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The product of the malE—lacZ gene fusion was reported to compete with some proteins including outer membrane lipoprotein in the protein translocation across the Echerichia coli membrane. The fusion product also inhibited colicin E1 export. Furthermore, globomycin, which accumulated prolipoprotein in the membrane, inhibited the translocation of colicin E1 in the wild-type cells, but not in lipoprotein-negative mutant cells. Since colicin E1 contains the internal signal-like sequence [Proc. Natl. Acad. Sci. USA (1982) 79, 2827–2831], these results suggest that colicin E1 is exported by the aid of this sequence at a common site for maltose-binding protein and lipoprotein translocation. 相似文献
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Abstract Staphylococcus carnosus TM300 is able to synthesize at least seven lipoproteins with molecular masses between 15 and 45 kDa; the proteins are located in the membrane fraction. It can be concluded that this strain also posesses the enzymes involved in lipoprotein modification and prolipoprotein signal peptidase (signal peptidase II) processing. The gene encoding the prolipoprotein signal peptidase, lsp , from Staphylococcus carnosus TM300 was cloned in Escherichia coli and sequenced. The deduced amino acid sequence of the Lsp showed amino acid similarities with the Lsp's of S. aureus , Enterobacter aerogenes, E. coli , and Pseudomonas fluorescens . The hydropathy profile reveals four hydrophobic segments which are homologous to the putative transmembrane regions of the E. coli signal peptidase II. E. coli strains carrying lsp of S. carnosus exhibited an increased globomycin resistance. 相似文献
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Danièle Cavard 《FEMS microbiology letters》1995,125(2-3):173-178
Abstract The total amount of the colicin A lysis protein produced by cells grown in rich medium was analysed by immunoblotting. The intermediate forms of synthesis of this small lipoprotein were present in the cells at any time of induction, confirming that processing and maturation of colicin A lysis protein are slow and incomplete processes. The level of these various forms varied according to the time of induction, the growth conditions, the producing strain and the plasmid carrying the cal gene. It depended mainly on the presence in the producing strain of a degP gene which encodes the DegP protease. According to growth conditions, the DegP protease hydrolysed either a part or the total amount of the acylated precursor form. In some cases, a protease(s) other than DegP seemed to act on either form(s) of the colicin A lysis protein. 相似文献
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Daniele Cavard S. Peter Howard Roland Lloubes Claude Lazdunski 《Molecular & general genetics : MGG》1989,217(2-3):511-519
Summary Two plasmids that overproduce the colicin A lysis protein, Cal, are described. Plasmid AT1 was constructed by a deletion in
the colicin A operon, which placed thecal gene near a truncatedcaa gene in such a way that both gene products were synthesized at high levels following induction. Plasmid Ck4 was constructed
by insertion of thecal gene downstream from thetac promoter of an expression vector. Overproduction of Cal was obtained after mitomycin C induction of pAT1 cells and after
IPTG induction of pCK4 cells. The kinetics of Cal synthesis were examined with [35S] methionine and [2-3H] glycerol inlpp orlpp
+ host strains. Each of the steps of the lipid modification and maturation pathway of Cal was demonstrated. The modified precursor
form of overproduced Cal was not chased as efficiently as when it is produced in pColA cells. After treatment with globomycin,
a significant amount of this modified precursor form accumulated and was degraded with time into smaller acylated proteins,
but without release of the signal peptide. Release of cellular proteins and quasi-lysis were observed after about 1 hour of
induction for cells containing either plasmid. In addition, in Cal-overproducing cells, the rate of quasi-lysis was increased
but not its extent. InpldA cells, quasi-lysis was reduced but not abolished. Lethality of the Cal induction in the overproducing cells was in the same
range as that in wild-type cells. 相似文献
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《Bioorganic & medicinal chemistry letters》2020,30(20):127419
Discovery of novel classes of Gram-negative antibiotics with activity against multi-drug resistant infections is a critical unmet need. As an essential member of the lipoprotein biosynthetic pathway, lipoprotein signal peptidase II (LspA) is an attractive target for antibacterial drug discovery, with the natural product inhibitor globomycin offering a modestly-active starting point. Informed by structure-based design, the globomycin depsipeptide was optimized to improve activity against E. coli. Backbone modifications, together with adjustment of physicochemical properties, afforded potent compounds with good in vivo pharmacokinetic profiles. Optimized compounds such as 51 (E. coli MIC 3.1 μM) and 61 (E. coli MIC 0.78 μM) demonstrate broad spectrum activity against gram-negative pathogens and may provide opportunities for future antibiotic discovery. 相似文献
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