James Riordan

Associate Professor of InstructionCMMB Director of Undergraduate Studies


Office: ISA 3006
Phone: (813) 974-0892


Ph.D. Molecular Biology, New Mexico State University, 2006.

Past RESEARCH Experience

Regulation of virulence and stress fitness in pathogenic E. coli:

Alternative sigma factor N:
Sigma N (encoded by rpoN) is an alternative sigma subunit of the RNA polymerase machinery that confers specificity to transcription initiation under specific growth conditions. We have determined that the deletion of rpoN in E. coli modulate the expression of gene clusters involved in resistance to acid (important for low infectious dose and for transmission), as well as those encoded on a pathogenicity island (the LEE) important for gut colonization (Riordan et al. 2009, Microbiology 156(Pt. 3):719. PubMed); (Mitra et al. 2012, PLoS One. 7(9): e46288 (PMID 23029465) PubMed. Current studies examine the stimuli and mechanisms by which sigma N is activated to control acid resistance and the LEE, and the significance of this control to disease progression.

Rcs phosphorelay:
Rcs is a multi-component phosphorelay system in E. coli which transmits various environmental signals to the transcriptional machinery. We have determined that the Rcs system is required for activation of the locus of enterocyte effacement (LEE) in response to physiologic bicarbonate in the intestine (Morgan et al. 2013, Microbiology 159:2342. PubMed). Adding to this, a reciprocating pathway has been identified by our group in which Rcs and the LEE-encoded regulator GrlA cooperatively repress motility. These observations have led us to hypothesize that Rcs phosphorelay coordinates LEE activation and adherence with LEE-directed repression of motility and dispersion in response to gut stimuli.