ABSTRACT
The LolCDE complex is an ATP-binding cassette transporter that mediates the release of newly synthesized lipoproteins from the cytoplasmic membrane of gram-negative bacteria, which results in the initiation of outer-membrane sorting of lipoproteins through the Lol pathway. LolCDE is composed of one copy each of membrane subunits LolC and LolE, and two copies of nucleotide-binding subunit LolD. In this study, we examined the membrane topology of LolC and LolE by PhoA fusion analysis. Both LolC and LolE were found to have four transmembrane segments with a large periplasmic loop exposed to the periplasm. Despite similarities in sequence and topology, the accessibility of a sulfhydryl reagent to Cys introduced into the periplasmic loop suggested that the structure of the periplasmic region differs between LolC and LolE. Inhibition of the release of lipoproteins by the sulfhydryl reagent supported a previous proposal that LolC and LolE have distinct functions.
Subject(s)
ATP-Binding Cassette Transporters/metabolism , Cell Membrane/chemistry , Cell Membrane/metabolism , Escherichia coli Proteins/metabolism , Periplasm/metabolism , ATP-Binding Cassette Transporters/chemistry , Amino Acid Sequence , Cysteine/metabolism , Escherichia coli Proteins/chemistry , Lipoproteins/metabolism , Molecular Sequence Data , Periplasm/chemistry , Sulfonic Acids/chemistry , Sulfonic Acids/metabolismABSTRACT
Since factor Xa (fXa) plays a pivotal role in the blood coagulation cascade, inhibition of fXa is thought to be an effective treatment for a variety of thrombotic events. (2S)-2-[4-[[(3S)-1-Acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3-(7-amidino-2-naphthyl)propanoic acid hydrochloride pentahydrate (DX-9065a) was previously found in our laboratory as a novel orally active factor Xa inhibitor. DX-9065a exhibits a strong inhibitory activity toward fXa by occupying the substrate recognition (called S1) sites and aryl binding sites of fXa. Herein we describe conversions of the amidinonaphthalene and the acetimidoylpyrrolidine moieties of DX-9065a. Some compounds showed remarkably increased in vitro anti-factor Xa and PRCT activities compared with those of DX-9065a. The most promising compound 38 showed four times the prolongation of APTT against DX-9065a after oral administration to rats.
