Broadly defined, my research interests are in the areas of gene regulation and protein structure-function relationships: (1) How do cells sense and respond to environmental signals at the molecular level, and (2) how are proteins "evolutionarily engineered" to precisely execute their activities in the cell. Both of these fundamental questions are being addressed in the model bacterium Rhodobacter sphaeroides 2.4.1. This organism is able to obtain energy by aerobic and anaerobic respiration and by photosynthesis, and possesses regulatory networks that suitably coordinate gene expression in order to achieve this metabolic flexibility. It also possesses isoenzymes that catalyze the same reaction in the same organism, which allows for a comparative analysis of the relationship between structure and function. To investigate these topics, a combination of genetic and biochemical approaches is employed. Thus, the power of selection is used to identify loci of interest, and molecular biology techniques are used to construct specially designed strains that allow us to direct these selections. To quantitate expression levels, and to compare and contrast biochemical characteristics of gene products of interest both in vivo and in vitro analyses are used. An exciting recent development in these pursuits is the availability of the DNA sequence of the entire genome of R. sphaeroides 2.4.1, making it possible to undertake investigations of a scale and scope that would otherwise not be feasible. Most recently, genome-wide (transcriptome) investigations of gene expression have been undertaken using oligonucleotide array Affymetrix chips. We have also begun studies to investigate the ability of this versatile bacterium to both bioremediate environmental pollutants and concurrently produce commercially valuable products such as hydrogen and bioplastics.
Tsuzuki, M, OV Moskvin, M Kuribayashi, K Sato, S Retamal*, M Abo, J Zeilstra-Ryalls, and M Gomelsky. 2011. Salt stress-induced changes in the transcriptome, compatible solutes, and membrane lipids in the facultatively phototrophic bacterium Rhodobacter sphaeroides. Appl. Environ. Microbiol. 77:7551-7559.
Suwansaard M*, W choorit, JH Zeilstra-Ryalls, and P Prasertsan. 2010. Phototrophic hydrogen production by the newly isolated strain of Rhodopseudomonas palustris TN1. Biotechnology Letters 32: 1667-71.
Suwansaard M*, W Choorit, JH Zeilstra-Ryalls, and P Prasertan. 2009. Isolation of anoxygenic photosynthetic bacteria from Songkhla Lake for use in a teo-staged biohydrogen production process from palm oil mill effluent. Journal of Hydrogen Energy 34: 7523-7529.
Ranson-Olson, B.* and J.H. Zeilstra-Ryalls. 2008. Regulation of the Rhodobacter sphaeroides 2.4.1 hemA gene by PrrA and FnrL. J. Bacteriol. 190: 6769-6778.
Zeilstra-Ryalls, J.H. 2008. Chapter 42. Regulation of the tetrapyrrole biosynthetic pathway. In: The Purple Phototrophic Bacteria. C. Neil Hunter, Fevzi Daldal, Marion C. Thurnauer, and J. Thomas Beattty (eds). Springer. The Netherlands (in press).
Ranson-Olson*, B., D.F. Jones, T.J. Donohue, and J. Zeilstra-Ryalls. 2006. In vitro and in vivo analysis of the role of PrrA in Rhodobacter sphaeroides 2.4.1 hemA gene expression. J. Bacteriol. 188:3208-3218.
Zeilstra-Ryalls, J.H. and K.L. Schornberg*. 2006. Analysis of hemF gene function and expression in Rhodobacter sphaeroides 2.4.1. J. Bacteriol. 188:801-804.
Zeilstra-Ryalls, J.H. and S. Kaplan. 2004. Oxygen intervention in the regulation of gene expression: the photosynthetic bacterial paradigm. Cellular and Molecular Life Sciences 61:417-36.
Fales*, L., L. Kryszak*, and J. Zeilstra-Ryalls. 2002. Analysis of hemA expression in Rhodobacter sphaeroides 2.4.1: in vivo evidence for two promoters that are both regulated by fnrL. Photosynthesis Research 74:143-151.
Mackenzie, C., M. Choudhary, F.W. Larimer, P.F. Predki, S. Stilwagen, J.P. Armitage, R.D. Barber, T.J. Donohue, J.P. Hosler, J.E. Newman, J.P. Shapleigh, R.E. Sockett, J. Zeilstra-Ryalls, and S. Kaplan. 2001. The home stretch, a first analysis of the nearly completed genome of Rhodobacter sphaeroides 2.4.1. Photosynthesis Research 70:19-41.
Fales*, L., L. Kryszak*, and J. Zeilstra-Ryalls. 2001. Control of hemA expression in Rhodobacter sphaeroides 2.4.1: effect of a transposon insertion in hbdA. Journal of Bacteriology 183:1568-1576.
* indicates student authors