1
|
Lapointe G, Skepper CK, Holder LM, Armstrong D, Bellamacina C, Blais J, Bussiere D, Bian J, Cepura C, Chan H, Dean CR, De Pascale G, Dhumale B, Fisher LM, Fulsunder M, Kantariya B, Kim J, King S, Kossy L, Kulkarni U, Lakshman J, Leeds JA, Ling X, Lvov A, Ma S, Malekar S, McKenney D, Mergo W, Metzger L, Mhaske K, Moser HE, Mostafavi M, Namballa S, Noeske J, Osborne C, Patel A, Patel D, Patel T, Piechon P, Polyakov V, Prajapati K, Prosen KR, Reck F, Richie DL, Sanderson MR, Satasia S, Savani B, Selvarajah J, Sethuraman V, Shu W, Tashiro K, Thompson KV, Vaarla K, Vala L, Veselkov DA, Vo J, Vora B, Wagner T, Wedel L, Williams SL, Yendluri S, Yue Q, Yifru A, Zhang Y, Rivkin A. Discovery and Optimization of DNA Gyrase and Topoisomerase IV Inhibitors with Potent Activity against Fluoroquinolone-Resistant Gram-Positive Bacteria. J Med Chem 2021; 64:6329-6357. [PMID: 33929852 DOI: 10.1021/acs.jmedchem.1c00375] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Herein, we describe the discovery and optimization of a novel series that inhibits bacterial DNA gyrase and topoisomerase IV via binding to, and stabilization of, DNA cleavage complexes. Optimization of this series led to the identification of compound 25, which has potent activity against Gram-positive bacteria, a favorable in vitro safety profile, and excellent in vivo pharmacokinetic properties. Compound 25 was found to be efficacious against fluoroquinolone-sensitive Staphylococcus aureus infection in a mouse thigh model at lower doses than moxifloxacin. An X-ray crystal structure of the ternary complex formed by topoisomerase IV from Klebsiella pneumoniae, compound 25, and cleaved DNA indicates that this compound does not engage in a water-metal ion bridge interaction and forms no direct contacts with residues in the quinolone resistance determining region (QRDR). This suggests a structural basis for the reduced impact of QRDR mutations on antibacterial activity of 25 compared to fluoroquinolones.
Collapse
Affiliation(s)
- Guillaume Lapointe
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Colin K Skepper
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Lauren M Holder
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Duncan Armstrong
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Cornelia Bellamacina
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Johanne Blais
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Dirksen Bussiere
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Jianwei Bian
- Novartis Global Drug Development, Pudong, Shanghai 201203, China
| | - Cody Cepura
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Helen Chan
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Charles R Dean
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Gianfranco De Pascale
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Bhavesh Dhumale
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - L Mark Fisher
- Molecular and Clinical Sciences Research Institute, St George's, University of London, London SW17 0RE, U.K
| | - Mangesh Fulsunder
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Bhavin Kantariya
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Julie Kim
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Sean King
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Lauren Kossy
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Upendra Kulkarni
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Jay Lakshman
- Novartis Global Drug Development, East Hanover, New Jersey 07936, United States
| | - Jennifer A Leeds
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Xiaolan Ling
- Novartis Global Drug Development, Pudong, Shanghai 201203, China
| | - Anatoli Lvov
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Sylvia Ma
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Swapnil Malekar
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - David McKenney
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Wosenu Mergo
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Louis Metzger
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Keshav Mhaske
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Heinz E Moser
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Mina Mostafavi
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Sunil Namballa
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Jonas Noeske
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Colin Osborne
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Ashish Patel
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Darshit Patel
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Tushar Patel
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Philippe Piechon
- Novartis Institutes for BioMedical Research, Basel 4002, Switzerland
| | - Valery Polyakov
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Krunal Prajapati
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Katherine R Prosen
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Folkert Reck
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Daryl L Richie
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Mark R Sanderson
- Randall Centre for Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, U.K
| | - Shailesh Satasia
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Bhautik Savani
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Jogitha Selvarajah
- Molecular and Clinical Sciences Research Institute, St George's, University of London, London SW17 0RE, U.K
| | - Vijay Sethuraman
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Wei Shu
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Kyuto Tashiro
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Katherine V Thompson
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Krishniah Vaarla
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Lakhan Vala
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Dennis A Veselkov
- Randall Centre for Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, U.K
| | - Jason Vo
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Bhavesh Vora
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Trixie Wagner
- Novartis Institutes for BioMedical Research, Basel 4002, Switzerland
| | - Laura Wedel
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Sarah L Williams
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Satya Yendluri
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Qin Yue
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Aregahegn Yifru
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Yong Zhang
- Novartis Global Drug Development, Pudong, Shanghai 201203, China
| | - Alexey Rivkin
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| |
Collapse
|
2
|
Wang J, Ye X, Yang X, Cai Y, Wang S, Tang J, Sachdeva M, Qian Y, Hu W, Leeds JA, Yuan Y. Discovery of Novel Antibiotics as Covalent Inhibitors of Fatty Acid Synthesis. ACS Chem Biol 2020; 15:1826-1834. [PMID: 32568510 DOI: 10.1021/acschembio.9b00982] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The steady increase in the prevalence of multidrug-resistant Staphylococcus aureus has made the search for novel antibiotics to combat this clinically important pathogen an urgent matter. In an effort to discover antibacterials with new chemical structures and mechanisms, we performed a growth inhibition screen of a synthetic library against S. aureus and discovered a promising scaffold with a 1,3,5-oxadiazin-2-one core. These compounds are potent against both methicillin-sensitive and methicillin-resistant S. aureus strains. Isolation of compound-resistant strains followed by whole genome sequencing revealed its cellular target as FabH, a key enzyme in bacterial fatty acid synthesis. Detailed mechanism of action studies suggested the compounds inhibit FabH activity by covalently modifying its active site cysteine residue with high selectivity. A crystal structure of FabH protein modified by a selected compound Oxa1 further confirmed covalency and suggested a possible mechanism for reaction. Moreover, the structural snapshot provided an explanation for compound selectivity. On the basis of the structure, we designed and synthesized Oxa1 derivatives and evaluated their antibacterial activity. The structure-activity relationship supports the hypothesis that noncovalent recognition between compounds and FabH is critical for the activity of these covalent inhibitors. We believe further optimization of the current scaffold could lead to an antibacterial with potential to treat drug-resistant bacteria in the clinic.
Collapse
Affiliation(s)
- Jia Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xiaoping Ye
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xiaohan Yang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Youyan Cai
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Shengjun Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jieyu Tang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Meena Sachdeva
- Novartis Institutes for Biomedical Research, Inc., Infectious Diseases Area, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Yu Qian
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Wenhao Hu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jennifer A. Leeds
- Novartis Institutes for Biomedical Research, Inc., Infectious Diseases Area, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Yanqiu Yuan
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Guangdong Provincial Key Laboratory of Drug Non-Clinical Evaluation and Research, Guangzhou 510990, China
| |
Collapse
|
3
|
Skepper CK, Armstrong D, Balibar CJ, Bauer D, Bellamacina C, Benton BM, Bussiere D, De Pascale G, De Vicente J, Dean CR, Dhumale B, Fisher LM, Fuller J, Fulsunder M, Holder LM, Hu C, Kantariya B, Lapointe G, Leeds JA, Li X, Lu P, Lvov A, Ma S, Madhavan S, Malekar S, McKenney D, Mergo W, Metzger L, Moser HE, Mutnick D, Noeske J, Osborne C, Patel A, Patel D, Patel T, Prajapati K, Prosen KR, Reck F, Richie DL, Rico A, Sanderson MR, Satasia S, Sawyer WS, Selvarajah J, Shah N, Shanghavi K, Shu W, Thompson KV, Traebert M, Vala A, Vala L, Veselkov DA, Vo J, Wang M, Widya M, Williams SL, Xu Y, Yue Q, Zang R, Zhou B, Rivkin A. Topoisomerase Inhibitors Addressing Fluoroquinolone Resistance in Gram-Negative Bacteria. J Med Chem 2020; 63:7773-7816. [PMID: 32634310 DOI: 10.1021/acs.jmedchem.0c00347] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Since their discovery over 5 decades ago, quinolone antibiotics have found enormous success as broad spectrum agents that exert their activity through dual inhibition of bacterial DNA gyrase and topoisomerase IV. Increasing rates of resistance, driven largely by target-based mutations in the GyrA/ParC quinolone resistance determining region, have eroded the utility and threaten the future use of this vital class of antibiotics. Herein we describe the discovery and optimization of a series of 4-(aminomethyl)quinolin-2(1H)-ones, exemplified by 34, that inhibit bacterial DNA gyrase and topoisomerase IV and display potent activity against ciprofloxacin-resistant Gram-negative pathogens. X-ray crystallography reveals that 34 occupies the classical quinolone binding site in the topoisomerase IV-DNA cleavage complex but does not form significant contacts with residues in the quinolone resistance determining region.
Collapse
Affiliation(s)
- Colin K Skepper
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Duncan Armstrong
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Carl J Balibar
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Daniel Bauer
- Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Cornelia Bellamacina
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Bret M Benton
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Dirksen Bussiere
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Gianfranco De Pascale
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Javier De Vicente
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Charles R Dean
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Bhavesh Dhumale
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - L Mark Fisher
- Molecular and Clinical Sciences Research Institute, St George's University of London, London SW17 0RE, U.K
| | - John Fuller
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Mangesh Fulsunder
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Lauren M Holder
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Cheng Hu
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Bhavin Kantariya
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Guillaume Lapointe
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Jennifer A Leeds
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Xiaolin Li
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Peichao Lu
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Anatoli Lvov
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Sylvia Ma
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Shravanthi Madhavan
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Swapnil Malekar
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - David McKenney
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Wosenu Mergo
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Louis Metzger
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Heinz E Moser
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Daniel Mutnick
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Jonas Noeske
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Colin Osborne
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Ashish Patel
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Darshit Patel
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Tushar Patel
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Krunal Prajapati
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Katherine R Prosen
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Folkert Reck
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Daryl L Richie
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Alice Rico
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Mark R Sanderson
- Randall Centre for Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, U.K
| | - Shailesh Satasia
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - William S Sawyer
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Jogitha Selvarajah
- Molecular and Clinical Sciences Research Institute, St George's University of London, London SW17 0RE, U.K
| | - Nirav Shah
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Kartik Shanghavi
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Wei Shu
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Katherine V Thompson
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Martin Traebert
- Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Anand Vala
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Lakhan Vala
- Piramal Discovery Solutions, Pharmaceutical Special Economic Zone, Sarkhej Bavla Highway, Ahmedabad, Gujarat 382213, India
| | - Dennis A Veselkov
- Randall Centre for Cell and Molecular Biophysics, King's College, Guy's Campus, London Bridge, London SE1 1UL, U.K
| | - Jason Vo
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Michael Wang
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Marcella Widya
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Sarah L Williams
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Yongjin Xu
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Qin Yue
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Richard Zang
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Bo Zhou
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| | - Alexey Rivkin
- Novartis Institutes for BioMedical Research, Emeryville, California 94608, United States
| |
Collapse
|
4
|
McDowell LL, Quinn CL, Leeds JA, Silverman JA, Silver LL. Perspective on Antibacterial Lead Identification Challenges and the Role of Hypothesis-Driven Strategies. SLAS Discov 2020; 24:440-456. [PMID: 30890054 DOI: 10.1177/2472555218818786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
For the past three decades, the pharmaceutical industry has undertaken many diverse approaches to discover novel antibiotics, with limited success. We have witnessed and personally experienced many mistakes, hurdles, and dead ends that have derailed projects and discouraged scientists and business leaders. Of the many factors that affect the outcomes of screening campaigns, a lack of understanding of the properties that drive efflux and permeability requirements across species has been a major barrier for advancing hits to leads. Hits that possess bacterial spectrum have seldom also possessed druglike properties required for developability and safety. Persistence in solving these two key barriers is necessary for the reinvestment into discovering antibacterial agents. This perspective narrates our experience in antibacterial discovery-our lessons learned about antibacterial challenges as well as best practices for screening strategies. One of the tenets that guides us is that drug discovery is a hypothesis-driven science. Application of this principle, at all steps in the antibacterial discovery process, should improve decision making and possibly the odds of what has become, in recent decades, an increasingly challenging endeavor with dwindling success rates.
Collapse
Affiliation(s)
- Laura L McDowell
- 1 Novartis Institutes for Biomedical Research, Emeryville, CA, USA
| | | | - Jennifer A Leeds
- 1 Novartis Institutes for Biomedical Research, Emeryville, CA, USA
| | | | | |
Collapse
|
5
|
Tian H, Six DA, Krucker T, Leeds JA, Winograd N. Subcellular Chemical Imaging of Antibiotics in Single Bacteria Using C 60-Secondary Ion Mass Spectrometry. Anal Chem 2017; 89:5050-5057. [PMID: 28332827 PMCID: PMC5415874 DOI: 10.1021/acs.analchem.7b00466] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/23/2017] [Indexed: 12/20/2022]
Abstract
The inherent difficulty of discovering new and effective antibacterials and the rapid development of resistance particularly in Gram-negative bacteria, illustrates the urgent need for new methods that enable rational drug design. Here we report the development of 3D imaging cluster Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) as a label-free approach to chemically map small molecules in aggregated and single Escherichia coli cells, with ∼300 nm spatial resolution and high chemical sensitivity. The feasibility of quantitative analysis was explored, and a nonlinear relationship between treatment dose and signal for tetracycline and ampicillin, two clinically used antibacterials, was observed. The methodology was further validated by the observation of reduction in tetracycline accumulation in an E. coli strain expressing the tetracycline-specific efflux pump (TetA) compared to the isogenic control. This study serves as a proof-of-concept for a new strategy for chemical imaging at the nanoscale and has the potential to aid discovery of new antibacterials.
Collapse
Affiliation(s)
- Hua Tian
- Department
of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - David A. Six
- Novartis
Institutes
for BioMedical Research, Inc., 5300
Chiron Way, Emeryville, California 94608-2916, United States
| | - Thomas Krucker
- Novartis
Institutes
for BioMedical Research, Inc., 5300
Chiron Way, Emeryville, California 94608-2916, United States
| | - Jennifer A. Leeds
- Novartis
Institutes
for BioMedical Research, Inc., 5300
Chiron Way, Emeryville, California 94608-2916, United States
| | - Nicholas Winograd
- Department
of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| |
Collapse
|
6
|
LaMarche MJ, Leeds JA, Brewer J, Dean K, Ding J, Dzink-Fox J, Gamber G, Jain A, Kerrigan R, Krastel P, Lee K, Lombardo F, McKenney D, Neckermann G, Osborne C, Palestrant D, Patane MA, Rann EM, Robinson Z, Schmitt E, Stams T, Tiamfook S, Yu D, Whitehead L. Antibacterial and Solubility Optimization of Thiomuracin A. J Med Chem 2016; 59:6920-8. [DOI: 10.1021/acs.jmedchem.6b00726] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
| | - Jennifer A. Leeds
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | | | | | | | - Joanne Dzink-Fox
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | | | | | | | - Philipp Krastel
- Natural Products
Unit, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | | | | - David McKenney
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | - Georg Neckermann
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | - Colin Osborne
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | | | | | | | | | - Esther Schmitt
- Natural Products
Unit, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | | - Stacey Tiamfook
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | - Donghui Yu
- Infectious
Disease Area, Novartis Institutes for Biomedical Research, Emeryville, California 94608, United States
| | | |
Collapse
|
7
|
Leeds JA. Antibacterials Developed to Target a Single Organism: Mechanisms and Frequencies of Reduced Susceptibility to the Novel Anti-Clostridium difficile Compounds Fidaxomicin and LFF571. Cold Spring Harb Perspect Med 2016; 6:a025445. [PMID: 26834162 PMCID: PMC4743069 DOI: 10.1101/cshperspect.a025445] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Clostridium difficile is the most common cause of antibacterial-associated diarrhea. Clear clinical presentation and rapid diagnostics enable targeted therapy for C. difficile infection (CDI) to start quickly. CDI treatment includes metronidazole and vancomycin (VAN). Despite decades of use for CDI, no clinically meaningful resistance to either agent has emerged. Fidaxomicin (FDX), an RNA polymerase inhibitor, is also approved to treat CDI. Mutants with reduced susceptibility to FDX have been selected in vitro by single and multistep methods. Strains with elevated FDX minimum inhibitory concentrations (MICs) were also identified from FDX-treated patients in clinical trials. LFF571 is an exploratory agent that inhibits EF-Tu. In a proof-of-concept study, LFF571 was safe and effective for treating CDI. Spontaneous mutants with reduced susceptibility to LFF571 were selected in vitro in a single step, but not via serial passage. Although there are several agents in development for treatment of CDI, this review summarizes the frequencies and mechanisms of C. difficile mutants displaying reduced susceptibility to FDX or LFF71.
Collapse
Affiliation(s)
- Jennifer A Leeds
- Infectious Disease Area, Novartis Institutes for BioMedical Research, Emeryville, California 94608
| |
Collapse
|
8
|
Ross AG, Benton BM, Chin D, De Pascale G, Fuller J, Leeds JA, Reck F, Richie DL, Vo J, LaMarche MJ. Synthesis of ciprofloxacin dimers for evaluation of bacterial permeability in atypical chemical space. Bioorg Med Chem Lett 2015; 25:3468-75. [PMID: 26189081 DOI: 10.1016/j.bmcl.2015.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 11/19/2022]
Abstract
We describe the synthesis and evaluation of a library of variably-linked ciprofloxacin dimers. These structures unify and expand on the use of fluoroquinolones as probes throughout the antibiotic literature. A dimeric analog (19) showed enhanced inhibition of its intracellular target (DNA gyrase), and translation to antibacterial activity in whole cells was demonstrated. Overall, cell permeation was governed by physicochemical properties and bacterial type. A principal component analysis demonstrated that the dimers occupy a unique and privileged region of chemical space most similar to the macrolide class of antibiotics.
Collapse
Affiliation(s)
- Audrey G Ross
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Bret M Benton
- Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Donovan Chin
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | - John Fuller
- Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Jennifer A Leeds
- Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Folkert Reck
- Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Daryl L Richie
- Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Jason Vo
- Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | | |
Collapse
|
9
|
Mullane K, Lee C, Bressler A, Buitrago M, Weiss K, Dabovic K, Praestgaard J, Leeds JA, Blais J, Pertel P. Multicenter, randomized clinical trial to compare the safety and efficacy of LFF571 and vancomycin for Clostridium difficile infections. Antimicrob Agents Chemother 2015; 59:1435-40. [PMID: 25534727 PMCID: PMC4325808 DOI: 10.1128/aac.04251-14] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/13/2014] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile infection causes serious diarrheal disease. Although several drugs are available for treatment, including vancomycin, recurrences remain a problem. LFF571 is a semisynthetic thiopeptide with potency against C. difficile in vitro. In this phase 2 exploratory study, we compared the safety and efficacy (based on a noninferiority analysis) of LFF571 to those of vancomycin used in adults with primary episodes or first recurrences of moderate C. difficile infection. Patients were randomized to receive 200 mg of LFF571 or 125 mg of vancomycin four times daily for 10 days. The primary endpoint was the proportion of clinical cures at the end of therapy in the per-protocol population. Secondary endpoints included clinical cures at the end of therapy in the modified intent-to-treat (mITT) population, the time to diarrhea resolution, and the recurrence rate. Seventy-two patients were randomized, with 46 assigned to receive LFF571. Based on the protocol-specified definition, the rate of clinical cure for LFF571 (90.6%) was noninferior to that of vancomycin (78.3%). The 30-day sustained cure rates for LFF571 and vancomycin were 56.7% and 65.0%, respectively, in the per-protocol population and 58.7% and 60.0%, respectively, in the modified intent-to-treat population. Using toxin-confirmed cases only, the recurrence rates were lower for LFF571 (19% versus 25% for vancomycin in the per-protocol population). LFF571 was generally safe and well tolerated. The incidence of adverse events (AEs) was higher for LFF571 (76.1% versus 69.2% for vancomycin), although more AEs in the vancomycin group were suspected to be related to the study drug (38.5% versus 32.6% for LFF571). One patient receiving LFF571 discontinued the study due to an AE. (This study has been registered at ClinicalTrials.gov under registration no. NCT01232595.).
Collapse
Affiliation(s)
- Kathleen Mullane
- The University of Chicago Medicine, Section of Infectious Diseases and Global Health, Chicago, Illinois, USA
| | - Christine Lee
- St. Joseph's Healthcare Hamilton, Hamilton Regional Laboratory Medicine Program, McMaster University, Department of Pathology and Molecular Medicine, Hamilton, Ontario, Canada
| | - Adam Bressler
- Infectious Disease Specialists of Atlanta, Decatur, Georgia, USA
| | | | - Karl Weiss
- Université de Montréal, Département de Microbiologie et d'Infectiologie, Hôpital Maisonneuve-Rosemont, Montréal, Quebec, Canada
| | - Kristina Dabovic
- Novartis Institutes for BioMedical Research, Infectious Disease Area, East Hanover, New Jersey, USA
| | - Jens Praestgaard
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA
| | - Jennifer A Leeds
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Emeryville, California, USA
| | - Johanne Blais
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Emeryville, California, USA
| | - Peter Pertel
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Cambridge, Massachusetts, USA
| |
Collapse
|
10
|
Bhansali SG, Mullane K, Ting LSL, Leeds JA, Dabovic K, Praestgaard J, Pertel P. Pharmacokinetics of LFF571 and vancomycin in patients with moderate Clostridium difficile infections. Antimicrob Agents Chemother 2015; 59:1441-5. [PMID: 25534724 PMCID: PMC4325791 DOI: 10.1128/aac.04252-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 11/29/2014] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile infection causes diarrheal disease with potentially fatal complications. Although treatments are available, including vancomycin, metronidazole, and fidaxomicin, the recurrence of disease after therapy remains a problem. LFF571 is a novel thiopeptide antibacterial that shows in vitro potency against C. difficile that is comparable to or greater than that of other clinically used antibiotics. Here, we compare the pharmacokinetics (PK) of LFF571 and vancomycin in patients with C. difficile infection as part of an early efficacy study. This multicenter, randomized, evaluator-blind, and active-controlled study evaluated the safety, efficacy, and pharmacokinetics of LFF571 in adults with primary episodes or first relapses of moderate C. difficile infections. Patients were randomized to receive 200 mg of LFF571 or 125 mg of vancomycin four times daily for 10 days. The PK parameters were calculated from drug concentrations measured in serum and fecal samples. The systemic exposure following oral administration of 200 mg of LFF571 four times per day for 10 days in patients with C. difficile infection was limited. The highest LFF571 serum concentration observed was 41.7 ng/ml, whereas the levels in feces at the end of treatment were between 107 and 12,900 μg/g. In comparison, the peak vancomycin level observed in serum was considerably higher, at 2.73 μg/ml; the levels of vancomycin in feces were not measured. Similar to healthy volunteers, patients with C. difficile infections exhibited high fecal concentrations and low serum levels of LFF571. These results are consistent with the retention of LFF571 in the lumen of the gastrointestinal tract. (This study has been registered at ClinicalTrials.gov under registration no. NCT01232595.).
Collapse
Affiliation(s)
- Suraj G Bhansali
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA
| | - Kathleen Mullane
- The University of Chicago Medicine, Section of Infectious Diseases and Global Health, Chicago, Illinois, USA
| | - Lillian S L Ting
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA
| | - Jennifer A Leeds
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Emeryville, California, USA, East Hanover, New Jersey, USA, and Cambridge, Massachusetts, USA
| | - Kristina Dabovic
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Emeryville, East Hanover, New Jersey, USA
| | - Jens Praestgaard
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA
| | - Peter Pertel
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Cambridge, Massachusetts, USA
| |
Collapse
|
11
|
Sachdeva M, Leeds JA. Subinhibitory concentrations of LFF571 reduce toxin production by Clostridium difficile. Antimicrob Agents Chemother 2015; 59:1252-7. [PMID: 25512411 PMCID: PMC4335859 DOI: 10.1128/aac.04436-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/07/2014] [Indexed: 01/05/2023] Open
Abstract
LFF571 is a novel semisynthetic thiopeptide antibacterial that is undergoing investigation for safety and efficacy in patients with moderate Clostridium difficile infections. LFF571 inhibits bacterial protein synthesis by interacting with elongation factor Tu (EF-Tu) and interrupting complex formation between EF-Tu and aminoacyl-tRNA. Given this mechanism of action, we hypothesized that concentrations of LFF571 below those necessary to inhibit bacterial growth would reduce steady-state toxin levels in C. difficile cultures. We investigated C. difficile growth and toxin A and B levels in the presence of LFF571, fidaxomicin, vancomycin, and metronidazole. LFF571 led to strain-dependent effects on toxin production, including decreased toxin levels after treatment with subinhibitory concentrations, and more rapid declines in toxin production than in inhibition of colony formation. Fidaxomicin, which is an RNA synthesis inhibitor, conferred a similar pattern to LFF571 with respect to toxin levels versus viable cell counts. The incubation of two toxigenic C. difficile strains with subinhibitory concentrations of vancomycin, a cell wall synthesis inhibitor, increased toxin levels in the supernatant over those of untreated cultures. A similar phenomenon was observed with one metronidazole-treated strain of C. difficile. These studies indicate that LFF571 and fidaxomicin generally result in decreased C. difficile toxin levels in culture supernatants, whereas treatment of some strains with vancomycin or metronidazole had the potential to increase toxin levels. Although the relevance of these findings remains to be studied in patients, reducing toxin levels with sub-growth-inhibitory concentrations of an antibiotic is hypothesized to be beneficial in alleviating symptoms.
Collapse
Affiliation(s)
- Meena Sachdeva
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Emeryville, California, USA
| | - Jennifer A Leeds
- Novartis Institutes for BioMedical Research, Infectious Disease Area, Emeryville, California, USA
| |
Collapse
|
12
|
Leeds JA, Sachdeva M, Mullin S, Barnes SW, Ruzin A. In vitro selection, via serial passage, of Clostridium difficile mutants with reduced susceptibility to fidaxomicin or vancomycin. J Antimicrob Chemother 2014; 69:41-4. [PMID: 23887866 DOI: 10.1093/jac/dkt302] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Current treatments for Clostridium difficile infection include vancomycin, metronidazole and fidaxomicin. LFF571 is an experimental agent undergoing evaluation in humans for the treatment of moderate C. difficile infection. Reduced susceptibility of C. difficile to fidaxomicin or LFF571 in vitro can be mediated by single point mutations in genes encoding the targets, whereas the mechanism(s) mediating reduced susceptibility to vancomycin in vitro remains elusive. To further characterize mechanisms reducing susceptibility of C. difficile to vancomycin, fidaxomicin or LFF571 in vitro, selections via serial passage at low cell density were performed, followed by whole-genome sequencing. METHODS C. difficile strain ATCC 43255 and three clinical isolates were subjected to 10 passages on medium containing a range of concentrations of fidaxomicin, LFF571 or vancomycin. Genomic DNA from isolates with reduced susceptibility was sequenced using Illumina Whole Genome Sequencing. RESULTS Clones exhibiting decreased susceptibility to fidaxomicin harboured mutations in rpoB and CD22120 (marR homologue). Clones exhibiting decreased susceptibility to vancomycin harboured mutations in rpoC and also in CD2725, CD3659 and sdaB, which encode a putative N-acetylglucosamine transferase, exonuclease and l-serine deaminase, respectively. All mutations resulted in non-synonymous substitutions. No clones with reduced susceptibility to LFF571 were selected in this study. CONCLUSIONS Reduced susceptibility to fidaxomicin and vancomycin was associated with mutations mediating target modifications (RNA polymerase and cell wall, respectively), as well as with mutations that may contribute to reduced susceptibility via other mechanisms. The MIC of LFF571 was unaffected for those mutants with reduced susceptibility to fidaxomicin or vancomycin.
Collapse
Affiliation(s)
- Jennifer A Leeds
- Novartis Institutes for BioMedical Research, 4560 Horton Street, Emeryville, CA 94608, USA
| | | | | | | | | |
Collapse
|
13
|
LaMarche MJ, Leeds JA, Dzink-Fox J, Gangl E, Krastel P, Neckermann G, Palestrant D, Patane MA, Rann EM, Tiamfook S, Yu D. Correction to Antibiotic Optimization and Chemical Structure Stabilization of Thiomuracin A. J Med Chem 2013. [DOI: 10.1021/jm4000402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
14
|
Ting LSL, Praestgaard J, Grunenberg N, Yang JC, Leeds JA, Pertel P. A first-in-human, randomized, double-blind, placebo-controlled, single- and multiple-ascending oral dose study to assess the safety and tolerability of LFF571 in healthy volunteers. Antimicrob Agents Chemother 2012; 56:5946-51. [PMID: 22964250 PMCID: PMC3486596 DOI: 10.1128/aac.00867-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 09/01/2012] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile is the leading cause of hospital-acquired infectious diarrhea. LFF571 is a novel inhibitor of the prokaryotic translation elongation factor Tu and is active against a range of bacterial species, including C. difficile. This first-in-human study investigated the safety and pharmacokinetics of single and multiple ascending oral doses of LFF571 in healthy subjects. This was a randomized, double-blind, placebo-controlled study. Except for one cohort, LFF571 was given with a high-fat meal to all single-dose cohorts (25 mg, 100 mg, 400 mg, and 1,000 mg). In the multiple-dose cohorts (25 mg, 100 mg, or 200 mg every 6 h for 10 days), LFF571 was given without regard to food. A total of 56 subjects completed the study, with 32 and 25 receiving single and multiple doses, respectively. There were no deaths, no serious adverse events, and no subject withdrawals due to an adverse event. The most common adverse event was diarrhea; gastrointestinal pain or distension was also noted. Diarrhea did not develop more frequently among subjects who received LFF571 than among those who received a placebo. LFF571 had limited systemic exposure and high steady-state fecal concentrations. The highest concentration of LFF571 in serum (3.2 ng/ml) was observed after the last dose in a subject who received 200 mg every 6 h for 10 days. LFF571 was generally safe and well tolerated in single and multiple oral doses in healthy subjects. The minimal serum and high fecal concentrations support the further development of LFF571 for the treatment of C. difficile infections.
Collapse
Affiliation(s)
- Lillian S. L. Ting
- Novartis Institutes for BioMedical Research, East Hanover, New Jersey, USA
| | | | - Nicole Grunenberg
- Charles River Clinical Services Northwest, Inc., Tacoma, Washington, USA
| | - Jenny C. Yang
- Novartis Institutes for BioMedical Research, East Hanover, New Jersey, USA
| | - Jennifer A. Leeds
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Peter Pertel
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, USA
| |
Collapse
|
15
|
Trzasko A, Leeds JA, Praestgaard J, LaMarche MJ, McKenney D. Efficacy of LFF571 in a hamster model of Clostridium difficile infection. Antimicrob Agents Chemother 2012; 56:4459-62. [PMID: 22644020 PMCID: PMC3421564 DOI: 10.1128/aac.06355-11] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 05/17/2012] [Indexed: 01/20/2023] Open
Abstract
LFF571 is a novel semisynthetic thiopeptide antibiotic with potent activity against a variety of Gram-positive pathogens, including Clostridium difficile. In vivo efficacy of LFF571 was compared to vancomycin in a hamster model of C. difficile infection (CDI). Infection was induced in Golden Syrian hamsters using a toxigenic strain of C. difficile. Treatment started 24 h postinfection and consisted of saline, vancomycin, or LFF571. Cox regression was used to analyze survival data from a cohort of animals evaluated across seven serial experimental groups treated with vancomycin at 20 mg/kg, LFF571 at 5 mg/kg, or vehicle alone. Survival was right censored; animals were not observed beyond day 21. At death or end of study, cecal contents were tested for C. difficile toxins A and B. In summary, the data showed that 5 mg/kg LFF571 decreased the risk of death by 79% (P < 0.0001) and 69% (P = 0.0022) compared with saline and 20 mg/kg vancomycin, respectively. Further analysis of the pooled data indicated that the survival benefit of LFF571 treatment at 5 mg/kg compared to vancomycin at 20 mg/kg was due primarily to a decrease in the risk of recurrence after end of treatment. Animals successfully treated with LFF571 or vancomycin had no detectable C. difficile toxin. Overall, LFF571 was more efficacious at the end of the study, at a lower dose, and with fewer recurrences, than vancomycin in the hamster model of CDI. LFF571 is being assessed in humans for safety and efficacy in the treatment of C. difficile infections.
Collapse
Affiliation(s)
- Anna Trzasko
- Novartis Institutes for Biomedical Research, Infectious Disease Area, Emeryville, California, USA
| | - Jennifer A. Leeds
- Novartis Institutes for Biomedical Research, Infectious Disease Area, Emeryville, California, USA
| | | | | | - David McKenney
- Novartis Institutes for Biomedical Research, Infectious Disease Area, Emeryville, California, USA
| |
Collapse
|
16
|
Leeds JA, Sachdeva M, Mullin S, Dzink-Fox J, Lamarche MJ. Mechanism of action of and mechanism of reduced susceptibility to the novel anti-Clostridium difficile compound LFF571. Antimicrob Agents Chemother 2012; 56:4463-5. [PMID: 22644023 PMCID: PMC3421628 DOI: 10.1128/aac.06354-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 03/06/2012] [Indexed: 01/07/2023] Open
Abstract
LFF571 is a novel semisynthetic thiopeptide and potent inhibitor of Gram-positive bacteria. We report that the antibacterial activity of LFF571 against Clostridium difficile is due to inhibition of translation. Single-step mutants of C. difficile with reduced susceptibility to LFF571 were selected at frequencies of <4.5 × 10(-11) to 1.2 × 10(-9). Sequencing revealed a G260E substitution in the thiopeptide-binding pocket of elongation factor Tu. Importantly, this mutation did not confer cross-resistance to clinically used antimicrobials. These results support the development of LFF571 as a treatment for C. difficile infection.
Collapse
Affiliation(s)
- J A Leeds
- Novartis Institutes for Biomedical Research, Infectious Disease Area, Emeryville, California, USA.
| | | | | | | | | |
Collapse
|
17
|
LaMarche MJ, Leeds JA, Dzink-Fox J, Gangl E, Krastel P, Neckermann G, Palestrant D, Patane MA, Rann EM, Tiamfook S, Yu D. Antibiotic optimization and chemical structure stabilization of thiomuracin A. J Med Chem 2012; 55:6934-41. [PMID: 22812377 DOI: 10.1021/jm300783c] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Synthetic studies of the antimicrobial secondary metabolite thiomuracin A (1) were initiated to improve chemical stability and physicochemical properties. Functional group modifications of 1 included removing the C2-C7 side chain, derivatizing the C84 epoxide region, and altering the C44 hydroxyphenylalanine motif. The resulting derivatives simplified and stabilized the chemical structure and were evaluated for antibacterial activity relative to 1. The simplified structure and improved organic solubility of the derivatives facilitated isolation yields from fermentation broths and simplified the procedures involved for the process. These advancements increased material supply for continued medicinal chemistry optimization and culminated in the identification of 2, a structurally simplified and chemically stable analogue of 1 which retained potent antibiotic activity.
Collapse
Affiliation(s)
- Matthew J LaMarche
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139, United States.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
LaMarche MJ, Leeds JA, Amaral A, Brewer JT, Bushell SM, Deng G, Dewhurst JM, Ding J, Dzink-Fox J, Gamber G, Jain A, Lee K, Lee L, Lister T, McKenney D, Mullin S, Osborne C, Palestrant D, Patane MA, Rann EM, Sachdeva M, Shao J, Tiamfook S, Trzasko A, Whitehead L, Yifru A, Yu D, Yan W, Zhu Q. Discovery of LFF571: an investigational agent for Clostridium difficile infection. J Med Chem 2012; 55:2376-87. [PMID: 22315981 DOI: 10.1021/jm201685h] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Clostridium difficile (C. difficile) is a Gram positive, anaerobic bacterium that infects the lumen of the large intestine and produces toxins. This results in a range of syndromes from mild diarrhea to severe toxic megacolon and death. Alarmingly, the prevalence and severity of C. difficile infection are increasing; thus, associated morbidity and mortality rates are rising. 4-Aminothiazolyl analogues of the antibiotic natural product GE2270 A (1) were designed, synthesized, and optimized for the treatment of C. difficile infection. The medicinal chemistry effort focused on enhancing aqueous solubility relative to that of the natural product and previous development candidates (2, 3) and improving antibacterial activity. Structure-activity relationships, cocrystallographic interactions, pharmacokinetics, and efficacy in animal models of infection were characterized. These studies identified a series of dicarboxylic acid derivatives, which enhanced solubility/efficacy profile by several orders of magnitude compared to previously studied compounds and led to the selection of LFF571 (4) as an investigational new drug for treating C. difficile infection.
Collapse
Affiliation(s)
- Matthew J LaMarche
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, 250 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
LaMarche MJ, Leeds JA, Amaral K, Brewer JT, Bushell SM, Dewhurst JM, Dzink-Fox J, Gangl E, Goldovitz J, Jain A, Mullin S, Neckermann G, Osborne C, Palestrant D, Patane MA, Rann EM, Sachdeva M, Shao J, Tiamfook S, Whitehead L, Yu D. Antibacterial Optimization of 4-Aminothiazolyl Analogues of the Natural Product GE2270 A: Identification of the Cycloalkylcarboxylic Acids. J Med Chem 2011; 54:8099-109. [DOI: 10.1021/jm200938f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Akash Jain
- Chemical and Pharmaceutical
Profiling, Novartis Pharmaceuticals, Cambridge,
Massachusetts 02139, United States
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
LaMarche MJ, Leeds JA, Dzink-Fox J, Mullin S, Patane MA, Rann EM, Tiamfook S. 4-Aminothiazolyl analogs of GE2270 A: Design, synthesis and evaluation of imidazole analogs. Bioorg Med Chem Lett 2011; 21:3210-5. [DOI: 10.1016/j.bmcl.2011.04.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 04/12/2011] [Indexed: 11/29/2022]
|
21
|
LaMarche MJ, Leeds JA, Dzink-Fox J, Gunderson K, Krastel P, Memmert K, Patane MA, Rann EM, Schmitt E, Tiamfook S, Wang B. 4-Aminothiazolyl Analogues of GE2270 A: Antibacterial Lead Finding. J Med Chem 2011; 54:2517-21. [DOI: 10.1021/jm101602q] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - Philipp Krastel
- Natural Products Unit, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Klaus Memmert
- Natural Products Unit, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | | | | - Esther Schmitt
- Natural Products Unit, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | | | |
Collapse
|
22
|
Miller K, Dunsmore CJ, Leeds JA, Patching SG, Sachdeva M, Blake KL, Stubbings WJ, Simmons KJ, Henderson PJF, De Los Angeles J, Fishwick CWG, Chopra I. Benzothioxalone derivatives as novel inhibitors of UDP-N-acetylglucosamine enolpyruvyl transferases (MurA and MurZ). J Antimicrob Chemother 2010; 65:2566-73. [PMID: 20861142 DOI: 10.1093/jac/dkq349] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES We sought to identify and characterize new inhibitors of MurA and MurZ, which are enzymes involved in the early stages of bacterial peptidoglycan synthesis. METHODS A library of ∼650 000 compounds was screened for inhibitors of Escherichia coli MurA in an endpoint assay measuring release of inorganic phosphate from phosphoenolpyruvate. Hits were validated by determining the concentrations required for 50% inhibition (IC(50)) of MurA from E. coli and MurA/MurZ from Staphylococcus aureus. The mode of action of selected inhibitors was explored by examining the reversibility of MurA inhibition, the binding of a radiolabelled inhibitor to MurA proteins and through docking studies. Inhibitors were further characterized by determining their antibacterial activity against E. coli and S. aureus. RESULTS Benzothioxalone derivatives were identified that inhibited MurA from E. coli and MurA/MurZ from S. aureus with IC(50) values between 0.25 and 51 µM. Several inhibitors also exhibited activity against S. aureus with MICs in the range 4-128 mg/L. Inhibition of MurA was irreversible and a radiolabelled inhibitor from this compound class displayed stoichiometric binding to the enzyme, which was displaced by dithiothreitol. Binding was undetectable with a C115D mutant MurA protein. CONCLUSIONS The results suggest a mode of action for the benzothioxalones that involves the formation of a disulfide bond with MurA/MurZ, via attack from an active site cysteine on the thioxalone ring carbonyl group, followed by ring opening to yield an S-acylated protein. The proposed covalent mode of action may prove useful in the design of new antibacterial agents.
Collapse
Affiliation(s)
- Keith Miller
- Antimicrobial Research Centre, University of Leeds, Leeds, UK
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Leeds JA, Garrett PB, Newman JM. Assessing Impacts of Hydropattern Restoration of an Overdrained Wetland on Soil Nutrients, Vegetation and Fire. Restor Ecol 2009. [DOI: 10.1111/j.1526-100x.2008.00381.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
24
|
Morris RP, Leeds JA, Naegeli HU, Oberer L, Memmert K, Weber E, LaMarche MJ, Parker CN, Burrer N, Esterow S, Hein AE, Schmitt EK, Krastel P. Ribosomally synthesized thiopeptide antibiotics targeting elongation factor Tu. J Am Chem Soc 2009; 131:5946-55. [PMID: 19338336 DOI: 10.1021/ja900488a] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We identified the thiomuracins, a novel family of thiopeptides produced by a rare-actinomycete bacterium typed as a Nonomuraea species, via a screen for inhibition of growth of the bacterial pathogen Staphylococcus aureus. Thiopeptides are a class of macrocyclic, highly modified peptides that are decorated by thiazoles and defined by a central six-membered heterocyclic ring system. Mining the genomes of thiopeptide-producing strains revealed the elusive biosynthetic route for this class of antibiotics. The thiopeptides are chromosomally encoded, ribosomally synthesized proteins, and isolation of gene clusters for production of thiomuracin and the related thiopeptide GE2270A revealed the post-translational machinery required for maturation. The target of the thiomuracins was identified as bacterial Elongation Factor Tu (EF-Tu). In addition to potently inhibiting a target that is unexploited by marketed human therapeutics, the thiomuracins have a low propensity for selecting for antibiotic resistance and confer no measurable cross-resistance to antibiotics in clinical use.
Collapse
Affiliation(s)
- Rowan P Morris
- Natural Products Unit, Novartis Institutes for BioMedical Research, Basel, 4056, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Blake KL, O'Neill AJ, Mengin-Lecreulx D, Henderson PJF, Bostock JM, Dunsmore CJ, Simmons KJ, Fishwick CWG, Leeds JA, Chopra I. The nature of Staphylococcus aureus MurA and MurZ and approaches for detection of peptidoglycan biosynthesis inhibitors. Mol Microbiol 2009; 72:335-43. [PMID: 19298367 DOI: 10.1111/j.1365-2958.2009.06648.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Staphylococcus aureus and a number of other Gram-positive organisms harbour two genes (murA and murZ) encoding UDP-N-acetylglucosamine enolpyruvyl transferase activity for catalysing the first committed step of peptidoglycan biosynthesis. We independently inactivated murA and murZ in S. aureus and established that either can sustain viability. Purification and characterization of the MurA and MurZ enzymes indicated that they are biochemically similar in vitro, consistent with similar overall structures predicted for the isozymes by molecular modelling. Nevertheless, MurA appears to be the primary enzyme utilized in the staphylococcal cell. Accordingly, murA expression was approximately five times greater than murZ expression during exponential growth, and the peptidoglycan content of S. aureus was reduced by approximately 25% following inactivation of murA, but remained almost unchanged following inactivation of murZ. Despite low level expression during normal growth, murZ expression was strongly induced (up to sixfold) following exposure to inhibitors of peptidoglycan biosynthesis, which was not observed for murA. Strains generated in this study were validated as potential tools for identifying novel anti-staphylococcal agents targeting peptidoglycan biosynthesis using known inhibitors of the pathway.
Collapse
Affiliation(s)
- Katy L Blake
- Institute of Molecular and Cellular Biology and Antimicrobial Research Centre, University of Leeds, Leeds, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Dunsmore CJ, Miller K, Blake KL, Patching SG, Henderson PJF, Garnett JA, Stubbings WJ, Phillips SEV, Palestrant DJ, Angeles JDL, Leeds JA, Chopra I, Fishwick CWG. 2-Aminotetralones: novel inhibitors of MurA and MurZ. Bioorg Med Chem Lett 2008; 18:1730-4. [PMID: 18261901 DOI: 10.1016/j.bmcl.2008.01.089] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 01/11/2008] [Accepted: 01/12/2008] [Indexed: 10/22/2022]
Abstract
Several 2-aminotetralones were identified as novel inhibitors of the bacterial enzymes MurA and MurZ. A number of these inhibitors demonstrated antibacterial activity against Staphylococcus aureus and Escherichia coli with MICs in the range 8-128 microg/ml. Based on structure-activity relationships we propose that the alpha-aminoketone functionality is responsible for the inhibitory activity and evidence is provided to support a covalent mode of action involving the C115 thiol group of MurA/MurZ.
Collapse
Affiliation(s)
- Colin J Dunsmore
- School of Chemistry and Antimicrobial Research Centre, University of Leeds, Leeds LS2 9JT, UK
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Dean CR, Narayan S, Richards J, Daigle DM, Esterow S, Leeds JA, Kamp H, Puyang X, Wiedmann B, Mueller D, Voshol H, van Oostrum J, Wall D, Koehn J, Dzink-Fox J, Ryder NS. Reduced susceptibility of Haemophilus influenzae to the peptide deformylase inhibitor LBM415 can result from target protein overexpression due to amplified chromosomal def gene copy number. Antimicrob Agents Chemother 2007; 51:1004-10. [PMID: 17220413 PMCID: PMC1803149 DOI: 10.1128/aac.01103-06] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous genetic analysis of Haemophilus influenzae revealed two mechanisms associated with decreased susceptibility to the novel peptide deformylase inhibitor LBM415: AcrAB-TolC-mediated efflux and Fmt bypass, resulting from mutations in the pump repressor gene acrR and in the fmt gene, respectively. We have isolated an additional mutant, CDS23 (LBM415 MIC, 64 microg/ml versus 4 microg/ml against the parent strain NB65044) that lacks mutations in the acrR or fmt structural genes or in the gene encoding Def, the intracellular target of LBM415. Western immunoblot analysis, two-dimensional gel electrophoresis, and tryptic digestion combined with mass spectrometric identification showed that the Def protein was highly overexpressed in the mutant strain. Consistent with this, real-time reverse transcription-PCR revealed a significant increase in def transcript titer. No mutations were found in the region upstream of def that might account for altered expression; however, pulsed-field gel electrophoresis suggested that a genetic rearrangement of the region containing def had occurred. Using a combination of PCR, sequencing, and Southern blot analyses, it was determined that the def gene had undergone copy number amplification, explaining the high level of target protein expression. Inactivation of the AcrAB-TolC efflux pump in this mutant increased susceptibility 16-fold, highlighting the role of efflux in exacerbating the overall reduced susceptibility resulting from target overexpression.
Collapse
Affiliation(s)
- Charles R Dean
- Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Abstract
Peptide deformylase (PDF) is among the few antibacterial targets against which novel synthetic inhibitors derived from rationally designed, mechanism-based libraries have progressed into clinical trials. Nearly two decades of investigation led to this milestone; however, increased understanding of resistance to these compounds and recent evidence of catalytically active human mitochondrial PDF impact the perception of PDF as an antibacterial target. There are also many unanswered questions concerning the mechanism of action of PDF inhibitors and the necessity of the formylation/deformylation cycle in bacteria. Nevertheless, the experience gained from research on PDF serves as perhaps the best current illustration of the risks and possibilities associated with novel target-based antibiotic discovery.
Collapse
Affiliation(s)
- Jennifer A Leeds
- Infectious Diseases Area, Novartis Institutes for BioMedical Research, Cambridge MA 02139, USA.
| | | |
Collapse
|
29
|
Watters AA, Jones RN, Leeds JA, Denys G, Sader HS, Fritsche TR. Antimicrobial activity of a novel peptide deformylase inhibitor, LBM415, tested against respiratory tract and cutaneous infection pathogens: a global surveillance report (2003-2004). J Antimicrob Chemother 2006; 57:914-23. [PMID: 16549511 DOI: 10.1093/jac/dkl093] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES To evaluate the spectrum of activity and potency of LBM415, the first of the peptide deformylase inhibitor (PDFI) class to be developed for treatment of community-acquired respiratory tract infections and uncomplicated skin and soft tissue infections (uSSTI), against a large, contemporary international collection of targeted pathogens collected during 2003-2004. METHODS A total of 21,636 isolates were tested by reference broth microdilution methods as part of a longitudinal international antimicrobial resistance surveillance study. Characteristics of the organism collection included resistance to oxacillin among 35.0% of Staphylococcus aureus and 76.0% of coagulase-negative staphylococci (CoNS); resistance to penicillin (MIC > or = 2 mg/L) among 18.0% of Streptococcus pneumoniae; vancomycin resistance among 20.0% of Enterococcus spp. and ampicillin resistance among 22.0% of Haemophilus influenzae. RESULTS LBM415 displayed potent activity against staphylococci, streptococci, Enterococcus faecium and Moraxella catarrhalis, with > or = 99.0% of strains being inhibited at < or = 4 mg/L; 97.0% of Enterococcus faecalis isolates and 92.0% of H. influenzae isolates were also inhibited at this concentration. Seventy-seven percent of Burkholderia cepacia and 82.0% of Stenotrophomonas maltophilia were inhibited at < or = 8 mg/L. No differences in LBM415 activity against S. aureus, CoNS, S. pneumoniae, Enterococcus spp. and H. influenzae were detected for subsets susceptible or resistant to antimicrobials such as oxacillin, penicillin, ampicillin, macrolides, vancomycin and fluoroquinolones. While regional differences were apparent with some comparator agents, sensitivity to LBM415 did not vary significantly among strains from the various geographic areas sampled. One isolate of S. aureus displayed high-level resistance to LBM415 owing to multiple sequence changes in resistance phenotype genes (defB and fmt), despite the absence of the compound in clinical practice. This isolate remained susceptible to all other antimicrobials tested except for penicillin. CONCLUSIONS With few differences detected among strains from various geographic regions, the first PDFI class agent to enter clinical development has consistently demonstrated a broad spectrum of activity against commonly isolated pathogens associated with uncomplicated respiratory and cutaneous infections. These compounds represent a significant therapeutic advance owing to their novel mechanism of action and antibacterial spectrum, including activity against resistant organisms, should pharmacokinetic and pharmacodynamic parameters support their continued development. Given the detection of a pre-existing PDFI-resistant isolate of S. aureus as demonstrated here, surveillance for resistance among the PDFI-targeted pathogens following introduction of this class of agent into clinical usage will be an important component of future studies.
Collapse
Affiliation(s)
- Amy A Watters
- JMI Laboratories, 345 Beaver Kreek Centre, Suite A, North Liberty, IA 52317, USA.
| | | | | | | | | | | |
Collapse
|
30
|
Leeds JA, Schmitt EK, Krastel P. Recent developments in antibacterial drug discovery: microbe-derived natural products – from collection to the clinic. Expert Opin Investig Drugs 2006; 15:211-26. [PMID: 16503759 DOI: 10.1517/13543784.15.3.211] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The pharmaceutical industry has historically relied on nature to provide compounds for antibacterial drug discovery. In recent years, several pharmaceutical companies have scaled back their efforts in natural product research. Nevertheless, the screening of natural products for antibacterial activity continues to provide excellent sources of biologically and chemically informative leads for new drugs. New technologies in high-throughput cultivation, genetic approaches to biodiversity and discovery of relatively untapped sources of natural products are expanding the ability to find novel, potent and highly selective antibacterial structures. Advances in purification, dereplication and structure elucidation, combined with the ability to chemically or biologically derivatise hits, aim to make the timeline for natural product-derived drug discovery similar or shorter than that expected for small synthetic molecules. This review addresses the strengths and shortcomings of technologies focused on microbe-derived natural products for antibacterial drug discovery and stresses the need for commitment to these approaches in order to achieve the goal of delivering safe, efficacious and high-quality medicines in the long run.
Collapse
Affiliation(s)
- Jennifer A Leeds
- Infectious Diseases Area, Novartis Institutes for BioMedical Research, Cambridge, MA 02139, USA.
| | | | | |
Collapse
|
31
|
Hoet RM, Cohen EH, Kent RB, Rookey K, Schoonbroodt S, Hogan S, Rem L, Frans N, Daukandt M, Pieters H, van Hegelsom R, Neer NCV, Nastri HG, Rondon IJ, Leeds JA, Hufton SE, Huang L, Kashin I, Devlin M, Kuang G, Steukers M, Viswanathan M, Nixon AE, Sexton DJ, Hoogenboom HR, Ladner RC. Generation of high-affinity human antibodies by combining donor-derived and synthetic complementarity-determining-region diversity. Nat Biotechnol 2005; 23:344-8. [PMID: 15723048 DOI: 10.1038/nbt1067] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2004] [Accepted: 01/05/2005] [Indexed: 11/09/2022]
Abstract
Combinatorial libraries of rearranged hypervariable V(H) and V(L) sequences from nonimmunized human donors contain antigen specificities, including anti-self reactivities, created by random pairing of V(H)s and V(L)s. Somatic hypermutation of immunoglobulin genes, however, is critical in the generation of high-affinity antibodies in vivo and occurs only after immunization. Thus, in combinatorial phage display libraries from nonimmunized donors, high-affinity antibodies are rarely found. Lengthy in vitro affinity maturation is often needed to improve antibodies from such libraries. We report the construction of human Fab libraries having a unique combination of immunoglobulin sequences captured from human donors and synthetic diversity in key antigen contact sites in heavy-chain complementarity-determining regions 1 and 2. The success of this strategy is demonstrated by identifying many monovalent Fabs against multiple therapeutic targets that show higher affinities than approved therapeutic antibodies. This very often circumvents the need for affinity maturation, accelerating discovery of antibody drug candidates.
Collapse
|
32
|
Toutain CM, Clarke DJ, Leeds JA, Kuhn J, Beckwith J, Holland IB, Jacq A. The transmembrane domain of the DnaJ-like protein DjlA is a dimerisation domain. Mol Genet Genomics 2003; 268:761-70. [PMID: 12655402 DOI: 10.1007/s00438-002-0793-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2002] [Accepted: 12/03/2002] [Indexed: 11/24/2022]
Abstract
DjlA is a bitopic inner membrane protein, which belongs to the DnaJ co-chaperone family in Escherichia coli. Overproduction of DjlA leads to the synthesis of colanic acid, resulting in mucoidy, via the activation of the two-component regulatory system RcsC/B that controls the cps (capsular polysaccharide) operon. This induction requires both the co-chaperone activity of DjlA, in cooperation with DnaK and GrpE, and its unique transmembrane (TM) domain. Here, we show that the TM segment of DjlA acts as a dimerisation domain: when fused to the N-terminal DNA-binding domain of the lambda cI repressor protein, it can substitute for the native C-terminal dimerisation domain of cI, thus generating an active cI repressor. Replacing the TM domain of DjlA by other TM domains, with or without dimerising capacity, revealed that dimerisation is not sufficient for the induction of cps expression, indicating an additional sequence- or structurally specific role for the TM domain. Finally, the conserved glycines present in the TM domain of DjlA are essential for the induction of mucoidy, but not for dimerisation.
Collapse
Affiliation(s)
- C M Toutain
- Institut de Génétique et Microbiologie, UMR CNRS 8621, Bâtiment 400, Université Paris-Sud, 91405 Orsay, France
| | | | | | | | | | | | | |
Collapse
|
33
|
Alba BM, Leeds JA, Onufryk C, Lu CZ, Gross CA. DegS and YaeL participate sequentially in the cleavage of RseA to activate the sigma(E)-dependent extracytoplasmic stress response. Genes Dev 2002; 16:2156-68. [PMID: 12183369 PMCID: PMC186436 DOI: 10.1101/gad.1008902] [Citation(s) in RCA: 282] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
All cells have stress response pathways that maintain homeostasis in each cellular compartment. In the Gram-negative bacterium Escherichia coli, the sigma(E) pathway responds to protein misfolding in the envelope. The stress signal is transduced across the inner membrane to the cytoplasm via the inner membrane protein RseA, the anti-sigma factor that inhibits the transcriptional activity of sigma(E). Stress-induced activation of the pathway requires the regulated proteolysis of RseA. In this report we show that RseA is degraded by sequential proteolytic events controlled by the inner membrane-anchored protease DegS and the membrane-embedded metalloprotease YaeL, an ortholog of mammalian Site-2 protease (S2P). This is consistent with the mechanism of activation of ATF6, the mammalian unfolded protein response transcription factor by Site-1 protease and S2P. Thus, mammalian and bacterial cells employ a conserved proteolytic mechanism to activate membrane-associated transcription factors that initiate intercompartmental cellular stress responses.
Collapse
Affiliation(s)
- Benjamin M Alba
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143, USA
| | | | | | | | | |
Collapse
|
34
|
Smith SM, McCormick PV, Leeds JA, Garrett PB. Constraints of Seed Bank Species Composition and Water Depth for Restoring Vegetation in the Florida Everglades, U.S.A. Restor Ecol 2002. [DOI: 10.1046/j.1526-100x.2002.10115.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
35
|
Smith SM, Newman S, Garrett PB, Leeds JA. Differential effects of surface and peat fire on soil constituents in a degraded wetland of the northern Florida Everglades. J Environ Qual 2001; 30:1998-2005. [PMID: 11790006 DOI: 10.2134/jeq2001.1998] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The effects of surface (aboveground) and peat (belowground) fire on a number of soil constituents were examined within a hydrologically altered marsh in the northern Florida Everglades. Peat fire resulted in losses of total carbon (TC), total nitrogen (TN), and organic phosphorus (Po), while inorganic phosphorus (Pi) and total calcium (TCa) concentrations increased. In addition, peat fire led to a more pronounced vertical gradient in constituent concentrations between upper and lower soil layers. Surface fire also affected soil constituents, but impacts were small relative to peat fire. The effects of physical versus chemical processes during burning were assessed using ratios of constituent to TCa concentrations. This measure indicated that increases in the levels of total phosphorus (TP) in peat-burned areas were due primarily to the physical reduction of soil, while decreases in TN and TC were the result of volatilization. Increases in concentrations of Pi fractions arose from both chemically and physically mediated processes. In an ecological context, the observed soil transformations may encourage the growth of invasive plant species, such as southern narrow-leaved cattail (Typha domingensis Pers.), which exhibits high growth rates in response to increased P availability.
Collapse
Affiliation(s)
- S M Smith
- Everglades Dep., Watershed Research and Planning Division, South Florida Water Management District, West Palm Beach 33406, USA.
| | | | | | | |
Collapse
|
36
|
Leeds JA, Boyd D, Huber DR, Sonoda GK, Luu HT, Engelman DM, Beckwith J. Genetic selection for and molecular dynamic modeling of a protein transmembrane domain multimerization motif from a random Escherichia coli genomic library. J Mol Biol 2001; 313:181-95. [PMID: 11601855 DOI: 10.1006/jmbi.2001.5007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In order to identify new transmembrane helix packing motifs in naturally occurring proteins, we have selected transmembrane domains from a library of random Escherichia coli genomic DNA fragments and screened them for homomultimerization via their abilities to dimerize the bacteriophage lambda cI repressor DNA-binding domain. Sequences were isolated using a modified lambda cI headpiece dimerization assay system, which was shown previously to measure transmembrane helix-helix association in the E. coli inner membrane. Screening resulted in the identification of several novel sequences that appear to mediate helix-helix interactions. One sequence, representing the predicted sixth transmembrane domain (TM6) of the E. coli protein YjiO, was chosen for further analysis. Using site-directed mutagenesis and molecular dynamics, a small set of models for YjiO TM6 multimerization interface interactions were generated. This work demonstrates the utility of combining in vivo genetic tools with computational systems for understanding membrane protein structure and assembly.
Collapse
Affiliation(s)
- J A Leeds
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
Affiliation(s)
- J A Leeds
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | |
Collapse
|
38
|
Abstract
To understand the determinants of membrane protein interactions, we have developed an in vivo genetic assay system for detecting homodimerization of transmembrane (TM) segments from integral membrane proteins. Our approach is to generate gene fusions between potentially dimerizing TM segments and a cytoplasmic DNA-binding protein that lacks its intrinsic dimerization domain. This genetic approach allows us to screen and distinguish among known dimerizing domains and weakly dimerizing mutants, as well as non-dimerizing TM segments. We replaced the bacteriophage lambda cI repressor C-terminal dimerization domain with the human erythrocyte glycophorin A transmembrane segment (GpA TM). GpA TM forms SDS-resistant homodimers in vitro. Expression of this membrane-associated fusion in Escherichia coli conferred the same degree of immunity to lambda cI phages as the wild-type, intact lambda repressor. Single amino acid substitutions that disrupt the GpA TM dimer interface were introduced into the lambda-GpA TM fusion proteins. These mutations dramatically reduced immunity of E. coli to lambda cI, such that the efficiency of plating these phages increased by greater than 10,000-fold over that conferred by the wild-type lambda-GpA TM fusion. Introduction of the putatively non-dimerizing first TM from E. coli MalF into the lambda-TM fusion vector resulted in no immunity to lambda cI phages. Fusion of the homodimeric, periplasmically localized, mature alkaline phosphatase domain to the C terminus of the lambda-TM fusion proteins containing weakly to non-dimerizing TM segments restored immunity to lambda cI phages. Results from this in vivo genetic assay system demonstrate that (1) dimerization of the lambda cI DNA-binding domain can be promoted by dimerizing TM segments, (2) strongly, weakly, and non-dimerizing TM segments can be distinguished on the basis of their ability to confer immunity to lambda cI phages, and (3) introduction of a dimerizing periplasmic domain can provide functionality to lambda-TM fusions containing weakly to non-dimerizing TM segments.
Collapse
Affiliation(s)
- J A Leeds
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
| | | |
Collapse
|
39
|
Leeds JA, Welch RA. Enhancing transcription through the Escherichia coli hemolysin operon, hlyCABD: RfaH and upstream JUMPStart DNA sequences function together via a postinitiation mechanism. J Bacteriol 1997; 179:3519-27. [PMID: 9171395 PMCID: PMC179143 DOI: 10.1128/jb.179.11.3519-3527.1997] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Escherichia coli hlyCABD operons encode the polypeptide component (HlyA) of an extracellular cytolytic toxin as well as proteins required for its acylation (HlyC) and sec-independent secretion (HlyBD). The E. coli protein RfaH is required for wild-type hemolysin expression at the level of hlyCABD transcript elongation (J. A. Leeds and R. A. Welch, J. Bacteriol. 178:1850-1857, 1996). RfaH is also required for the transcription of wild-type levels of mRNA from promoter-distal genes in the rfaQ-K, traY-Z, and rplK-rpoC gene clusters, supporting the role for RfaH in transcriptional elongation. All or portions of a common 39-bp sequence termed JUMPStart are present in the untranslated regions of RfaH-enhanced operons. In this study, we tested the model that the JUMPStart sequence and RfaH are part of the same functional pathway. We examined the effect of JUMPStart deletion mutations within the untranslated leader of a chromosomally derived hlyCABD operon on hly RNA and HlyA protein levels in either wild-type or rfaH null mutant E. coli. We also provide in vivo physical evidence that is consistent with RNA polymerase pausing at the wild-type JUMPStart sequences.
Collapse
Affiliation(s)
- J A Leeds
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison 53706, USA
| | | |
Collapse
|
40
|
Abstract
Escherichia coli hlyCABD operons encode the polypeptide component (Hly A) of an extracellular cytolytic toxin, as well as proteins required for its acylation (HlyC) and sec-independent secretion (HlyBD). Previous reports suggested that the E. coli protein RfaH is required for wild-type hemolysin expression, either by positively activating hly transcript initiation (M. J. A. Bailey, V. Koronakis, T. Schmoll, and C. Hughes, Mol. Microbiol. 6:1003-1012, 1992) or by promoting proper insertion of hemolysin export machinery in the E. coli outer membrane (C. Wandersman and S. Letoffe, Mol. Microbiol. 7:141-150, 1993). RfaH is also required for wild-type levels of mRNA transcribed from promoter-distal genes in the rfaQ-K, traY-Z, and rplK-rpoC gene clusters, suggesting that RfaH is a transcriptional antiterminator. We tested these models by analyzing the effects of rfaH mutations on hlyCABD mRNA synthesis and decay, HlyA protein levels, and hemolytic activity. The model system included a uropathogenic strain of E. coli harboring hlyCABD on the chromosome and E. coli K-12 transformed with the hlyCABD operon on a recombinant plasmid. Our results suggest that RfaH enhances hlyCABD transcript elongation, consistent with the model of RfaH involvement in transcriptional antitermination in E. coli. We also demonstrated that RfaH increases toxin efficacy. Modulation of hemolysin activity may be an indirect effect of RfaH-dependent E. coli outer membrane chemotype, which is consistent with the model of lipopolysaccharide involvement in hemolytic activity.
Collapse
Affiliation(s)
- J A Leeds
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison 53706, USA
| | | |
Collapse
|
41
|
Welch RA, Bauer ME, Kent AD, Leeds JA, Moayeri M, Regassa LB, Swenson DL. Battling against host phagocytes: the wherefore of the RTX family of toxins? Infect Agents Dis 1995; 4:254-72. [PMID: 8665089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The RTX family of bacterial exotoxins is a group of related cytolytic proteins produced by a wide variety of gram-negative human and animal pathogens. While diverse in their associated diseases and in their target cell specificities, there remain several themes common to RTX toxins, including genetic organization, structural and functional features, and effects on target cells. In this review, we summarize and discuss the genetics, regulation, epidemiology, structure/function relationships, and in vivo and in vitro activities of the best characterized RTX toxins, and speculate on their roles in pathogenesis and their use in immunotherapy.
Collapse
Affiliation(s)
- R A Welch
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison Medical School 53706, USA
| | | | | | | | | | | | | |
Collapse
|