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Research Programmes

 

Glycobiochemistry

Doc. RNDr. Michaela Wimmerová, Ph.D.
Research Group Leader

THEMATIC RESEARCH FOCUS

RESEARCH AREAS

  • Carbohydrate-binding proteins involved in host-pathogen interactions
  • Human glycosyltransferases and their role in cancerogenesis
  • Glycosyltransferases participating in mycobacterial cell wall synthesis
  • Protein engineering of lectins
  • Biomolecular interactions

MAIN OBJECTIVES

  • To study the therapeutical aspects of recognition and adhesion phenomena in host-pathogen interactions.
  • Investigations of the structure and interactions of biomacromolecules and their relation to the functions of living systems, disease and therapy.

CONTENT OF RESEARCH

Research is focused on structure-function studies of proteins, which participate in oligosaccharide syntheses (glycosyltransferases), or specific recognition (lectins). Carbohydrates are essential for life and, in addition to their classical role as structural and energy storage components, they play crucial roles in many recognition events. A specific recognition of glycoconjugates is an important event in biological systems and participates in numerous physiological and pathophysiological processes including cell signalling, diff erentiation, fertilisation, infl ammatory response, as well as in cancerogenesis or pathogen-cell adhesion and recognition. The multiple roles of carbohydrates arise from the stability and the stereochemical diversity of glycosidic bonds.

The life cycles of pathogenic bacteria, fungi and viruses require a specifi c recognition of host tissue for adhesion and subsequent invasion. A common strategy often used by pathogens involves binding to the host glycoconjugates through sugar-binding proteins that can display exquisite specifi city for the target tissue. For many pathogenic organisms, the ability to adhere to host tissues is essential to initiate an infection. Oligosaccharidemediated recognition and adhesion are, for example, key points in the early steps of P. aeruginosa infection because they are followed by processes such as chronic colonisation and biofi lm formation together with alginate production under the control of quorum sensing. These last adaptive changes of the bacteria make their eradication diffi cult because when in the biofi lm phenotype, the bacteria become resistant to antibiotic drugs. This brings new challenges into the therapeutical area because the inhibition of protein-carbohydrate interaction could lead to the inhibition of pathogen recognition and adhesion to the host cell.

One of the groups of proteins we are interested in is a group of lectins from human opportunistic pathogens, such as Pseudomonas aeruginosa, Burkholderia cepacia complex, Aspergillus fumigatus, etc. These organisms are usually widely spread around the population and are not dangerous to healthy individuals. On the other hand, they become highly virulent in contact with immunocompromised patients. Developed infections are associated with high morbidity and mortality of the infected people especially of individuals under mechanical ventilation and patients suffering from cystic fibrosis.

We use a multidisciplinary approach to study the recognition and adhesion phenomena of pathogens including bacteria, viruses, and fungi to human tissue. We have been identifying new potential protein targets using bioinformatics tools, and they have been prepared in recombinant form using molecular biology approaches. The complementary techniques of binding experiments, isothermal titration microcalorimetry, surface plasmon resonance and high resolution X-ray crystallography are used to decipher the thermodynamic and structural basis for the unusually high affinity binding of lectins from pathogens to their host carbohydrates. In addition, site-directed mutagenesis in combination with structural and functional studies allow us to understand the roles of particular amino acids in the fine definition of sugar specificity and preference.

Such a structure-function correlation of protein/carbohydrate interaction forms the basis for the rational design of carbohydrate-based drugs directed against adhesion and virulence.

KEY RESEARCH EQUIPMENT

PLANNED RESEARCH INFRASTRUCTURE

Core Facility

The research group will be one of the principal users of the equipment available within CEITEC Single Crystal X-ray Difraction Core Facility.

CURRENT RESEARCH INFRASTRUCTURE

The current infrastructure includes SPR Biacore 3000, isothermal titration calorimeters VP-ITC and ITC200, differential scanning calorimeter VP-DSC, dynamic light scattering plate reader DynaPro Plate Reader, CD spectrophotometer Jasco 850, analytical ultracentrifuge ProteomLab XL-1, crystallisation robot Mosquito, automatic visualisation and documentation system for crystallisation Rigaku Desktop Minstrel UV + Plate Hotel Gallery 160, automatic pipetting station Tecan Evo150, automatic colony picker PM-1s, AKTA Purifier, AKTA FPLC, common equipment for molecular biology and biochemistry work.

MAIN PROJECTS

  • Preparation of lectins with high specifi city and affi nity (P207/11/P185), Czech Science Foundation, 2011-2013, M. Pokorna, Masaryk University.
  • Structure-function studies on lectins and adhesins from microbial patogens (GA303/06/0570), Czech Science Foundation, 2006-2008, M. Wimmerova, Masaryk University.
  • Lectins from human pathogens – structure, function, engineering (GA303/09/1168), Czech Science Foundation, 2009-2012, M. Wimmerova, Masaryk University.
  • Design of Carbohydrates and Glycomimetics as Antibacterial and Antiviral Drugs (ME08008), Ministry of Education, Youth and Sports, 2008-2012, M. Wimmerova, Masaryk University.
  • Structure-functional characterisation of oxidoreductases acting on nitrogenous regulatory compounds in plants (GA522/08/0555), Czech Science Foundation, 2008-2012, M. Šebela, Palacky University Olomouc, M. Wimmerova, Masaryk University.

SELECTED PUBLICATIONS

  • SULAK, O., CIOCI, G., DELIA, M., LAHMANN, M., VARROT, A., IMBERTY, A., WIMMEROVA, M. A TNF-like trimeric lectin domain from the opportunistic pathogen Burkholderia cenocepacia with specifi city for fucosylated human histo-blood group antigens. Structure. 2010, 18, p. 59-72.
  • POKORNA, M., CIOCI, G., PERRET, S., REBUFFET, E., KOSTLANOVA, N., ADAM, J., GILBOA-GARBER, N., MITCHELL, E., P., IMBERTY, A., WIMMEROVA, M. Unusual Entropy Driven Affi nity of Chromobacterium violaceum Lectin CV-IIL towards Fucose and Mannose. Biochemistry. 2006, 45, p. 7501-7510.
  • IMBERTY, A., MITCHELL, E., P., WIMMEROVA, M. Structural basis of high-affi nity glycan recognition by bacterial and fungal lectins. Curr. Opin. Struct. Biol. 2005, 15, p. 523-534.
  • WIMMEROVA, M., MITCHELL, E., SANCHEZ, J.-F., GAUTIER, C., IMBERTY, A. Crystal structure of fungal lectin: Six-bladed s –propeller fold and novel fucose recognition mode for Aleuria aurantia lectin. J. Biol. Chem. 2003, 278, p. 27059-27067.
  • MITCHELL, E., HOULES, C., SUDAKEVITZ, D., WIMMEROVA, M., GAUTIER, C., PEREZ, S., WU, M., A., GILBOA-GARBER, N., IMBERTY, A. Structural basis for oligosaccharide-mediated adhesion of Pseudomonas aeruginosa in the lungs of cystic fi brosis patients. Nature Struct. Biol. 2002, 12, p. 918-921.
 

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