Graduate Faculty Directory
James Johnson
Department of Biological Sciences
Education
- BS (Auburn)
- PhD (Duke)
Faculty Appointments
Associate Professor of Biology
Research Interest
Molecular mechanisms regulating gene expression and gene product function
Analysis of protein factors and DNA structures which regulate gene activity in Escherichia Coli K12 and Staphylococcus aureus
Microbial sulfur matabolism
Synopsis
My primary research objective is to involve both myself and my associates in studies of the molecular mechanisms regulating gene expression and gene product function. My research projects include examination of the following aspects of molecular biology and microbial genetics:
1. Mutational analyses of genes, or regulatory regions
2. Cloning and sequencing of genes and regulatory regions
3. Studies of the physical structures of these isolated DNA sequences
4. Site directed and transposon mutagenesis of gene encoding nucleic acid sequences
5. Studies of protein effector nucleic acid interactions using E. coli K 12 met regulon genes and gene products as models
6. Analysis of complex transcription patterns (Single gene/multiple promoter systems)
7. Analyses of the in vitro/in vivo protein expression of these DNA sequences
Currently, we are analyzing sulfur metabolism in the Gram positive pathogen Staphylococcus (S.) aureus, and met regulon gene activity in Gram positive and negative bacteria. Our studies of the Staphylococcal system are progressing with regard to definition of nutritional sulfur sources and analysis of the pathways of glutathione and cystine degradation. We are currently investigating two aspects of these pathways. First we are screening mutagenized S. aureus cultures for glutathione auxotrophs. Specific focus of this project is on glutathione auxotrophs due to deficiency in the enzyme Á-glutamyltranspeptidase. Second we
are investigating the genetic identity of an oxido-reductase enzyme system involved in cystine reduction and catabolism by S. aureus.
Publications & Presentations
Collier, C.D. and J.R. Johnson (1990). The metJ193 allele contains a point mutation which alters the hydrophobic pocket responsible for in vitro binding of S adenosylmethionine: Effects upon cell growth and induction of met regulon expression. J. Bacteriol. 172:3918 3924.
- Bala, G.A., C.D. Collier, M.R. Emmett and J.R. Johnson. (1989). Characterization of two mutant metJ proteins with reduced, temperature dependent capacity to control E. coli K 12 met regulon elements. J. Bacteriol. 171:4095 4099.
- Cook, J. and J. R. Johnson. 2006. Isolation and Analysis of Putative Glutathione Auxotrophs of Staphylococcus aureus. Presented at the USIP Scholarly Day Symposia.
- Costleigh, J. R. and J. R. Johnson. 2004. A Biochemical Assay for an Unidentified Oxidoreductase of Staphylococcus Aureus that is able to Reduce The Disulfide Linkage in Cystine. Presented at the USIP Scholarly Day Symposia.
Contact Information
Office:
Science and Technology Center
Room # 273
Box # 38
Phone: 215.596.8521
Email: j.johnso@usp.edu
