Informatics and medicine--from molecules to populations.

OBJECTIVES: To clarify challenges and research topics for informatics in health and to describe new approaches for interdisciplinary collaboration and education. METHODS: Research challenges and possible solutions were elaborated by scientists of two universities using an interdisciplinary approach, in a series of meetings over several months. RESULTS AND CONCLUSION: In order to translate scientific results from bench to bedside and further into an evidence-based and efficient health system, intensive collaboration is needed between experts from medicine, biology, informatics, engineering, public health, as well as social and economic sciences. Research challenges can be attributed to four areas: bioinformatics and systems biology, biomedical engineering and informatics, health informatics and individual healthcare, and public health informatics. In order to bridge existing gaps between different disciplines and cultures, we suggest focusing on interdisciplinary education, taking an integrative approach and starting interdisciplinary practice at early stages of education.

Molecular probes: what is the range of their interaction with the environment?

We performed pressure-tuning hole-burning experiments on a modified cytochrome c protein in a glycerol/buffer glass. The shift and the broadening of the holes were investigated for various frequencies within the inhomogeneous band. On the basis of a simple model, we were able to estimate the interaction range between chromophore and protein. It is approximately 4.5 A. The parameters that enter the model are the compressibility, the static mean-square displacement, the inhomogeneous width, and the average spectral shift per pressure. From this result and from our experiments on pressure-induced denaturing, we conclude that water molecules have to be brought very close to the chromophore during the denaturation process.

Trehalose effect on low temperature protein dynamics: fluctuation and relaxation phenomena.

We performed spectral diffusion experiments in trehalose-enriched glycerol/buffer-glass on horseradish peroxidase where the heme was replaced by metal-free mesoporphyrin IX, and compared them with the respective behavior in a pure glycerol/buffer-glass (Schlichter et al., J. Chem. Phys. 2000, 112:3045-3050). Trehalose has a significant influence: spectral diffusion broadening speeds up compared to the trehalose-free glass. This speeding up is attributed to a shortening of the correlation time of the frequency fluctuations most probably by preventing water molecules from leaving the protein interior. Superimposed to the frequency fluctuation dynamics is a relaxation dynamics that manifests itself as an aging process in the spectral diffusion broadening. Although the trehalose environment speeds up the fluctuations, it does not have any influence on the relaxation. Both relaxation and fluctuations are governed by power laws in time. The respective exponents do not seem to change with the protein environment. From the spectral dynamics, the mean square displacement in conformation space can be determined. It is governed by anomalous diffusion. The associated frequency correlation time is incredibly long, demonstrating that proteins at low temperatures are truly nonergodic systems.

CYC2 encodes a factor involved in mitochondrial import of yeast cytochrome c.

The gene CYC2 from the yeast Saccharomyces cerevisiae was previously shown to affect levels of mitochondrial cytochrome c by acting at a posttranslational step in cytochrome c biosynthesis. We report here the cloning and identification of the CYC2 gene product as a protein involved in import of cytochrome c into mitochondria. CYC2 encodes a 168-amino-acid open reading frame with at least two potential transmembrane segments. Antibodies against a synthetic peptide corresponding to the carboxyl terminus of the predicted sequence were raised. These antibodies recognize multiple bands on immunoblots of mitochondrial extracts. The intensities of these bands vary according to the gene dosage of CYC2 in various isogenic strains. Immunoblotting of subcellular fractions suggests that the CYC2 gene product is a mitochondrial protein. Deletion of CYC2 leads to accumulation of apocytochrome c in the cytoplasm. However, strains with deletions of this gene still import low levels of cytochrome c into mitochondria. The effects of cyc2 mutations are more pronounced in rho- strains than in rho+ strains, even though rho- strains that are CYC2+ contain normal levels of holocytochrome c. cyc2 mutations affect levels of iso-1-cytochrome c more than they do levels of iso-2-cytochrome c, apparently because of the greater susceptibility of apo-iso-1-cytochrome c to degradation in the cytoplasm. We propose that CYC2 encodes a factor that increases the efficiency of cytochrome c import into mitochondria.