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iTRAQ-coupled 2-D LC-MS/MS analysis of membrane protein profile in Escherichia coli incubated with apidaecin IB.

Zhou Y, Chen WN - PLoS ONE (2011)

Bottom Line: Cell division protease ftsH, an essential regulator in maintenance of membrane lipid homeostasis, was found to be overproduced in cells incubated with apidaecin IB.Its over-expression intensified the degradation of cytoplasmic protein UDP-3-O-acyl-N- acetylglucosamine deacetylase, which catalyzes the first committed step in the biosynthesis of the lipid A moiety of LPS, and thus leaded to the further unbalanced biosynthesis of LPS and phospholipids.Our findings suggested a new antibacterial mechanism of apidaecins and perhaps, by extension, for other proline-rich antimicrobial peptides.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical and Biomedical Engineering, College of Engineering, Nanyang Technological University, Singapore, Singapore.

ABSTRACT
Apidaecins are a series of proline-rich, 18- to 20-residue antimicrobial peptides produced by insects. They are predominantly active against the gram-negative bacteria. Previous studies mainly focused on the identification of their internal macromolecular targets, few addressed on the action of apidaecins on the molecules, especially proteins, of bacterial cell membrane. In this study, iTRAQ-coupled 2-D LC-MS/MS technique was utilized to identify altered membrane proteins of Escherichia coli cells incubated with one isoform of apidaecins--apidaecin IB. Cell division protease ftsH, an essential regulator in maintenance of membrane lipid homeostasis, was found to be overproduced in cells incubated with apidaecin IB. Its over-expression intensified the degradation of cytoplasmic protein UDP-3-O-acyl-N- acetylglucosamine deacetylase, which catalyzes the first committed step in the biosynthesis of the lipid A moiety of LPS, and thus leaded to the further unbalanced biosynthesis of LPS and phospholipids. Our findings suggested a new antibacterial mechanism of apidaecins and perhaps, by extension, for other proline-rich antimicrobial peptides.

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Western blot analysis of FtsH in E. coli incubated with apidaecin IB.The relative densitometric intensity of FtsH to RpoA in cells without incubation of apidaecin IB was adjusted to 1 and that in cells incubated with apidaecin IB was normalized accordingly. Asterisk indicates p<0.05.
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pone-0020442-g003: Western blot analysis of FtsH in E. coli incubated with apidaecin IB.The relative densitometric intensity of FtsH to RpoA in cells without incubation of apidaecin IB was adjusted to 1 and that in cells incubated with apidaecin IB was normalized accordingly. Asterisk indicates p<0.05.

Mentions: One of the altered membrane proteins, cell division protease ftsH, captured our attention. FtsH was overproduced in both 1 h and 2 h-apidaecin-incubated cells, with the increase in the latter was greater than that in the former (Table 1). The representative MS/MS spectra of peptides derived from FtsH are shown in Figure 2. The changes of FtsH were further validated by western blot analysis (Figure 3).


iTRAQ-coupled 2-D LC-MS/MS analysis of membrane protein profile in Escherichia coli incubated with apidaecin IB.

Zhou Y, Chen WN - PLoS ONE (2011)

Western blot analysis of FtsH in E. coli incubated with apidaecin IB.The relative densitometric intensity of FtsH to RpoA in cells without incubation of apidaecin IB was adjusted to 1 and that in cells incubated with apidaecin IB was normalized accordingly. Asterisk indicates p<0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105997&req=5

pone-0020442-g003: Western blot analysis of FtsH in E. coli incubated with apidaecin IB.The relative densitometric intensity of FtsH to RpoA in cells without incubation of apidaecin IB was adjusted to 1 and that in cells incubated with apidaecin IB was normalized accordingly. Asterisk indicates p<0.05.
Mentions: One of the altered membrane proteins, cell division protease ftsH, captured our attention. FtsH was overproduced in both 1 h and 2 h-apidaecin-incubated cells, with the increase in the latter was greater than that in the former (Table 1). The representative MS/MS spectra of peptides derived from FtsH are shown in Figure 2. The changes of FtsH were further validated by western blot analysis (Figure 3).

Bottom Line: Cell division protease ftsH, an essential regulator in maintenance of membrane lipid homeostasis, was found to be overproduced in cells incubated with apidaecin IB.Its over-expression intensified the degradation of cytoplasmic protein UDP-3-O-acyl-N- acetylglucosamine deacetylase, which catalyzes the first committed step in the biosynthesis of the lipid A moiety of LPS, and thus leaded to the further unbalanced biosynthesis of LPS and phospholipids.Our findings suggested a new antibacterial mechanism of apidaecins and perhaps, by extension, for other proline-rich antimicrobial peptides.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical and Biomedical Engineering, College of Engineering, Nanyang Technological University, Singapore, Singapore.

ABSTRACT
Apidaecins are a series of proline-rich, 18- to 20-residue antimicrobial peptides produced by insects. They are predominantly active against the gram-negative bacteria. Previous studies mainly focused on the identification of their internal macromolecular targets, few addressed on the action of apidaecins on the molecules, especially proteins, of bacterial cell membrane. In this study, iTRAQ-coupled 2-D LC-MS/MS technique was utilized to identify altered membrane proteins of Escherichia coli cells incubated with one isoform of apidaecins--apidaecin IB. Cell division protease ftsH, an essential regulator in maintenance of membrane lipid homeostasis, was found to be overproduced in cells incubated with apidaecin IB. Its over-expression intensified the degradation of cytoplasmic protein UDP-3-O-acyl-N- acetylglucosamine deacetylase, which catalyzes the first committed step in the biosynthesis of the lipid A moiety of LPS, and thus leaded to the further unbalanced biosynthesis of LPS and phospholipids. Our findings suggested a new antibacterial mechanism of apidaecins and perhaps, by extension, for other proline-rich antimicrobial peptides.

Show MeSH
Related in: MedlinePlus