VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

[4] Yue, D. et al (2008): Fluorescence in situ hybridization (FISH) analysis of the interactionsbetween honeybee larvae and Panibacillus larvae, the causative agent of American foulbrood ofhoneybees (Apis mellifera). Environ. Microbiol. 10, 1612-1620.MPP048Staphylococcus saprophyticus is able to adapt toutilization of D-serine as the carbon and energy sourceM. Korte*, L. Marlinghaus, S. Neumann, F. Szabados, S. GatermannDepartment of Medical Microbiology, Ruhr-University, Bochum, GermanyS. saprophyticus is the only species of the staphylococci that is typicallyuropathogenic. Several virulence factors have already been identified, but ithas been suggested that also certain metabolic activities may contribute tovirulence. The genome of S. saprophyticus is the only one of all sequencedstaphylococci which possesses a D-serine deaminase, an enzyme whichconverts D-serine to pyruvate and ammonia. Interestingly, this enzyme isalso present in other uropathogenic bacteria like E. coli (UPEC). The aminoacid D-serine is present in relatively high concentrations in human urine andis toxic or bacteriostatic to several non-uropathogenic bacteria. Therefore theuncommon ability to degrade D-serine may play an important role for thevirulence of uropathogens. In addition the presence of D-serine may be usedas a cue by uropathogens for the presence in the urinary tract. To analyze themetabolism and to understand the significance of D-serine catabolism of S.saprophyticus for virulence, we developed a chemically defined medium. Bysystematically adding and removing components from this medium, wecould show that S. saprophyticus is able to use D-serine as the sole carbonand energy source. Remarkably, the lag time is much longer when D-serineis used compared to that when glucose is used as energy source. When S.saprophyticus is once adapted to D-serine, it grows immediately without anextended lag phase when it is inoculated into fresh media with D-serine assole carbon source. Moreover, when S. saprophyticus is adapted to D-serine,it grows slower with glucose. These results show that S. saprophyticus isable to change its metabolism in the presence of D-serine and to adapt to thisnutrient. That leads us to the hypothesis that a similar adaptation couldhappen within the urinary tract. To get more insights into the kind ofadaptation, we conducted 2D-gelelectrophoresis and analyzed the proteinpatterns of S. saprophyticus adapted to glucose and adapted to D-serine.MPP049Zwitterionic cell wall polymers with immune modulatoryfunction - important players in CA-MRSApathogenicity?S. Wanner*, C. Weidenmaier, S. Baur, M. Rautenberg, L. KullInstitute of Microbiology and Infection Medicine (IMIT), MedicalMicrobiology, Eberhard-Karls-University, Tübingen, GermanyStaphylococcus aureus can cause a large variety of infections but skin andsoft-tissue infections are the most common type. Recently, communityacquiredmethicillin-resistant (CA-MRSA) isolates which often carry thegene for the Panton-Valentine leukocidin (PVL) emerged as the major causeof severe skin and soft-tissue infections (SSTIs) caused by S. aureus in theUSA. The pathogenic potential of CA-MRSA strains seems to depend on anarray of different virulence factors, however the relative activity of thesefactors is still unclear. We recently demonstrated that the cell wall polymerWTA (cell wall teichoic acid) of S. aureus is a major modulator of abscessformation. The immune modulatory activity of WTA depends on itszwitterionic nature and the ability to activate CD4 T cells after presentationon MHC II molecules in antigen presenting cells. In turn the zwitterionicWTA activated T cells influence abscess formation by regulating the localcytokine milieu. Interestingly, we find that highly pathogenic CA-MRSAstrains exhibit an elevated WTA amount in their cell walls. Purified proteinfreecell wall fractions from CA-MRSA induce T cell proliferation andcytokine production more efficiently than cell wall from non CA-MRSA. Inaddition we could demonstrate that cell wall fractions of CA-MRSA strainsare more active in skin abscess formation. Thus, upregulation of WTAbiosynthesis in CA-MRSA contributes to pathogenic potential of CA-MRSA. The major focus of this project is to understand how zwitterionicWTA of CA-MRSA shapes the pathogenic potential and what molecularevents are involved on the host side.MPP050Why does Staphylococcus aureus decorate its wall teichoicacid with N-acetylglucosamine?G. Xia* 1 , L. Maier 1 , P. Sanchez-Carballo 2 , O. Holst 2 , A. Peschel 11 Institute of Microbiology and Infection Medicine, Eberhard-Karls-University, Tübingen, Germany2 Research Center Borstel, Structural Biochemistry, Borstel, GermanyWall teichoic acid (WTA) glycopolymers are major constituents of cellenvelopes in Staphylococcus aureus and related Gram-positive bacteria withimportant roles in cell wall maintenance, susceptibility to antimicrobialmolecules, biofilm formation, and host interaction. Most S. aureus strainsexpress poly-ribitolphosphate (Rbo-P) WTA substituted with d-alanine andN-acetylglucosamine (GlcNAc). WTA sugar modifications are highlyvariable and have been implicated in bacterial phage susceptibility andimmunogenicity but the pathway and enzymes of staphylococcal WTAglycosylation have remained unknown.Revisiting the structure of S. aureus RN4220 WTA by NMR analysisrevealed the presence of canonical Rbo-P WTA bearing only a-linkedGlcNAc substituents. A RN4220 transposon mutant resistant to WTAdependentphages was identified and shown to produce altered WTA, whichexhibited faster electrophoretic migration and lacked completely the WTAa-GlcNAc residues. Disruption of a gene of previously unknown function,renamed tarM, was responsible for this phenotype. Recombinant TarM wascapable of glycosylating WTA in vitro in a UDP-GlcNAc dependent mannerthereby confirming its WTA GlcNAc transferase activity. Deletion of thelast seven amino acids from the C-terminus abolished the activity of TarM.tarM-related genes were found in the genomes of several WTA-producingbacteria suggesting that TarM-mediated WTA glycosylation is a generalpathway in Gram-positive bacteria.Our study represents a basis for dissecting the biosynthesis and function ofglycosylated WTA in S. aureus and other bacteria.MPP051Construction and characterization of three fbl knockoutmutants of Staphylococcus lugdunensisL. Marlinghaus*, F. Szabados, M. Korte, S. Neumann, S. GatermannDepartment of Medical Microbiologie, Ruhr-University, Bochum, GermanyStaphylococcus lugdunensis is a commensal and integral part of the normalskin flora but also a important pathogen that causes several seriousinfections similar to those caused by Staphylococcus aureus, likeendocarditis, sepsis, skin and soft tissue infections. In contrast to S. aureus,data on pathogenicity factors of S. lugdunensis is scarce due to fact that anisogenic genetic manipulation of S. lugdunensis has not yet been described.We present the first transformation and directed isogenic geneticmanipulation of S. lugdunensis described so far. Knockout mutants of the fblgene were constructed from three different strains of S. lugdunensis to showthat at least in these strains fibrinogen binding is exclusively mediated byFbl. Only 29 out of 104 (27.9 %) clinical isolates of S. lugdunensis bound tofibrinogen although the prevalence of the fbl gene was very high (100 %).Strains that showed binding to immobilized fibrinogen also induce aclumping in the short coagulase test. In contrast to their wildtypes isogenicS. lugdunensis mutants lacking the fbl gene neither bind to fibrinogen norclump in the short coagulase test.MPP052Mutants of Xanthomonas campestris pv. vesicatoriadevoid of aconitase B exhibit reduced pathogenicity onpepper leavesJ. Kirchberg* 1 , B. Thiemer 1 , D. Büttner 2 , G. Sawers 11 Institute for Biology/Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany2 Institute for Biology/Genetics, Martin-Luther-University Halle-Wittenberg,Halle, GermanyBacterial class A and B aconitases (Acn) are iron-sulfur (FeS) proteins thatdiffer in the organisation of their respective domain structures [1]. AcnA andAcnB each can have two different functions depending on the cellular ironlevel. If iron is plentiful Acn possesses a labile [4Fe-4S] cluster and isfunctional in the TCA cycle. If, however, iron is limiting then the enzymeloses its [4Fe-4S] cluster and adopts a post-transcriptional regulatoryfunction as an iron regulatory protein (IRP). In many bacteria the apo-formspektrum | Tagungsband 2011