<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Lienkamp, Karen</style></author><author><style face="normal" font="default" size="100%">Madkour, Ahmad E</style></author><author><style face="normal" font="default" size="100%">Kumar, Kushi-Nidhi</style></author><author><style face="normal" font="default" size="100%">Nüsslein, Klaus</style></author><author><style face="normal" font="default" size="100%">Tew, Gregory N</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Antimicrobial polymers prepared by ring-opening metathesis polymerization: manipulating antimicrobial properties by organic counterion and charge density variation.</style></title><secondary-title><style face="normal" font="default" size="100%">Chemistry</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Chemistry</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Anti-Infective Agents</style></keyword><keyword><style  face="normal" font="default" size="100%">Biomimetic Materials</style></keyword><keyword><style  face="normal" font="default" size="100%">Cations</style></keyword><keyword><style  face="normal" font="default" size="100%">Diamines</style></keyword><keyword><style  face="normal" font="default" size="100%">Hemolysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrophobic and Hydrophilic Interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">Microbial Sensitivity Tests</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymers</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2009 Nov 2</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">15</style></volume><pages><style face="normal" font="default" size="100%">11715-22</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The synthesis and characterization of a series of poly(oxanorbornene)-based synthetic mimics of antimicrobial peptides (SMAMPs) is presented. In the first part, the effect of different organic counterions on the antimicrobial properties of the SMAMPs was investigated. Unexpectedly, adding hydrophobicity by complete anion exchange did not increase the SMAMPs' antimicrobial activity. It was found by dye-leakage studies that this was due to the loss of membrane activity of these polymers caused by the formation of tight ion pairs between the organic counterions and the polymer backbone. In the second part, the effect of molecular charge density on the biological properties of a SMAMP was investigated. The results suggest that, above a certain charge threshold, neither minimum inhibitory concentration (MIC90) nor hemolytic activity (HC50) is greatly affected by adding more cationic groups to the molecule. A SMAMP with an MIC90 of 4 microg mL(-1) against Staphylococcus aureus and a selectivity (=HC50/MIC90) of 650 was discovered, the most selective SMAMP to date.</style></abstract><issue><style face="normal" font="default" size="100%">43</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/19798715?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Lienkamp, Karen</style></author><author><style face="normal" font="default" size="100%">Madkour, Ahmad E</style></author><author><style face="normal" font="default" size="100%">Musante, Ashlan</style></author><author><style face="normal" font="default" size="100%">Nelson, Christopher F</style></author><author><style face="normal" font="default" size="100%">Nüsslein, Klaus</style></author><author><style face="normal" font="default" size="100%">Tew, Gregory N</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Antimicrobial polymers prepared by ROMP with unprecedented selectivity: a molecular construction kit approach.</style></title><secondary-title><style face="normal" font="default" size="100%">J Am Chem Soc</style></secondary-title><alt-title><style face="normal" font="default" size="100%">J. Am. Chem. Soc.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Anti-Infective Agents</style></keyword><keyword><style  face="normal" font="default" size="100%">Antimicrobial Cationic Peptides</style></keyword><keyword><style  face="normal" font="default" size="100%">Biomimetic Materials</style></keyword><keyword><style  face="normal" font="default" size="100%">Erythrocytes</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli</style></keyword><keyword><style  face="normal" font="default" size="100%">Hemolysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrophobic and Hydrophilic Interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">Microbial Sensitivity Tests</style></keyword><keyword><style  face="normal" font="default" size="100%">Molecular Weight</style></keyword><keyword><style  face="normal" font="default" size="100%">Norbornanes</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymers</style></keyword><keyword><style  face="normal" font="default" size="100%">Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization</style></keyword><keyword><style  face="normal" font="default" size="100%">Staphylococcus aureus</style></keyword><keyword><style  face="normal" font="default" size="100%">Structure-Activity Relationship</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2008 Jul 30</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">130</style></volume><pages><style face="normal" font="default" size="100%">9836-43</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Synthetic Mimics of Antimicrobial Peptides (SMAMPs) imitate natural host-defense peptides, a vital component of the body's immune system. This work presents a molecular construction kit that allows the easy and versatile synthesis of a broad variety of facially amphiphilic oxanorbornene-derived monomers. Their ring-opening metathesis polymerization (ROMP) and deprotection provide several series of SMAMPs. Using amphiphilicity, monomer feed ratio, and molecular weight as parameters, polymers with 533 times higher selectivitiy (selecitviy = hemolytic concentration/minimum inhibitory concentration) for bacteria over mammalian cells were discovered. Some of these polymers were 50 times more selective for Gram-positive over Gram-negative bacteria while other polymers surprisingly showed the opposite preference. This kind of &quot;double selectivity&quot; (bacteria over mammalian and one bacterial type over another) is unprecedented in other polymer systems and is attributed to the monomer's facial amphiphilicity.</style></abstract><issue><style face="normal" font="default" size="100%">30</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/18593128?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Griffith, Kevin L</style></author><author><style face="normal" font="default" size="100%">Wolf, Richard E</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A comprehensive alanine scanning mutagenesis of the Escherichia coli transcriptional activator SoxS: identifying amino acids important for DNA binding and transcription activation.</style></title><secondary-title><style face="normal" font="default" size="100%">J Mol Biol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">J. Mol. Biol.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Alanine</style></keyword><keyword><style  face="normal" font="default" size="100%">Amino Acid Substitution</style></keyword><keyword><style  face="normal" font="default" size="100%">Base Sequence</style></keyword><keyword><style  face="normal" font="default" size="100%">Binding Sites</style></keyword><keyword><style  face="normal" font="default" size="100%">DNA</style></keyword><keyword><style  face="normal" font="default" size="100%">DNA-Binding Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Electrophoretic Mobility Shift Assay</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Gene Expression Regulation, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Genes, Lethal</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrophobic and Hydrophilic Interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">Lac Operon</style></keyword><keyword><style  face="normal" font="default" size="100%">Models, Molecular</style></keyword><keyword><style  face="normal" font="default" size="100%">Mutagenesis</style></keyword><keyword><style  face="normal" font="default" size="100%">Nucleic Acid Conformation</style></keyword><keyword><style  face="normal" font="default" size="100%">Phenotype</style></keyword><keyword><style  face="normal" font="default" size="100%">Phosphates</style></keyword><keyword><style  face="normal" font="default" size="100%">Promoter Regions, Genetic</style></keyword><keyword><style  face="normal" font="default" size="100%">Protein Binding</style></keyword><keyword><style  face="normal" font="default" size="100%">Protein Structure, Tertiary</style></keyword><keyword><style  face="normal" font="default" size="100%">Structure-Activity Relationship</style></keyword><keyword><style  face="normal" font="default" size="100%">Trans-Activators</style></keyword><keyword><style  face="normal" font="default" size="100%">Transcriptional Activation</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2002 Sep 13</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">322</style></volume><pages><style face="normal" font="default" size="100%">237-57</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">SoxS is the direct transcriptional activator of the superoxide regulon. SoxS recognizes a highly degenerate &quot;soxbox&quot; DNA sequence, and activates transcription from class I and class II promoters. SoxS is the smallest member of the AraC/XylS family of transcription regulators whose hallmark is dual helix-turn-helix (HTH) DNA-binding motifs. Evidence suggests that the N-terminal HTH motif of SoxS interacts with a highly conserved region of the soxbox termed recognition element 1 (RE1), while the C-terminal HTH motif interacts with the less conserved recognition element 2 (RE2). In the work described here, we prepared a complete library of 101 SoxS mutants containing single alanine substitutions of SoxS, and we characterized the mutant proteins in vivo and in vitro. With SoxS being closely related to MarA, we analyzed the effects of the SoxS mutations in the context of the MarA-mar crystal structure and with respect to the NMR study of MarA-DNA complexes in solution. From the properties of the alanine substitutions, we conclude the following. (1) Surface-exposed residues of helix 3 and helix 6, the recognition helices of the dual HTH motifs, are important to DNA binding and transcription activation; however, substitutions of residues predicted from the MarA-mar crystal structure to make contact with the sugar-phosphate backbone are more detrimental to DNA binding than mutations predicted to make base-specific contacts. (2) Substitution of several residues within the recognition helix predicted to make base-specific contacts with RE2 have relatively little effect on DNA-binding, suggesting the possibility of alternative protein-DNA interactions than those inferred from the MarA-mar crystal structure. (3) DNA binding and transcription activation were reduced by substitution of conserved amino acid residues comprising the hydrophobic core, presumably because they disrupt the structural integrity of SoxS. (4) Mutant K30A appears to be a positive control mutant defective in a protein-protein interaction with RNA polymerase that is required for transcription activation at all SoxS-dependent promoters because it binds and bends DNA normally but fails to activate transcription from both classes of promoters. Alanine substitutions of surface-exposed residues H3, K5, D9, S31, and V45 confer a similar phenotype. Since these residues are near K30 on the surface of the protein, the surface formed by the six residues may be used to make protein-protein interactions with RNA polymerase that are required for transcription activation at both class I and class II SoxS-dependent promoters. (5) Mutants F74A, D75A, M78A, D79A and Q85A appear to define a surface required for protein-protein interaction with RNA polymerase specifically at class II promoters because these positive control mutants bind and bend DNA normally but are defective in activation of class II promoters but not class I promoters. These SoxS mutants that bind and bend DNA normally but are defective in transcription activation represent the first positive control mutants with putative defects in protein-protein interactions with RNA polymerase among the SoxS/MarA/Rob subset of the AraC/XylS family of transcription regulators.</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/12217688?dopt=Abstract</style></custom1></record></records></xml>