistance and adaptation to low-Mg2+ environments

Cited by 248 publications

References 52 publications

Increasing Growth Yield and Decreasing Acetylation in Escherichia coli by Optimizing the Carbon-to-Magnesium Ratio in Peptide-Based Media

Increasing Growth Yield and Decreasing Acetylation in Escherichia coli by Optimizing the Carbon-to-Magnesium Ratio in Peptide-Based Media

An Undecaprenyl Phosphate-Aminoarabinose Flippase Required for Polymyxin Resistance in Escherichia coli

Phosphoethanolamine substitution in the lipid A of Escherichia coli O157 : H7 and its association with PmrC

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