Putrescine Importer PlaP Contributes to Swarming Motility and Urothelial Cell Invasion in Proteus mirabilis

Previously, we reported that the speA gene, encoding arginine decarboxylase, is required for swarming in the urinary tract pathogen Proteus mirabilis. In addition, this previous study suggested that putrescine may act as a cell-to-cell signaling molecule (Sturgill, G., and Rather, P. N. (2004) Mol. Microbiol. 51, 437-446). In this new study, PlaP, a putative putrescine importer, was characterized in P. mirabilis. In a wild-type background, a plaP null mutation resulted in a modest swarming defect and slightly decreased levels of intracellular putrescine. In a P. mirabilis speA mutant with greatly reduced levels of intracellular putrescine, plaP was required for the putrescine-dependent rescue of swarming motility. When a speA/plaP double mutant was grown in the presence of extracellular putrescine, the intracellular levels of putrescine were greatly reduced compared with the speA mutant alone, indicating that PlaP functioned as the primary putrescine importer. In urothelial cell invasion assays, a speA mutant exhibited a 50% reduction in invasion when compared with wild type, and this defect could be restored by putrescine in a PlaP-dependent manner. The putrescine analog Triamide-44 partially inhibited the uptake of putrescine by PlaP and decreased both putrescine stimulated swarming and urothelial cell invasion in a speA mutant

Anthracene-polyamine conjugates inhibit in vitro proliferation of intraerythrocytic Plasmodium falciparum parasites

Anthracene-polyamine conjugates inhibit the in vitro proliferation of the intraerythrocytic human malaria parasite, Plasmodium falciparum, with IC50 values in the nM-μM range. The compounds are taken up into the intraerythrocytic parasite where they arrest the parasite cell-cycle. Both the anthracene and polyamine components of the conjugates play a role in their antiplasmodial effect.JN was supported by the Carl and Emily Fuchs foundation, AusAID, the Ernst and Ethel Eriksen Trust, UP Mentorship Programme and the Claude Leon Foundation. This work was supported by the South African Medical Research Council, the South African National Research Foundation KISC programme (UID 67444), and the Australian National Health and Medical Research Council [Grant no. 525428 to KK].http://aac.asm.orghb201

Synthesis Of N-(Hydroxy)Amide- And N-(Hydroxy)Thioamide-Containing Peptides

Methods developed with N-(benzoyloxy)amines and hydroxamic acids were used in the synthesis of N-(hydroxy)amide-containing pseudopeptides. Acylation of N-(benzoyloxy)phenethylamine with the acid chloride of N(α)- Fmoc-L-leucine provided a N(α)-Fmoc-N-(benzoyloxy)-L-leucinamide in 90% yield. Deprotection of the benzoyl group (using 10 vol % NH4OH/MeOH) provided the N(α)-Fmoc-N-(hydroxy)-L-leucinamide in 87% yield. In general, the appended Fmoc group allowed for further elaboration of the N-hydroxy-N- (alkyl)amides using classic peptide-coupling methods. A practical synthetic strategy was developed, and racemization issues were addressed using diastereomeric Val-Leu derivatives. In addition, N-(hydroxy)thioamides were generated from the corresponding N-(benzoyloxy)thioamides. N- (Benzoyloxy)thioamides were obtained in moderate yields (53-76%) from the reaction of the corresponding N-(benzoyloxy)amides with Lawesson\u27s reagent (i.e., 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide). In summary, this new technology allows for the introduction of either N- hydroxyamide or N-(hydroxy)thioamide linkages into pseudopeptide chains without racemization

Total synthesis of acinetoferrin

The total synthesis of a novel siderophore, acinetoferrin, is described. The key transformation involves the tandem oxidation and acylation of the N3-amino group of N1-BOC propane diamine prior to coupling with the external carboxyls of citric acid. A \u27one-pot-two-step\u27 reaction converted a primary amine (RNH2) into a O-benzoyl hydroxamate (i.e., RN(OOCPh)COR\u27) in good yield (68%). These studies demonstrated the utility of the O-benzoyl protecting group in the synthesis of α,β-unsaturated hydroxamic acids

N-(Benzoyloxy)Amines: An Investigation Of Their Thermal Stability, Synthesis, And Incorporation Into Novel Peptide Constructs

A series of N-benzoyloxyamines were pyrolyzed and their decomposition temperatures correlated well with the amine architecture\u27s ability to stabilize a N-centered radical. A variety of amine substrates were treated with a biphasic mixture of benzoyl peroxide (BPO), CH2Cl2 and an aqueous carbonate buffer (at pH 10.5). Primary and secondary amines were successfully N-benzoyloxylated in good yield. Tertiary amines and BPO gave low yields of the corresponding N-oxide and complex product mixtures, presumably via radical decomposition. Electron deficient amines (such as fluorinated aliphatic amines, α-aminoacids, α-aminoesters, and α-aminoamides) were not N-benzoyloxylated under these conditions. Instead, N-benzoylation was observed with the fluorinated amines and the reaction was sensitive to temperature and the pH of the aqueous medium. A one-pot-two-step synthesis of Nα-FMOC-L-Leu-Nβ-(benzoyloxy)-β-alanine ethyl ester, a peptide containing both an α- and a novel β-amino acid framework, was also developed. © 2003 Elsevier Science Ltd. All rights reserved

N-(Benzoyloxy)amines: An Investigation of Their Thermal Stability, Synthesis, and Incorporation into Novel Peptide Constructs.

A series of N-benzoyloxyamines were pyrolyzed and their decomposition temperatures correlated well with the amine architecture\u27s ability to stabilize a N-centered radical. A variety of amine substrates were treated with a biphasic mixture of benzoyl peroxide (BPO), CH2Cl2 and an aqueous carbonate buffer (at pH 10.5). Primary and secondary amines were successfully N-benzoyloxylated in good yield. Tertiary amines and BPO gave low yields of the corresponding N-oxide and complex product mixtures, presumably via radical decomposition. Electron deficient amines (such as fluorinated aliphatic amines, α-aminoacids, α-aminoesters, and α-aminoamides) were not N-benzoyloxylated under these conditions. Instead, N-benzoylation was observed with the fluorinated amines and the reaction was sensitive to temperature and the pH of the aqueous medium. A one-pot-two-step synthesis of Nα-FMOC-L-Leu-Nβ-(benzoyloxy)-β-alanine ethyl ester, a peptide containing both an α- and a novel β-amino acid framework, was also developed. © 2003 Elsevier Science Ltd. All rights reserved

An Improved Synthesis of O-Benzoyl Protected Hydroxamates

Several primary amines (R-NH2) were converted to their corresponding O-benzoyl protected hydroxamates under biphasic conditions. The intermediate (benzoyloxy)amines (R-NHOCOPh) were generated using benzoyl peroxide dissolved in CH2Cl2 and an aqueous carbonate buffer (pH 10.5) at room temperature. Subsequent acylation with R\u27COCl gave the protected hydroxamates (R\u27CONROCOPh) in good overall yields (56-89%)

Chemoselective N-Acylation Via Condensations Of N-(Benzoyloxy)Amines And Α-Ketophosphonic Acids Under Aqueous Conditions

(Chemical Equation Presented) A new amide-forming reaction with N-benzoyloxyamines and α-ketophosphonic acids was investigated. A mixed solvent of t-BuOH/water (1:1) at 40°C provided the desired amide in high yield (71-96%). Both phosphonic acids (9, 12, or 13) and their disodium salts (e.g., 10) were shown to react with the respective N-benzoyloxyamines (1b and 4) in excellent yields. The phosphonic acid methyl ester monosodium salt 11 did not react under these conditions. However, compound 11 did provide the desired amide in 22% yield upon addition of 2 equiv of TFA. The N-acylation reaction is highly chemoselective for N-benzoyloxyamines as both aliphatic amines and N-hydroxylamines were shown not to react productively with the α-ketophosphonic acids under the conditions tested. Moreover, the α-ketophosphonic acids are more selective than the related α-ketocarboxylic acid systems, which react with both the N-hydroxylamines and N-benzoyloxyamines. In this regard, this novel phosphonic acid methodology provides a new high-yielding, chemoselective acylating reagent for further study. © 2008 American Chemical Society