Microbiology

Alexander R. Horswill, PhD

Portrait

Associate Professor of Microbiology

Contact Information

Office: 540F Eckstein Medical Research Building
431 Newton Rd
Iowa City, IA 52242
Office Phone: 319-335-7783

Lab: 540 Eckstein Medical Research Building
431 Newton Rd
Iowa City, IA 52242
Phone: 319-335-7996

Email: alex-horswill@uiowa.edu
Web: Horswill Lab Website

Education

BS, Bacteriology, University of Wisconsin - Madison
PhD, Bacteriology, University of Wisconsin - Madison

Post Doctoral, Chemistry, Pennsylvania State University

Education/Training Program Affiliations

Biosciences Graduate Program
Department of Microbiology Graduate Program
Medical Scientist Training Program

Research Summary

Many critical processes in bacteria are regulated by cell density. By producing chemical signals, bacteria can communicate and coordinate regulatory events in large populations. These signals accumulate to a critical threshold and elicit a regulatory response at the appropriate cell density. This phenomenon of density-dependent regulation is frequently termed quorum sensing or autoinduction, and the signals controlling this process are acyl-homoserine lactones (HSLs) in Gram negative bacteria and peptides in Gram positive bacteria. While HSLs have been investigated extensively, studies on peptide regulation have lagged behind, even though many Gram positive bacteria regulate pathogenesis using these signals.

My research focuses on the peptide quorum sensing system of Staphylococcus aureus. The agr locus of this bacterium produces an extracellular peptide signal, called an autoinducing peptide (AIP). At the correct cell population, this signal controls expression of the virulence response, including down-regulating the expression of surface proteins, such as adhesins and antigens, and up-regulating the expression of virulence factors, such as hemolysins, proteases, and toxins. Structural studies have determined that the S. aureus AIP is an eight-residue peptide, with the five C-terminal residues cyclized into a thiolactone ring. However, there is little information available about the proteins involved in the maturation and export process, and the details of the biosynthetic mechanism remain unclear. My laboratory will take genetic, molecular, and biochemical approaches towards defining the route of AIP biosynthesis and the mode of action of these signals. With a better understanding of the AIP system, it will be possible to develop AIP inhibitors that could block S. aureus virulence. We will explore cutting-edge peptide technologies to discover such inhibitors and investigate their implementation in S. aureus.

Recent efforts have suggested that S. aureus quorum sensing and biofilm formation are interconnected. The ability of S. aureus to develop biofilms on medical implants is an important determinant in infections, high-lighting the need for more studies in this area. As we learn more about AIP biosynthesis and regulation, this research will be extended toward studies on biofilms, with a goal of improving our understanding of this connection.

Center, Program and Institute Affiliations

Center for Biocatalysis and Bioprocessing
Center for Immunology and Immune-based Diseases
Inflammation Program

All Publications

Olson M, Todd D, Schaeffer C, Paharik A, Van Dyke M, Büttner H, Dunman P, Rohde H, Cech N, Fey P, Horswill A.  Staphylococcus epidermidis agr Quorum-Sensing System: Signal Identification, Cross Talk, and Importance in Colonization.  J Bacteriol.  2014 October 1. 196(19):3482-93.
[Link]

Figueroa M, Jarmusch A, Raja H, El-Elimat T, Kavanaugh J, Horswill A, Cooks R, Cech N, Oberlies N.  Polyhydroxyanthraquinones as quorum sensing inhibitors from the guttates of Penicillium restrictum and their analysis by desorption electrospray ionization mass spectrometry.  J Nat Prod.  2014 June 27. 77(6):1351-8.
[Link]

Sully E, Malachowa N, Elmore B, Alexander S, Femling J, Gray B, DeLeo F, Otto M, Cheung A, Edwards B, Sklar L, Horswill A, Hall P, Gresham H.  Selective Chemical Inhibition of agr Quorum Sensing in Staphylococcus aureus Promotes Host Defense with Minimal Impact on Resistance.  PLoS Pathog.  2014 June 12. 10(6):e1004174.
[Link]

Flack C, Zurek O, Meishery D, Pallister K, Malone C, Horswill A, Voyich J.  Differential regulation of staphylococcal virulence by the sensor kinase SaeS in response to neutrophil-derived stimuli.  Proc Natl Acad Sci USA.  2014 May 13. 111(19):E2037-45.
[Link]

Sommerfield Ross S, Tu M, Falsetta M, Ketterer M, Kiedrowski M, Horswill A, Apicella M, Reinhardt J, Fiegel J.  Quantification of confocal images of biofilms grown on irregular surfaces.  J Microbiol Methods.  2014 May. 100:111-20.
[Link]

Kiedrowski M, Crosby H, Hernandez F, Malone C, McNamara J, Horswill A.  Staphylococcus aureus Nuc2 Is a Functional, Surface-Attached Extracellular Nuclease.  PLoS One.  2014 April 21. 9(4):e95574.
[Link]

White M, Boyd J, Horswill A, Nauseef W.  Phosphatidylinositol-specific phospholipase C contributes to survival of Staphylococcus aureus USA300 in human blood and neutrophils.  Infect Immun.  2014 April. 82(4):1559-71.
[Link]

Hernandez F, Huang L, Olson M, Powers K, Hernandez L, Meyerholz D, Thedens D, Behlke M, Horswill A, McNamara J.  Noninvasive imaging of Staphylococcus aureus infections with a nuclease-activated probe.  Nat Med.  2014 March. 20(3):301-6.
[Link]

Olson M, Horswill A.  Bacteriophage Transduction in Staphylococcus epidermidis.  Methods Mol Biol.  2014. 1106:167-72.
[Link]

Pang Y, Schwartz J, Bloomberg S, Boyd J, Horswill A, Nauseef W.  Methionine sulfoxide reductases protect against oxidative stress in Staphylococcus aureus encountering exogenous oxidants and human neutrophils.  J Innate Immun.  2014. 6(3):353-64.
[Link]

Ibberson C, Jones C, Singh S, Wise M, Hart M, Zurawski D, Horswill A.  Staphylococcus aureus hyaluronidase is a CodY-regulated virulence factor.  Infect Immun.  2014. Epub ahead of print.
[Link]

DeLeon S, Clinton A, Fowler H, Everett J, Horswill A, Rumbaugh K.  Synergistic Interactions of Pseudomonas aeruginosa and Staphylococcus aureus in an In Vitro Wound Model.  Infect Immun.  2014. Epub ahead of print.
[Link]

Zurek O, Nygaard T, Watkins R, Pallister K, Torres V, Horswill A, Voyich J.  The role of innate immunity in promoting SaeR/S-mediated virulence in Staphylococcus aureus.  J Innate Immun.  2014. 6(1):21-30.
[Link]

Cech N, Horswill A.  Small-molecule quorum quenchers to prevent Staphylococcus aureus infection.  Future Microbiol.  2013 December. 8:1511-4.
[Link]

Snowden J, Beaver M, Beenken K, Smeltzer M, Horswill A, Kielian T.  Staphylococcus aureus sarA regulates inflammation and colonization during central nervous system biofilm formation.  PLoS One.  2013 December. 8(12):e84089.
[Link]

Walker J, Crosby H, Spaulding A, Salgado-Pabón W, Malone C, Rosenthal C, Schlievert P, Boyd J, Horswill A.  The Staphylococcus aureus ArlRS two-component system is a novel regulator of agglutination and pathogenesis.  PLoS Pathog.  2013 December. 9(12):e1003819.
[Link]

Yu J, Madsen M, Carruthers M, Phillips G, Kavanaugh J, Boyd J, Horswill A, Minion F.  Analysis of autoinducer-2 quorum sensing in Yersinia pestis.  Infect Immun.  2013 November. 81(11):4053-62.
[Link]

Chiu I, Heesters B, Ghasemlou N, Von Hehn C, Zhao F, Tran J, Wainger B, Strominger A, Muralidharan S, Horswill A, Bubeck Wardenburg J, Hwang S, Carroll M, Woolf C.  Bacteria activate sensory neurons that modulate pain and inflammation.  Nature.  2013 September 5. 501(7465):52-7.
[Link]

Mootz J, Malone C, Shaw L, Horswill A.  Staphopains modulate Staphylococcus aureus biofilm integrity.  Infect Immun.  2013 September. 81(9):3227-38.
[Link]

Salgado-Pabón W, Breshears L, Spaulding A, Merriman J, Stach C, Horswill A, Peterson M, Schlievert P.  Superantigens are critical for Staphylococcus aureus Infective endocarditis, sepsis, and acute kidney injury.  MBio.  2013 August 20. 4(4):pii: e00494-13.
[Link]

Spaulding A, Salgado-Pabón W, Kohler P, Horswill A, Leung D, Schlievert P.  Staphylococcal and streptococcal superantigen exotoxins.  Clin Microbiol Rev.  2013 July. 26(3):422-47.
[Link]

Junio H, Todd D, Ettefagh K, Ehrmann B, Kavanaugh J, Horswill A, Cech N.  Quantitative analysis of autoinducing peptide I (AIP-I) from Staphylococcus aureus cultures using ultrahigh performance liquid chromatography-high resolving power mass spectrometry.  J Chromatogr B Analyt Technol Biomed Life Sci.  2013 July 1. 930:7-12.
[Link]

Olson M, Horswill A.  Staphylococcus aureus Osteomyelitis: Bad to the Bone.  Cell Host Microbe.  2013 June 12. 13(6):629-31.
[Link]

Moormeier D, Endres J, Mann E, Sadykov M, Horswill A, Rice K, Fey P, Bayles K.  Use of microfluidic technology to analyze gene expression during Staphylococcus aureus biofilm formation reveals distinct physiological niches.  Appl Environ Microbiol.  2013 June. 79(11):3413-24.
[Link]

LaRock C, Yu J, Horswill A, Parsek M, Minion F.  Transcriptome Analysis of Acyl-Homoserine Lactone-Based Quorum Sensing Regulation in Yersinia pestis.  PLoS One.  2013 April 19. 8(4):e62337.
[Link]

Olson M, King J, Yahr T, Horswill A.  Sialic acid catabolism in Staphylococcus aureus.  J Bacteriol.  2013 April. 195(8):1779-88.
[Link]

Olson M, Nygaard T, Ackermann L, Watkins R, Zurek O, Pallister K, Griffith S, Kiedrowski M, Flack C, Kavanaugh J, Kreiswirth B, Horswill A, Voyich J.  Staphylococcus aureus nuclease is a SaeR/S-dependent virulence factor.  Infect Immun.  2013 April. 81(4):1316-24.
[Link]

Abdelhady W, Bayer A, Seidl K, Nast C, Kiedrowski M, Horswill A, Yeaman M, Xiong Y.  Reduced vancomycin susceptibility in an in vitro catheter-related biofilm model correlates with poor therapeutic outcomes in experimental endocarditis due to methicillin-resistant Staphylococcus aureus.  Antimicrob Agents Chemother.  2013 March. 57(3):1447-54.
[Link]

Kolar S, Antonio Ibarra J, Rivera F, Mootz J, Davenport J, Stevens S, Horswill A, Shaw L.  Extracellular proteases are key mediators of Staphylococcus aureus virulence via the global modulation of virulence-determinant stability.  Microbiologyopen.  2013 February. 2(1):18-34.
[Link]

Hall P, Elmore B, Spang C, Alexander S, Manifold-Wheeler B, Castleman M, Daly S, Peterson M, Sully E, Femling J, Otto M, Horswill A, Timmins G, Gresham H.  Nox2 modification of LDL is essential for optimal apolipoprotein B-mediated control of agr type III Staphylococcus aureus quorum-sensing.  PLoS Pathog.  2013 February. 9(2):e1003166.
[Link]

Thoendel M, Horswill A.  Random mutagenesis and topology analysis of the autoinducing peptide biosynthesis proteins in Staphylococcus aureus.  Mol Microbiol.  2013 January. 87(2):318-37.
[Link]

Arnison P, Bibb M, Bierbaum G, Bowers A, Bugni T, Bulaj G, Camarero J, Campopiano D, Challis G, Clardy J, Cotter P, Craik D, Dawson M, Dittmann E, Donadio S, Dorrestein P, Entian K, Fischbach M, Garavelli J, Göransson U, Gruber C, Haft D, Hemscheidt T, Hertweck C, Hill C, Horswill A, Jaspars M, Kelly W, Klinman J, Kuipers O, Link A, Liu W, Marahiel M, Mitchell D, Moll G, Moore B, Müller R, Nair S, Nes I, Norris G, Olivera B, Onaka H, Patchett M, Piel J, Reaney M, Rebuffat S, Ross R, Sahl H, Schmidt E, Selsted M, Severinov K, Shen B, Sivonen K, Smith L, Stein T, Süssmuth R, Tagg J, Tang G, Truman A, Vederas J, Walsh C, Walton J, Wenzel S, Wiley J, van der Donk W.  Ribosomally synthesized and post-translationally modified peptide natural products: overview and recommendations for a universal nomenclature.  Nat Prod Rep.  2013 January. 30(1):108-60.
[Link]

Zielinska A, Beenken K, Mrak L, Spencer H, Post G, Skinner R, Tackett A, Horswill A, Smeltzer M.  sarA-mediated repression of protease production plays a key role in the pathogenesis of Staphylococcus aureus USA300 isolates.  Mol Microbiol.  2012 December. 86(5):1183-96.
[Link]

Cech N, Junio H, Ackermann L, Kavanaugh J, Horswill A.  Quorum quenching and antimicrobial activity of goldenseal (Hydrastis canadensis) against methicillin-resistant Staphylococcus aureus (MRSA).  Planta Med.  2012 September. 78(14):1556-61.
[Link]

Laarman A, Mijnheer G, Mootz J, van Rooijen W, Ruyken M, Malone C, Heezius E, Ward R, Milligan G, van Strijp J, de Haas C, Horswill A, van Kessel K, Rooijakkers S.  Staphylococcus aureus Staphopain A inhibits CXCR2-dependent neutrophil activation and chemotaxis.  EMBO J.  2012 August 29. 31(17):3607-19.
[Link]

Boles B, Horswill A.  Swimming cells promote a dynamic environment within biofilms.  Proc Natl Acad Sci U S A.  2012 August 7. 109(32):12848-9.
[Link]

Kaplan J, Izano E, Gopal P, Karwacki M, Kim S, Bose J, Bayles K, Horswill A.  Low levels of β-lactam antibiotics induce extracellular DNA release and biofilm formation in Staphylococcus aureus.  MBio.  2012 July 31. 3(4):e00198-12.
[Link]

Pezzulo A, Tang X, Hoegger M, Alaiwa M, Ramachandran S, Moninger T, Karp P, Wohlford-Lenane C, Haagsman H, van Eijk M, Bánfi B, Horswill A, Stoltz D, McCray P, Welsh M, Zabner J.  Reduced airway surface pH impairs bacterial killing in the porcine cystic fibrosis lung.  Nature.  2012 July 4. 487(7405):109-13.
[Link]

Gonzalez D, Okumura C, Hollands A, Kersten R, Akong-Moore K, Pence M, Malone C, Derieux J, Moore B, Horswill A, Dixon J, Dorrestein P, Nizet V.  Novel phenol-soluble modulin derivatives in community-associated methicillin-resistant Staphylococcus aureus identified through imaging mass spectrometry.  J Biol Chem.  2012 April 20. 287(17):13889-98.
[Link]

Hernandez F, Stockdale K, Huang L, Horswill A, Behlke M, McNamara J.  Degradation of nuclease-stabilized RNA oligonucleotides in Mycoplasma-contaminated cell culture media.  Nucleic Acid Ther.  2012 February. 22(1):58-68.
[Link]

Walker J, Horswill A.  A coverslip-based technique for evaluating Staphylococcus aureus biofilm formation on human plasma.  Front Cell Infect Microbiol.  2012. 2:39.
[Link]

Nygaard T, Pallister K, DuMont A, DeWald M, Watkins R, Pallister E, Malone C, Griffith S, Horswill A, Torres V, Voyich J.  Alpha-toxin induces programmed cell death of human T cells, B cells, and monocytes during USA300 infection.  PLoS One.  2012. 7(5):e36532.
[Link]

Kiedrowski M, Horswill A.  New approaches for treating staphylococcal biofilm infections.  Ann N Y Acad Sci.  2011 December. 1241:104-21.
[Link]

Kavanaugh J, Gakhar L, Horswill A.  The structure of LsrB from Yersinia pestis complexed with autoinducer-2.  Acta Crystallogr Sect F Struct Biol Cryst Commun.  2011 December. 67(Pt 12):1501-5.
[Link]

Wörmann M, Reichmann N, Malone C, Horswill A, Gründling A.  Proteolytic cleavage inactivates the Staphylococcus aureus lipoteichoic acid synthase.  J Bacteriol.  2011 October. 193(19):5279-91.
[Link]

Boles B, Horswill A.  Staphylococcal biofilm disassembly.  Trends Microbiol.  2011 September. 19(9):449-55.
[Link]

Lin Y, Anderson M, Kohler P, Strandberg K, Olson M, Horswill A, Schlievert P, Peterson M.  Proinflammatory exoprotein characterization of toxic shock syndrome Staphylococcus aureus.  Biochemistry.  2011 August 23. 50(33):7157-67.
[Link]

Benson M, Lilo S, Wasserman G, Thoendel M, Smith A, Horswill A, Fraser J, Novick R, Shopsin B, Torres V.  Staphylococcus aureus regulates the expression and production of the staphylococcal superantigen-like secreted proteins in a Rot-dependent manner.  Mol Microbiol.  2011 August. 81(3):659-75.
[Link]

Thurlow L, Hanke M, Fritz T, Angle A, Aldrich A, Williams S, Engebretsen I, Bayles K, Horswill A, Kielian T.  Staphylococcus aureus biofilms prevent macrophage phagocytosis and attenuate inflammation in vivo.  J Immunol.  2011 June 1. 186(11):6585-96.
[Link]

Laarman A, Ruyken M, Malone C, van Strijp J, Horswill A, Rooijakkers S.  Staphylococcus aureus metalloprotease aureolysin cleaves complement C3 to mediate immune evasion.  J Immunol.  2011 June 1. 186(11):6445-53.
[Link]

Kirchdoerfer R, Garner A, Flack C, Mee J, Horswill A, Janda K, Kaufmann G, Wilson I.  Structural basis for ligand recognition and discrimination of a quorum-quenching antibody.  J Biol Chem.  2011 May 13. 286(19):17351-8.
[Link]

Hammond A, Miller K, Kruczek C, Dertien J, Colmer-Hamood J, Griswold J, Horswill A, Hamood A.  An in vitro biofilm model to examine the effect of antibiotic ointments on biofilms produced by burn wound bacterial isolates.  Burns.  2011 March. 37(2):312-21.
[Link]

Thoendel M, Kavanaugh J, Flack C, Horswill A.  Peptide signaling in the staphylococci.  Chem Rev.  2011 January 12. 111(1):117-51.
[Link]

Kiedrowski M, Kavanaugh J, Malone C, Mootz J, Voyich J, Smeltzer M, Bayles K, Horswill A.  Nuclease modulates biofilm formation in community-associated methicillin-resistant Staphylococcus aureus.  PLoS One.  2011. 6(11):e26714.
[Link]

Olson M, Horswill A.  Sialic acid utilization in Staphylococcus aureus.  Gordon Conference on Staphylococcal Diseases, Lucca, Italy.  2011. 

Beenken K, Mrak L, Griffin L, Zielinska A, Shaw L, Rice K, Horswill A, Bayles K, Smeltzer M.  Epistatic relationships between sarA and agr in Staphylococcus aureus biofilm formation.  PLoS One.  2010 May 24. 5(5):e10790.
[Link]

Stoltz D, Meyerholz D, Pezzulo A, Ramachandran S, Rogan M, Davis G, Hanfland R, Wohlford-Lenane C, Dohrn C, Bartlett J, Nelson G, Chang E, Taft P, Ludwig P, Estin M, Hornick E, Launspach J, Samuel M, Rokhlina T, Harp P, Ostedgaard L, Uc A, Starner T, Horswill A, Brogden K, Prather R, Richter S, Shilyansky J, McCray P, Zabner J, Welsh M.  Cystic fibrosis pigs develop lung disease and exhibit defective bacterial eradication at birth.  Sci Transl Med.  2010 April 28. 2(29):29ra31.
[Link]

Boles B, Thoendel M, Roth A, Horswill A.  Identification of genes involved in polysaccharide-independent Staphylococcus aureus biofilm formation.  PLoS One.  2010 April 14. 5(4):e10146.
[Link]

Pang Y, Schwartz J, Thoendel M, Ackermann L, Horswill A, Nauseef W.  agr-Dependent interactions of Staphylococcus aureus USA300 with human polymorphonuclear neutrophils.  J Innate Immun.  2010. 2(6):546-59.
[Link]

Thoendel M, Horswill A.  Biosynthesis of peptide signals in gram-positive bacteria.  Adv Appl Microbiol.  2010. 71:91-112.
[Link]

Mootz J, Malone C, Horswill A.  Extracellular proteases contribute to the Staphylococcus aureus Sigma Factor B biofilm negative phenotype.  International Gram-Positive Pathogen Meeting, Omaha, NE.  2010. 

Thoendel M, Horswill A.  New Insights into AgrB Structure and Function in Staphylococcus aureus.  International Gram-Positive Pathogen Meeting, Omaha, NE.  2010. 

Thoendel M, Horswill A.  New Insights into AgrB Structure and Function in Staphylococcus aureus.  International Symposium on Staphylococci and Staphylococcal Infections, Bath England.  2010. 

Berends E, Horswill A, Haste N, Monestier M, Nizet V, von Köckritz-Blickwede M.  Nuclease expression by Staphylococcus aureus facilitates escape from neutrophil extracellular traps.  J Innate Immun.  2010. 2(6):576-86.
[Link]

Kiedrowski M, Kavanaugh J, Malone C, Voyich J, Smeltzer M, Bayles K, Horswill A.  Nuclease modulates biofilm formation in community-associated methicillin-resistant Staphylococcus aureus.  International Gram-Positive Pathogen Meeting, Omaha, NE.  2010. 

Olson M, Horswill A.  Sialic acid utilization in Staphylococcus aureus.  International Gram-Positive Pathogen Meeting, Omaha, NE.  2010. 

Lauderdale K, Malone C, Boles B, Morcuende J, Horswill A.  Biofilm dispersal of community-associated methicillin-resistant Staphylococcus aureus on orthopedic implant material.  J Orthop Res.  2010 January. 28(1):55-61.
[Link]

Thoendel M, Horswill A.  Identification of Staphylococcus aureus AgrD residues required for autoinducing peptide biosynthesis.  J Biol Chem.  2009 August 14. 284(33):21828-38.
[Link]

Mann E, Rice K, Boles B, Endres J, Ranjit D, Chandramohan L, Tsang L, Smeltzer M, Horswill A, Bayles K.  Modulation of eDNA release and degradation affects Staphylococcus aureus biofilm maturation.  PLoS One.  2009 June 9. 4(6):e5822.
[Link]

Malone C, Boles B, Lauderdale K, Thoendel M, Kavanaugh J, Horswill A.  Fluorescent reporters for Staphylococcus aureus.  J Microbiol Methods.  2009 June. 77(3):251-60.
[Link]

Lauderdale K, Boles B, Cheung A, Horswill A.  Interconnections between Sigma B, agr, and proteolytic activity in Staphylococcus aureus biofilm maturation.  Infect Immun.  2009 April. 77(4):1623-35.
[Link]

Thoendel M, Horswill A.  Molecular characterization of the Staphylococcus aureus quorum-sensing propeptide.  2009. 

Thoendel M, Horswill A.  Molecular characterization of the Staphylococcus aureus quorum-sensing propeptide.  24th Annual MD/PhD Student Conference, Keystone, CO.  2009. 

Boles B, Thoendel M, Horswill A.  Staphylococcus aureus factors important for biofilm formation.  Gordon Conference on Staphylococcal Diseases, Waterville Valley, NH.  2009. 

Horswill A, Nauseef W.  Host interception of bacterial communication signals.  Cell Host Microbe.  2008 December 11. 4(6):507-9.
[Link]

Boles B, Horswill A.  Agr-mediated dispersal of Staphylococcus aureus biofilms.  PLoS Pathog.  2008 April. 4(4):e1000052.
[Link]

Thoendel M, Horswill A.  New insights on autoinducing peptide biosynthesis in Staphylococcus aureus.  International Gram-Positive Pathogen Meeting, Omaha, NE.  2008. 

Boles B, Horswill A.  The cyclization of peptides and proteins with inteins.  John Wiley & Sons.  2008. 

Kiedrowski M, Boles B, Horswill A.  The effect of nuclease activity on Staphylococcus aureus biofilms.  International Gram-Positive Bacterial Pathogen Meeting, Omaha, NE.  2008. 

Malone C, Boles B, Horswill A.  Biosynthesis of Staphylococcus aureus autoinducing peptides by using the synechocystis DnaB mini-intein.  Appl Environ Microbiol.  2007 October. 73(19):6036-44.
[Link]

Kavanaugh J, Thoendel M, Horswill A.  A role for type I signal peptidase in Staphylococcus aureus quorum sensing.  Mol Microbiol.  2007 August. 65(3):780-98.
[Link]

Cheng L, Naumann T, Horswill A, Hong S, Venters B, Tomsho J, Benkovic S, Keiler K.  Discovery of antibacterial cyclic peptides that inhibit the ClpXP protease.  Protein Sci.  2007 August. 16(8):1535-42.
[Link]

Kavanaugh J, Thoendel M, Horswill A.  A role for type 1 signal peptidase in Staphylococcus aureus quorum-sensing.  General Meeting of the American Society for Microbiology, Toronto, CA.  2007. 

Horswill A, Stoodley P, Stewart P, Parsek M.  The effect of the chemical, biological, and physical environment on quorum sensing in structured microbial communities.  Anal Bioanal Chem.  2007 January. 387(2):371-80.
[Link]

Horswill A, Benkovic S.  Identifying small-molecule modulators of protein-protein interactions.  Curr Protoc Protein Sci.  2006 December. Chapter 19:Unit 19.15.
[Link]

Horswill A, Benkovic S.  Cyclic peptides, a chemical genetics tool for biologists.  Cell Cycle.  2005 April. 4(4):552-5.
[Link]

Horswill A, Savinov S, Benkovic S.  A systematic method for identifying small-molecule modulators of protein-protein interactions.  Proc Natl Acad Sci U S A.  2004 November 2. 101(44):15591-6.
[Link]

Saraf M, Horswill A, Benkovic S, Maranas C.  FamClash: a method for ranking the activity of engineered enzymes.  Proc Natl Acad Sci U S A.  2004 March 23. 101(12):4142-7.
[Link]

Lewis J, Horswill A, Schwem B, Escalante-Semerena J.  The Tricarballylate utilization (tcuRABC) genes of Salmonella enterica serovar Typhimurium LT2.  J Bacteriol.  2004 March. 186(6):1629-37.
[Link]

Horswill A, Naumann T, Benkovic S.  Using incremental truncation to create libraries of hybrid enzymes.  Methods Enzymol.  2004. 388:50-60.
[Link]

Gulick A, Starai V, Horswill A, Homick K, Escalante-Semerena J.  The 1.75 A crystal structure of acetyl-CoA synthetase bound to adenosine-5'-propylphosphate and coenzyme A.  Biochemistry.  2003 March 18. 42(10):2866-73.
[Link]

Fonseca M, Buan N, Horswill A, Rayment I, Escalante-Semerena J.  The ATP:Co(I)rrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica requires the 2'-OH group of ATP for function and yields inorganic triphosphate as its reaction byproduct.  J Biol Chem.  2002 September 6. 277(36):33127-31.
[Link]

Horswill A, Escalante-Semerena J.  Characterization of the propionyl-CoA synthetase (PrpE) enzyme of Salmonella enterica: residue Lys592 is required for propionyl-AMP synthesis.  Biochemistry.  2002 February 19. 41(7):2379-87.
[Link]

Gulick A, Horswill A, Thoden J, Escalante-Semerena J, Rayment I.  Pentaerythritol propoxylate: a new crystallization agent and cryoprotectant induces crystal growth of 2-methylcitrate dehydratase.  Acta Crystallogr D Biol Crystallogr.  2002 February. 58(Pt 2):306-9.
[Link]

Horswill A, Dudding A, Escalante-Semerena J.  Studies of propionate toxicity in Salmonella enterica identify 2-methylcitrate as a potent inhibitor of cell growth.  J Biol Chem.  2001 June 1. 276(22):19094-101.
[Link]

Ciche T, Bintrim S, Horswill A, Ensign J.  A Phosphopantetheinyl transferase homolog is essential for Photorhabdus luminescens to support growth and reproduction of the entomopathogenic nematode Heterorhabditis bacteriophora.  J Bacteriol.  2001 May. 183(10):3117-26.
[Link]

Horswill A, Escalante-Semerena J.  In vitro conversion of propionate to pyruvate by Salmonella enterica enzymes: 2-methylcitrate dehydratase (PrpD) and aconitase Enzymes catalyze the conversion of 2-methylcitrate to 2-methylisocitrate.  Biochemistry.  2001 April 17. 40(15):4703-13.
[Link]

Horswill A, Escalante-Semerena J.  Salmonella typhimurium LT2 catabolizes propionate via the 2-methylcitric acid cycle.  J Bacteriol.  1999 September. 181(18):5615-23.
[Link]

Horswill A, Escalante-Semerena J.  The prpE gene of Salmonella typhimurium LT2 encodes propionyl-CoA synthetase.  Microbiology.  1999 June. 145(Pt 6):1381-8.
[Link]

Tsang A, Horswill A, Escalante-Semerena J.  Studies of regulation of expression of the propionate (prpBCDE) operon provide insights into how Salmonella typhimurium LT2 integrates its 1,2-propanediol and propionate catabolic pathways.  J Bacteriol.  1998 December. 180(24):6511-8.
[Link]

Horswill A, Escalante-Semerena J.  Propionate catabolism in Salmonella typhimurium LT2: two divergently transcribed units comprise the prp locus at 8.5 centisomes, prpR encodes a member of the sigma-54 family of activators, and the prpBCDE genes constitute an operon.  J Bacteriol.  1997 February. 179(3):928-40.
[Link]

Rondon M, Horswill A, Escalante-Semerena J.  DNA polymerase I function is required for the utilization of ethanolamine, 1,2-propanediol, and propionate by Salmonella typhimurium LT2.  J Bacteriol.  1995 December. 177(24):7119-24.
[Link]

Date Last Modified: 06/07/2014 - 21:56:23