Department Chair and Professor
- Diploma, Universität Hamburg, Germany (1978)
- Ph.D.; Clemson University; Clemson, SC (1982)
- Post-Doc.; Roche Institute of Molecular Biology (1982-1987)
- Molecular Biology of Autotrophic Organisms
- Biochemistry and Regulation of Bacterial CO2 fixation
- Inter-Organellar Communication in Higher Plants
- Chloroplast Genome Replication and Expression
- Antibody-based Biosensors
Carboxysomes are polyhedral microcompartments found in many autotrophic bacteria. They consist of a thin shell composed of a defined set of proteins and sequester the CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase (RubisCO). The molecular mechanism by which microcompartmentalization enhances the catalytic ability of RubisCO is not fully understood, but carboxysomes are thought to serve as the final step in a carbon concentrating mechanism that provides RubisCO with the high concentrations of its substrate CO2 necessary for efficient autotrophic metabolism.
The genes encoding the carboxysome shell polypeptides and the two RubisCO subunits are arranged in an operon in the genomes of chemolithotrophs and of marine α-cyanobacteria. Upon a decrease in availability of inorganic carbon, carboxysome biogenesis in induced, the number of carboxysomes per cell, and the CO2 fixing ability of the bacteria increase dramatically.
Because of the important role(s) carboxsomes and their autotrophic bacterial hosts play in the global geochemical carbon cycle, our lab is very interested in elucidating the regulatory strategies these organisms employ to ensure that the single copies of carboxysome genes give rise to the vastly different abundances of their protein products in the microcompartment. With the help of biochemical, genomic and genetic experimental approaches in the model bacterium Halothiobacillus neapolitanus, we are dissecting the transduction of cellular and environmental signals that affect the abundance of carboxysomes and the ability of these bacteria to fix CO2 .
Selected Book Chapters:
Heinhorst, S., Cannon, G.C., and Shively, J.M.: Carboxysomes and Carboxysome-like Inclusions, in: Complex Intracellular Structures in Prokaryotes (J.M. Shively, ed.), Microbiological Monographs (2), pp. 141-165, Springer-Verlag Berlin Heidelberg (2006).
Heinhorst, S., Chi-Ham, C.L., Adamson, S.W., and Cannon, G.C.: The Somatic Inheritance of Plant Organelles. Chapter 3 in: Molecular Biology and Biotechnology of Plant Organelles (H. Daniell and C. Chase, eds), pp. 37-92. Springer-Verlag Dordrecht, NL (2004).
Selected Recent Publications:
- Tsai, Y., Sawaya, M.R., Cannon, G.C., Cai, F., Williams, E.B., Heinhorst, S., Kerfeld, C.A. and yeates, T.O.: The Structure of the Shell Protein CsoS1A from Halothiobacillus neapolitanus and its Implications for Carboxysome Function. Publ. Lib. Sci. (in press 2007).
- Heinhorst, S., Williams, E.B., Cai, F., Murin, C.D., Shively, J.M. and Cannon, G.C.: Characterization of the Carboxysomal Carbonic Anhydrase CsoSCA from Halothiobacillus neapolitanus. J. Bacteriol. 188: 8087-8094 (2006).
- Sawaya, M.R., Cannon, G.C., Heinhorst, S., Tanaka, S., Williams, E.B., Yeates, T.O. and Kerfeld, C.A.: The Structure of β- Carbonic Anhydrase from the Carboxysomal Shell Reveals a Distinct Subclass with One Active Site for the Price of Two. J. Biol. Chem. 281: 7546-7555 (2006).
- So, A.-K., Espie, G.S., Williams, E.B., Shively, J.M., Heinhorst, S. and Cannon, G.C.: A Novel Evolutionary Lineage of Carbonic Anhydrase (ε-class) is a Component of the Carboxysome Shell. J. Bacteriol. 186: 623-630 (2004).
- Cannon, G.C., Baker, S.H., Soyer, F., Johnson, D.R., Bradburne, C.E., Mehlman, J.L., Davies, P.S., Jiang, Q.L., Heinhorst, S. and Shively, J.M.: Organization of Carboxysome Genes in the Thiobacilli. Curr. Microbiol. 46: 115-119 (2003).
- Heinhorst, S., Baker, S.H., Johnson, D.R., Davies, P.S., Cannon, G.C. and Shively, J.M.: Two Copies of Form I RuBisCO Genes in Acidithiobacillus ferrooxidans ATCC 23270. Curr. Microbiol. 45: 115-117 (2002).