title: A transposon site hybridization screen identifies galU and wecBC as important for survival of Yersinia pestis in murine macrophages.
abstract: Yersinia pestis is able to survive and replicate within murine macrophages. However, the mechanism by which Y. pestis promotes its intracellular survival is not well understood. To identify genes that are important for Y. pestis survival in macrophages, a library comprised of ∼31,500 Y. pestis KIM6+ transposon insertion mutants (input pool) was subjected to negative selection in primary murine macrophages. Genes underrepresented in the output pool of surviving bacteria were identified by transposon site hybridization to DNA oligonucleotide microarrays. The screen identified several genes known to be important for survival of Y. pestis in macrophages, including phoPQ and members of the PhoPQ regulon (e.g., pmrF). In addition, genes predicated to encode a glucose-1-phosphate uridylyltransferase (galU), a UDP-N-acetylglucosamine 2-epimerase (wecB) and a UDP-N-acetyl-d-mannosamine dehydrogenase (wecC) were identified in the screen. Viable-count assays demonstrated that a KIM6+ galU mutant and a KIM6+ wecBC mutant were defective for survival in murine macrophages. The galU mutant was studied further because of its strong phenotype. The KIM6+ galU mutant exhibited increased susceptibility to the antimicrobial peptides polymyxin B and cathelicidin-related antimicrobial peptide (CRAMP). Polyacrylamide gel electrophoresis demonstrated that the lipooligosaccharide (LOS) of the galU mutant migrated faster than the LOS of the parent KIM6+, suggesting the core was truncated. In addition, the analysis of LOS isolated from the galU mutant by mass spectrometry showed that aminoarabinose modification of lipid A is absent. Therefore, addition of aminoarabinose to lipid A and complete LOS core (galU), as well as enterobacterial common antigen (wecB and wecC), is important for survival of Y. pestis in macrophages.
authors.affiliation: Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Klein
authors.forename: Hana S
authors.initials: HS
authors.lastname: Fukuto
authors.forename: Mark
authors.initials: M
authors.lastname: Pelletier
authors.forename: Galina
authors.initials: G
authors.lastname: Romanov
authors.forename: Jens P
authors.initials: JP
authors.lastname: Grabenstein
authors.forename: Lance E
authors.initials: LE
authors.lastname: Palmer
authors.forename: Robert
authors.initials: R
authors.lastname: Ernst
authors.forename: James B
authors.initials: JB
authors.lastname: Bliska
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002237:Carbohydrate Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D002238:Carbohydrate Epimerases / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D050296:Microbial Viability; D016254:Mutagenesis, Insertional; D010930:Plague / Q000382:microbiology*; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000235:genetics / Q000378:metabolism*; D015010:Yersinia pestis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D002237:Carbohydrate Dehydrogenases; C023228:UDP-N-acetylmannosamine dehydrogenase; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; D002238:Carbohydrate Epimerases; C100033:UDP acetylglucosamine-2-epimerase