title: Mechanisms and fitness costs of resistance to antimicrobial peptides LL-37, CNY100HL and wheat germ histones.
abstract: Antimicrobial peptides (AMPs) represent a potential new class of antimicrobial drugs with potent and broad-spectrum activities. However, knowledge about the mechanisms and rates of resistance development to AMPs and the resulting effects on fitness and cross-resistance is limited. We isolated antimicrobial peptide (AMP) resistant Salmonella typhimurium LT2 mutants by serially passaging several independent bacterial lineages in progressively increasing concentrations of LL-37, CNY100HL and Wheat Germ Histones. Significant AMP resistance developed in 15/18 independent bacterial lineages. Resistance mutations were identified by whole genome sequencing in two-component signal transduction systems (pmrB and phoP) as well as in the LPS core biosynthesis pathway (waaY, also designated rfaY). In most cases, resistance was associated with a reduced fitness, observed as a decreased growth rate, which was dependent on growth conditions and mutation type. Importantly, mutations in waaY decreased bacterial susceptibility to all tested AMPs and the mutant outcompeted the wild type parental strain at AMP concentrations below the MIC for the wild type. Our data suggests that resistance to antimicrobial peptides can develop rapidly through mechanisms that confer cross-resistance to several AMPs. Importantly, AMP-resistant mutants can have a competitive advantage over the wild type strain at AMP concentrations similar to those found near human epithelial cells. These results suggest that resistant mutants could both be selected de novo and maintained by exposure to our own natural repertoire of defence molecules.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
authors.forename: Hava
authors.initials: H
authors.lastname: Lofton
authors.forename: Maria
authors.initials: M
authors.lastname: Pränting
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Thulin
authors.forename: Dan I
authors.initials: DI
authors.lastname: Andersson
mesh_terms: D000249:Adenosine Monophosphate / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000378:metabolism; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D006657:Histones; D008070:Lipopolysaccharides; D000249:Adenosine Monophosphate; D054804:Cathelicidins
references.citation: J Biol Chem. 2000 Oct 20;275(42):32940-9
references.pmid: 10903325
references.citation: J Bacteriol. 1997 Nov;179(21):6688-91
references.pmid: 9352917
references.citation: J Biol Chem. 1998 Oct 9;273(41):26310-6
references.pmid: 9756860
references.citation: Antimicrob Agents Chemother. 2009 Dec;53(12):5150-4
references.pmid: 19752280
references.citation: J Bacteriol. 1996 Nov;178(21):6369-73
references.pmid: 8892844
references.citation: Biochemistry. 2008 Sep 2;47(35):9057-70
references.pmid: 18690701
references.citation: Biochim Biophys Acta. 1976 Nov 12;454(1):154-71
references.pmid: 990318
references.citation: Biol Lett. 2012 Jun 23;8(3):416-8
references.pmid: 22279153
references.citation: Nature. 2002 Jan 24;415(6870):389-95
references.pmid: 11807545
references.citation: J Antimicrob Chemother. 2007 Apr;59(4):786-90
references.pmid: 17307769
references.citation: Proc Natl Acad Sci U S A. 1987 Aug;84(15):5449-53
references.pmid: 3299384
references.citation: Trends Microbiol. 2008 Jun;16(6):284-90
references.pmid: 18467098
references.citation: J Biol Chem. 2001 Nov 16;276(46):43111-21
references.pmid: 11535603
references.citation: Infect Immun. 1990 Nov;58(11):3706-10
references.pmid: 2172166
references.citation: Diagn Microbiol Infect Dis. 1999 Sep;35(1):45-53
references.pmid: 10529881
references.citation: J Bacteriol. 2003 Mar;185(5):1659-71
references.pmid: 12591884
references.citation: Antimicrob Agents Chemother. 1998 Sep;42(9):2206-14
references.pmid: 9736536
references.citation: Mol Microbiol. 2005 Aug;57(4):900-12
references.pmid: 16091033
references.citation: J Gen Microbiol. 1980 Sep;120(1):173-81
references.pmid: 7012273
references.citation: Nat Rev Microbiol. 2010 Apr;8(4):260-71
references.pmid: 20208551
references.citation: Cell. 1998 Oct 16;95(2):189-98
references.pmid: 9790526
references.citation: Infect Immun. 2004 Sep;72(9):4973-84
references.pmid: 15321989
references.citation: Microbiology (Reading). 2002 Aug;148(Pt 8):2361-2369
references.pmid: 12177330
references.citation: Infect Immun. 2000 Nov;68(11):6139-46
references.pmid: 11035717
references.citation: Nat Med. 2006 Jun;12(6):636-41
references.pmid: 16751768
references.citation: Microbes Infect. 2001 Nov-Dec;3(14-15):1327-34
references.pmid: 11755422
references.citation: Mol Microbiol. 2006 Aug;61(3):645-54
references.pmid: 16803591
references.citation: Mol Microbiol. 2006 May;60(4):820-7
references.pmid: 16677295
references.citation: J Bacteriol. 1996 Dec;178(23):6857-64
references.pmid: 8955307
references.citation: Antimicrob Agents Chemother. 2009 Oct;53(10):4345-51
references.pmid: 19635950
references.citation: Infect Disord Drug Targets. 2008 Sep;8(3):195-205
references.pmid: 18782037
references.citation: Microbiology (Reading). 2003 Jun;149(Pt 6):1367-1375
references.pmid: 12777478
references.citation: J Infect Dis. 1998 Apr;177(4):1023-9
references.pmid: 9534977
references.citation: J Endotoxin Res. 2005;11(3):133-44
references.pmid: 15949142
references.citation: Proc Biol Sci. 2006 Jan 22;273(1583):251-6
references.pmid: 16555795
references.citation: Infect Immun. 2000 Jun;68(6):3758-62
references.pmid: 10816543
references.citation: EMBO J. 2000 Oct 2;19(19):5071-80
references.pmid: 11013210
references.citation: J Genet. 1949 Dec;49(3):264-85
references.pmid: 24536673
references.citation: PLoS One. 2011;6(8):e23100
references.pmid: 21853073
references.citation: Mol Microbiol. 1998 Mar;27(6):1171-82
references.pmid: 9570402
references.citation: Arch Oral Biol. 2012 Jul;57(7):865-9
references.pmid: 22336091
references.citation: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
references.pmid: 10829079
references.citation: Eur J Biochem. 1996 Jun 1;238(2):325-32
references.pmid: 8681941
references.citation: Gene. 1995 May 26;158(1):9-14
references.pmid: 7789817
references.citation: Biochem Biophys Res Commun. 2003 Dec 26;312(4):1139-46
references.pmid: 14651991
references.citation: Mol Microbiol. 2010 Mar;75(5):1078-89
references.pmid: 20088865
references.citation: Annu Rev Biochem. 2002;71:635-700
references.pmid: 12045108
references.citation: Nat Rev Microbiol. 2006 Apr;4(4):295-305
references.pmid: 16541137
references.citation: Infect Immun. 2000 Aug;68(8):4485-91
references.pmid: 10899846
references.citation: J Endotoxin Res. 2001;7(1):57-62
references.pmid: 11521084
references.citation: J Bacteriol. 1993 Jul;175(13):4154-64
references.pmid: 8391535
references.citation: PLoS Pathog. 2011 Jul;7(7):e1002158
references.pmid: 21811410
references.citation: Nat Biotechnol. 2006 Dec;24(12):1551-7
references.pmid: 17160061
references.citation: J Bacteriol. 2001 Mar;183(6):1835-42
references.pmid: 11222580
references.citation: Infect Immun. 1998 Mar;66(3):1225-32
references.pmid: 9488417
references.citation: Eur J Biochem. 1989 Nov 20;185(3):541-6
references.pmid: 2686988
references.citation: Annu Rev Biochem. 2007;76:295-329
references.pmid: 17362200
references.citation: Proc Natl Acad Sci U S A. 1989 Jul;86(13):5054-8
references.pmid: 2544889
references.citation: J Immunol Methods. 1997 Aug 7;206(1-2):53-9
references.pmid: 9328568