Kranz

Gene regulatory studies. As models for gene regulation and transport processes, microbial systems offer distinct advantages over other organisms. These advantages include fast growth rates and versatile genetics and selection techniques. Photosynthetic microorganisms possess the ability to adapt metabolically to a wide range of growth conditions in nature. This capacity to convert from one mode to another is facilitated by complex regulatory systems which respond to changes in their environment. Our research is directed towards understanding these capabilities of photosynthetic bacteria, with particular emphasis on the genes for nitrogen fixation. We have obtained mutants in and have cloned regulatory genes, both negative and positive activators, that respond to oxygen and nitrogen availability. Recently, the nitrogen-sensing kinase cascade has been purified and reconstituted with purified RNA polymerase. A third type of bacterial transcription activation system was discovered (model).

Biogenesis of extracellular components. A second project in the lab concerns the study of cytochrome c biogenesis in photosynthetic bacteria. We have isolated bacterial mutants and genes involved in this assembly process, which occurs outside the cytoplasmic membrane. The model we have developed for this process includes an ATP-dependent heme export system homologous to membrane translocators like the cystic fibrosis protein. Other components that are predicted to function as periplasmic heme and apocytochrome chaperones or thioredox proteins are under investigation.

Bioenergenics of pathogens. A recent interest in the lab concerns the bioenergetics and cytochrome c biogenesis requirements of selected human pathogens. By genomic and gentic analysis we determine which pathways for biogenesis and energ y conversion are necessary for pathogenesis. This area represents a relatively unexplored aspect of microbial pathogenesis.

Biodegradable polymers. We are investigating the abilities of genetically engineered photosynthetic organisms to overproduce unique polyesters (plastics). These polyesters, called polyhydroxyalkanoates (PHAs), are completely biodegradable and require only three genes for their production. We have cloned and characterized these three genes (phaABC) from photosynthetic bacteria. Our studies involve basic and applied problems in this field.

Bowman, W.C. and R. G. Kranz. A bacterial ATP-dependent, enhancer-binding protein that activates the housekeeping RNA polymerase. Genes & Development. In press, (1998).

Kranz, R.G., R. Lill, B. Goldman, G. Bonnard, and S. Merchant. Molecular mechanisms of cytochromes c biogenesis: three distinct systems. Mol. Microbiol. In press, (1998).(Abstract)

Goldman, B.S., D. Beck, E.M. Monika, and R.G. Kranz. Transmembrane heme delivery systems. Proc. Natl. Acad. Sci. USA 95:5003-5008, (1998). (Abstract)

Goldman, B.S. and R.G. Kranz. Evolution and horizontal transfer of an entire biosynthetic pathway for cytochrome c biogenesis: Helicobacter, Deinococcus, Archae, and more. Mol. Microbiol. 27: 871-873, (1998).

Cullen, P.J., W.C. Bowman, S.C. Reilly, D. Foster-Hartnett, and R.G. Kranz. Translational activation by an NtrC enhancer-binding protein. J. Mol. Biol. 278: 903-914, (1998). (Abstract)

Monika, E.M., B.S. Goldman, D.L. Beckman, and R.G. Kranz. 1997. A thioreduction pathway tethered to the membrane for periplasmic cytochromes c biogenesis; in vitro and in vivo studies. J. Mol. Biol. 271: 679-692, (1997). (Abstract)

Gabbert, K.K., B.S. Goldman, and R.G. Kranz. Differential levels of specific cytochrome c biogenesis proteins in response to oxygen: analysis of the ccl operon in Rhodobacter capsulatus. J. Bacteriol.179: 5422-5428, (1997).(Abstract)

Cullen, P.J., C.K. Kaufman, W.C. Bowman, and R.G. Kranz. Characterization of the Rhodobacter capsulatus housekeeping RNA polymerase; in vitro transcription of photosynthesis and other genes. J. Biol. Chem. 272:27266-27273, (1997).(Abstract)

Goldman, B.S., Sherman, D.A., and R.G. Kranz. Comparison of the bacterial HelA protein to the F508 region of the cystic fibrosis transmembrane regulator. J. Bacteriol. 179:7869-7871. (Abstract)

Kranz, R.G., Gabbert, K.K., and M.T. Madigan. Polyhydroxyalkanoate production in Rhodobacter capsulatus:genes, mutants, expression, and physiology. Applied and Environmental Microbiology 63: 3003-3009, (1997).(Abstract)

Kranz, R.G., Gabbert, K.K., and M.T. Madigan. Positive selection systems for the discovery of novel polyester biosynthesis genes based on fatty acid detoxification. Applied and Environmental Microbiology 63: 3010-13, (1997).(Abstract)

Goldman, B.S., Beckman, D.L., Bali, A., Monika, E.M., Gabbert, K.K., and R.G. Kranz. Molecular and immunological analysis of an ABC transporter complex required for cytochrome c biogenesis. J. Mol. Biol. 268: 724-738, (1997).(Abstract)

Zeilstra-Ryalls, J.H., Gabbert K., Mouncey, N.J., Kaplan, S., R.G. Kranz. Analysis of the fnrL gene and its function in Rhodobacter capsulatus. J. Bacterial. 179:7264-7273. (1997).(Abstract)

Cullen, P.J., Bowman, W., and R.G. Kranz. In vitro reconstitution and characterization of the purified Rhodobacter capsulatus NtrB and NtrC two-component system. J. Biol. Chem. 271:6530-6536, (1996).(Abstract)

Goldman, B.S., Gabbert, K.K., and R.G. Kranz. Use of heme reporters for studies of cytochrome biosynthesis and heme transport. J. Bacteriol. 178:6338-6347 (1996).(Abstract)

Goldman, B.S., Gabbert, K.K., and R.G. Kranz. The temperature-sensitive growth and survival phenotypes of Escherichia coli cydDC and cydAB strains are due to deficiencies in cytochrome bd and are corrected by exogenous catalase and reducing agents. J. Bacteriol. 178:6348-6351 (1996).(Abstract)

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