Matt and Jonah to present at Student Seminar on Thursday (26.August) at noon in 2-501 BSB
Background for Matt’s talk
Francisella tularensis Infects and Grows in Small Airway Epithelial Cells: a new target in early infections.
Francisella tularensis is a gram negative facultative intracellular pathogen and is the causative agent of tularemia. Though tularemia is not a common disease, its low infective dose and high mortality rate for untreated infections has classified F. tularensis as a class A select agent that could be utilized as a bioterrorism weapon. Our lab studies F. tularensis by using various genetic tools to study many of the unique traits of the pathogen. I will be discussing recent work, which demonstrates that small airway epithelial cells can be infected by F. tularensis. These cells may play an initial role in an infection as they are likely to be the first cells that F. tularensis comes in contact with in a pneumonic infection. This work adds to the understanding of the route of infection and sets up an important model for studying early infection.
Background for Jonah’s talk
Myxococcus xanthus is a gram-negative soil bacterium that has a complex life cycle. Under starvation conditions, cells aggregate to form spore-containing fruiting bodies which persist until nutrients or suitable bacterial prey become available leading to germination. M. xanthus employs greater than 120 two-component systems, including eight chemosensory signaling pathways in order to regulate its complex developmental program as well as aspects of gene expression, predation, and even carotenoid production. Chemosensory pathways are specialized chemotaxis-like two component systems that enable the cell to respond appropriately to its environment. This occurs through a sensor domain that propagates the signal via a conformational change leading to the phosphorylation of a sensor kinase. The phosphoryl group is transferred to a response regulator, which will prompt the appropriate response.
My research focuses on the genetic characterization of two laboratory strains of M. xanthus, DZ2 and DK1622. A genome wide comparison of the two strains revealed a number of small nucleotide polymorphisms (SNPs). We thus wish to elucidate the physiological impact of these sequence differences in the two strains. The majority of these SNPs occur in annotated genes of unknown function, hypothetical genes and phage genes clustered in approximately 60kb. However, four SNPs occur in three previously characterized genes yielding significant amino acid substitutions. Two SNPs are in frzE, the kinase for the Frz system, which regulates reversal frequency, vegetative swarming, and directed swarming during development. A third SNP occurs in epsK, within a exopolysaccharide (EPS) biosynthesis gene cluster. EPS is required for M. xanthus motility, fruiting body development and cell-cell adhesion. The fourth SNP occurs in a gene encoding a scaffolding protein within a chemosensory system involved in pilus-based motility. We hypothesize that one or more of these SNPs is the cause of the phenotypic differences seen between DZ2 and DK1622 and the objective is to test this hypothesis through genetic manipulation of the two strains to mimic each other.