• Expertise
• Research Projects
• Teaching
• Publications (2000 -2009)

Department of Bioenergetics

Institute of Biology
University of Stuttgart,
Pfaffenwaldring 57,
D-70550 Germany

Tel.: +711 -685 650 40; Fax: +711 - 685 650 96
Email: robin.ghosh@bio.uni-stuttgart.de
 
 
 
 

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Expertise:

General Biochemistry,

Protein Biochemistry and Biophysical Chemistry

Bioenergetics

Microbial Physiology of Phototrophic bacteria

Molecular Biology of Phototrophic bacteria

Overview

The main research interests of my group in recent years have concentrated on biochemical and genetic aspects of bacterial photosynthesis, particularly in:

Detailed summary of research goals

(a) Determination of the the three-dimensional structure of the bacterial light-harvesting complex I from R. rubrum at high resolution by means of X-ray crystallography or electron crystallography

2D crystals of isolated LH1 complexes reconstituted into phospholipid membranes

The high-resolution structure of these very different complexes, which are nevertheless constructed from very similiar protein building blocks, will facilitate the elucudation of the molecular principles determining the high efficiency of light-energy transfer between protein-(non-covalently) bound bacteriochlorophyll chromophores.

In addition, we expect to understand the nature of the specific long-range protein-protein interactions between complexes which are causal for the structural differentiation of the photosynthetic membrane. The structural principles deduced should have profound implications not only for an understanding of the structural organization of the photosynthetic membrane of purple bacteria, but also for the design of new computer chips employing optical signal processing.

(b) Determination of the nature of the interaction between the light-harvesting complexes and the reaction centre

2D crystals of the LH1-Reaction centre photosynthetic unit

(c) Design of membrane protein arrays - combinatorial screening using fiberoptic spectroscopy
The unique aggregational properties of the small light-harvesting polypeptides make them ideal candidates for design of protein-pigment arrays for application in biochip technology. Several complementary technologies facilitate this approoach: (1) the polypeptides and mutants thereof can be synthesized in large quantities by gene technology; (2) Refolding procedures exist to reconstitute the polypeptides in vitro with porphyrin pigments; (3) mutants can also be readily expressed in the native organism; (4) modified pigment-polypeptide binding sites can be easily screened using spectroscopy; (5) recently we have developed rapid (millisecond) fiber-optic spectroscopic techniques for measuring the complete optical spectra of light-harcesting mutants from single bacterial colonies. This now means that large combinatorial libraries of mutants can be screened rapidly for modified pigment-protein interactions.

(d) Studies of structural and motional events in membrane proteins using solid-state NMR spectroscopy
Only a small amount of detailed information concerning the structural and motional characteristics of the amino acid residues in membrane proteins is available at the present time. Solid-state NMR spectroscopy (¹⁹F, ¹³C, ¹⁵N, ²H) is an ideal technique for yielding this information but has not been widely applied so far.The small size of the light-harvesting polypeptides, their availability in large quantities and their genetic accessibility make them ideal candidates for examining fundamental aspects of protein structure using solid-state NMR.

(e) Characterization of periplasmic and outer membrane fractions of R. rubrum
Despite the fact that R. rubrum has been a popular organism for the study of photosynthesis for many years, there is a paucity of information concerning the composition of the periplasmic and outer membrane fractions. As these data are essential for studies of gene expression is these compartments,we have begun to assign their biochemical composition. An IEF profile of haemoproteins contained in the periplasmic fraction is shown below as an example.

Teaching (German version, English version in preparation)Press here to see Teaching Page
 

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Publications (2000-2009)

PUBLICATIONS LIST

1. Grammel, H., and Ghosh, R. (2008) J. Bacteriol.190, 4912-4921: Redox state dynamics of ubiquinone-10 imply cooperative regulation of photosynthetic membrane expression in Rhodospirillum rubrum.

2. Klamt, S., Grammel, H., Straube, R., Ghosh, R. and Gilles, E.-D. (2008) Molecular Systems Biology 4, 1-19: Modelling the electron transport chain of purple non-sulpur bacteria

3. Gerken, U., Erhardt, D., Bär, G., Ghosh, R. and Kuhn, A. (2008) Biochemistry 47, 6052-6058: Initial binding process of the membrane insertase YidC with ist substrate Pf3 coat protein is irreversible.

4. Lupo, D., and Ghosh, R. (2004) J. Bacteriol. 186, 5585-5595. The reaction center H-subunit is not required for high levels of light-harvesting complex 1 in Rhodospirillum rubrum mutants.

5. Gärtner, P., Port, H., and Ghosh, R. (2004) J. Luminesc. 108, 111-116. FS-study on energy relaxation in light-harvesting 1 (LH1) complexes from Rhodospirillum rubrum for carotinoids of different conjugation lengths.

6. Gerken, U., Lupo, D., Wrachtrup, J., and Ghosh, R. (2003) Biochemistry, 42, 10354-10360. The circular symmetry of the light-harvesting I complex from Rhodospirillum rubrum is not perturbed by interaction with the reaction center.

7. Gerken, U., Jelezko, F., Götze, B., Branschädel, M., Tietz, C., Ghosh, R., Wrachtrup, J. (2003) J. Phys. Chem. B, 107, 338-343. The membrane environment reduces the accessible conformational space available to an integral membrane protein.

8. Grammel, H., Gilles, E.-D., and Ghosh, R. (2003) Appl.Environ.Microbiol. 69, 6577-6586. Microaerophilic cooperation of reductive and oxidative pathways allows maximal photosynthetic membrane biosynthesis in Rhodospirillum rubrum.

9. Zhang, S. C., Ghosh, R., and Jeske, H. (2002) Archiv. Virol. 147, 2349-2363. Subcellular targetting of Abutilon mosaic geminivirus movement protein BC1.