title: LPS modification promotes maintenance of Yersinia pestis in fleas.
abstract: Yersinia pestis, the causative agent of plague, can be transmitted by fleas by two different mechanisms: by early-phase transmission (EPT), which occurs shortly after flea infection, or by blocked fleas following long-term infection. Efficient flea-borne transmission is predicated upon the ability of Y. pestis to be maintained within the flea. Signature-tagged mutagenesis (STM) was used to identify genes required for Y. pestis maintenance in a genuine plague vector, Xenopsylla cheopis. The STM screen identified seven mutants that displayed markedly reduced fitness in fleas after 4 days, the time during which EPT occurs. Two of the mutants contained insertions in genes encoding glucose 1-phosphate uridylyltransferase (galU) and UDP-4-amino-4-deoxy-l-arabinose-oxoglutarate aminotransferase (arnB), which are involved in the modification of lipid A with 4-amino-4-deoxy-l-arabinose (Ara4N) and resistance to cationic antimicrobial peptides (CAMPs). These Y. pestis mutants were more susceptible to the CAMPs cecropin A and polymyxin B, and produced lipid A lacking Ara4N modifications. Surprisingly, an in-frame deletion of arnB retained modest levels of CAMP resistance and Ara4N modification, indicating the presence of compensatory factors. It was determined that WecE, an aminotransferase involved in biosynthesis of enterobacterial common antigen, plays a novel role in Y. pestis Ara4N modification by partially offsetting the loss of arnB. These results indicated that mechanisms of Ara4N modification of lipid A are more complex than previously thought, and these modifications, as well as several factors yet to be elucidated, play an important role in early survival and transmission of Y. pestis in the flea vector.
authors.affiliation: University of Utah Department of Pathology, 2100 JMRB, 15 North Medical Drive East, Salt Lake City, UT 84132, USA.
authors.forename: Kari L
authors.initials: KL
authors.lastname: Aoyagi
authors.affiliation: University of Utah Department of Pathology, 2100 JMRB, 15 North Medical Drive East, Salt Lake City, UT 84132, USA.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Brooks
authors.affiliation: Division of Vector-Borne Diseases, Bacterial Diseases Branch, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Bearden
authors.affiliation: Division of Vector-Borne Diseases, Bacterial Diseases Branch, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Montenieri
authors.affiliation: Division of Vector-Borne Diseases, Bacterial Diseases Branch, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, USA.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Gage
authors.affiliation: University of Utah Department of Pathology, 2100 JMRB, 15 North Medical Drive East, Salt Lake City, UT 84132, USA ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA mark.fisher@path.utah.edu.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Fisher
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007303:Insect Vectors / Q000382:microbiology*; D008050:Lipid A / Q000378:metabolism*; D050296:Microbial Viability; D010930:Plague / Q000382:microbiology* / Q000635:transmission; D051381:Rats; D017207:Rats, Sprague-Dawley; D005423:Siphonaptera / Q000382:microbiology*; D015010:Yersinia pestis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008050:Lipid A