title: Zif, the zoocin A immunity factor, is a FemABX-like immunity protein with a novel mode of action.
abstract: Producer cell immunity to the streptococcolytic enzyme zoocin A, which is a D-alanyl-L-alanine endopeptidase, is due to Zif, the zoocin A immunity factor. Zif has high degrees of similarity to MurM and MurN (members of the FemABX family of proteins), which are responsible for the addition of amino acids to cross bridges during peptidoglycan synthesis in streptococci. In this study, purified peptidoglycans from strains with and without zif were compared to determine how Zif modifies the peptidoglycan layer to cause resistance to zoocin A. The peptidoglycan from each strain was hydrolyzed using the streptococcolytic phage lysin B30, and the resulting muropeptides were separated by reverse-phase high-pressure liquid chromatography, labeled with 4-sulfophenyl isothiocyanate, and analyzed by tandem mass spectrometry in the negative-ion mode. It was determined that Zif alters the peptidoglycan by increasing the proportion of cross bridges containing three L-alanines instead of two. This modification decreased binding of the recombinant target recognition domain of zoocin A to peptidoglycan. Zif-modified peptidoglycan also was less susceptible to hydrolysis by the recombinant catalytic domain of zoocin A. Thus, Zif is a novel FemABX-like immunity factor because it provides resistance to a bacteriolytic endopeptidase by lengthening the peptidoglycan cross bridge rather than by causing an amino acid substitution.
authors.affiliation: Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487-0334, USA.
authors.forename: Shaw R
authors.initials: SR
authors.lastname: Gargis
authors.forename: Amy S
authors.initials: AS
authors.lastname: Gargis
authors.forename: Harry E
authors.initials: HE
authors.lastname: Heath
authors.forename: Lucie S
authors.initials: LS
authors.lastname: Heath
authors.forename: Paul A
authors.initials: PA
authors.lastname: LeBlanc
authors.forename: Maria M
authors.initials: MM
authors.lastname: Senn
authors.forename: Brigitte
authors.initials: B
authors.lastname: Berger-Bächi
authors.forename: Robin S
authors.initials: RS
authors.lastname: Simmonds
authors.forename: Gary L
authors.initials: GL
authors.lastname: Sloan
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D002473:Cell Wall / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D024881:Drug Resistance, Bacterial; D009088:Mucoproteins / Q000378:metabolism; D010457:Peptidoglycan / Q000737:chemistry / Q000302:isolation & purification; D018502:Streptococcus equi / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D009088:Mucoproteins; D010457:Peptidoglycan; D014764:Viral Proteins; C106076:ZooA protein, Streptococcus equi; C010393:lysin, gastropoda
references.citation: EMBO J. 1996 Sep 16;15(18):4789-97
references.pmid: 8890152
references.citation: Appl Environ Microbiol. 2009 Jan;75(1):72-7
references.pmid: 18978086
references.citation: Proc Natl Acad Sci U S A. 1998 May 12;95(10):5752-6
references.pmid: 9576956
references.citation: Proc Natl Acad Sci U S A. 2000 Apr 25;97(9):4891-6
references.pmid: 10759563
references.citation: Biomed Mass Spectrom. 1984 Nov;11(11):601
references.pmid: 6525415
references.citation: J Mass Spectrom. 2003 Apr;38(4):373-7
references.pmid: 12717748
references.citation: Drug Resist Updat. 1998;1(5):325-35
references.pmid: 17092813
references.citation: J Biol Chem. 2006 Jan 6;281(1):549-58
references.pmid: 16257954
references.citation: FEMS Microbiol Lett. 2004 Jul 15;236(2):205-11
references.pmid: 15251198
references.citation: Appl Environ Microbiol. 2001 Sep;67(9):3888-96
references.pmid: 11525982
references.citation: J Bacteriol. 2006 Apr;188(7):2463-72
references.pmid: 16547033
references.citation: FEMS Microbiol Lett. 1998 Jun 1;163(1):73-7
references.pmid: 9631548
references.citation: Appl Environ Microbiol. 2006 Oct;72(10):6825-8
references.pmid: 17021237
references.citation: Amino Acids. 2004 Dec;27(3-4):231-47
references.pmid: 15503232
references.citation: Rapid Commun Mass Spectrom. 2004;18(2):191-8
references.pmid: 14745769
references.citation: FEMS Microbiol Lett. 2007 May;270(1):155-61
references.pmid: 17319876
references.citation: FEMS Microbiol Lett. 2002 Sep 24;215(1):133-8
references.pmid: 12393213
references.citation: FEMS Microbiol Lett. 2000 Jul 1;188(1):81-5
references.pmid: 10867238
references.citation: J Bacteriol. 1997 Jul;179(13):4311-8
references.pmid: 9209049
references.citation: FEMS Microbiol Lett. 2003 Nov 7;228(1):115-9
references.pmid: 14612246
references.citation: Appl Environ Microbiol. 1995 Apr;61(4):1475-9
references.pmid: 7747966
references.citation: Microbiology (Reading). 2003 Oct;149(Pt 10):2733-2738
references.pmid: 14523106
references.citation: Anal Biochem. 1989 Apr;178(1):17-21
references.pmid: 2729569
references.citation: Microbiology (Reading). 2004 Jul;150(Pt 7):2079-2087
references.pmid: 15256551
references.citation: FEMS Microbiol Lett. 2005 Aug 15;249(2):227-31
references.pmid: 16006076