Erin R. Murphy

Erin on Maui.

Education

B.A. (Biology), State University of New York at Geneseo, 1997

Ph.D. (Microbiology), State University of New York at Buffalo, 2002

Research Interest

Analysis of RyhB and Iron Regulation in Shigella dysenteriae and Shigella flexneri

Shigella, the causative agent of dysentery, regulates the expression of specific genes in response to the local concentration of iron.  This regulation is largely mediated by Fur (ferric uptake regulator), a global iron-dependent transcriptional repressor.  In Escherichia coli, a regulatory cascade has been identified in which Fur represses the expression of RyhB, a small regulatory RNA.  RyhB in turn represses the expression of genes involved in iron metabolism and storage.  DNA sequencing and database analysis were used to identify ryhB in both S. dysenteriae and S. flexneri.  The nucleic acid sequence of each is nearly identical to that of E. coli ryhB.  To investigate the role of ryhB in iron utilization, virulence and gene expression in S. dysenteriae and S. flexneri deletion strains were generated by the replacement of the ryhB coding region with a chloramphenicol resistance cassette.   Additionally, constructs were engineered to over-express Shigella ryhB.  While the deletion of ryhB does not appear to alter the ability of Shigella to utilize various iron sources for growth, ryhB over-expression does alter the iron utilization pattern of S. dysenteriae.  Neither deletion nor over-expression of ryhB appears to abolish the ability of Shigella to invade and spread within epithelial cells as determined by tissue culture plaque assays.  A detailed analysis of RyhB and its role in pathogenesis and gene regulation of Shigella will provide insights into the iron and RyhB regulons of these enteric pathogens.

Publications/Abstracts-

Murphy, E.R. and S.M. Payne. 2004. Analysis of RyhB and Iron Regulation in Shigella dysenteriae and Shigella flexneri. 104^th ASM General Meeting.

Oglesby A.G., E.R. Murphy, B.E. Reus, J.L. Davies, V.R. Iyer, S.M. Payne.  2003.  Microarray Analysis of Iron-Regulated Gene Expression in Shigella flexneri.  103rd ASM General Meeting.

Murphy, E.R., R.E. Sacco, A. Dickenson, D.J. Metzger, Y. Hu, P.E. Orndorff and T.D. Connell. 2002. “BhuR, a Virulence-Associated Outer Membrane Protein of Bordetella avium, is Required for the Acquisition of Iron from Heme and Hemoproteins. Infection and Immunity. 70:5390-5403.

Kirby, A.E., D.J. Metzger, E.R. Murphy, and T.D. Connell. 2001. “Heme Utilization in Bordetella avium is Regulated by RhuI, a Heme-Responsive Extra-cytoplasmic Function Sigma Factor. Infection and Immunity.” 69:6951-6961.

Murphy, E.R., A. Dickenson, K. Militello, and T.D. Connell. 1999. “Genetic Characterization of Wild-Type and Mutant fur Genes of Bordetella avium.” Infection and Immunity. 67:3160-3165.

EMAIL ADDRESS: ermurphy@mail.utexas.edu