IPMB Significant Results

CLONING AND MOLECULAR ANALYSIS OF THE REGULATORY FACTOR HLMYB1 IN HOP (HUMULUS LUPULUS L.) AND THE POTENTIAL OF HOP TO PRODUCE BIOACTIVE PRENYLATED FLAVONOIDS

Matoušek, J., Vrba, L., Novák, P., Patzak, J., De Keukeleire, J., Škopek, J., Heyerick, A., Roldán-Ruiz, I., De Keukeleire, D.

Fig. 1: The HlMyb1 structure in the R2R3 domain of the protein, viewed using RasWin v. 2.6.4. N and C designate the N and C terminal parts of the polypeptide, respectively. DBD designates position of DNA binding domain.

In the present work we analyzed genetic potential of Czech hops to produce medicinal compounds so-called prenylflavonoids, having multiple anti-cancerogenic, anti-osteoporotic and other biological activities. These compounds are synthesized in lupulin glands of hop cones by enzyme chs_H1, that has been isolated originally by the Czech co-authors. The potential is connected to the expression of regulatory factors, such as MYB R2R3. In our work we described the first MYB factor of hop HlMyb1 (Fig. 1). From the selected recent commercial Czech hops, the highest levels of these compounds we detected in the cultivar Agnus.

NEW PHOTOSYSTEM I ANTENNA ORGANISATION IN CHLOROPHYLL B CONTAINING CYANOBACTERIUM PROCHLOROTHRIX HOLLANDICA

Bumba, L., Prášil, O., Vácha, F.

Prochlorothrix hollandica is one of the three known species of unusual clade of cyanobacteria (formerly called "prochlorophytes") that contain chlorophyll a and b molecules bound to intrinsic light-harvesting antenna proteins. We have characterised supramolecular organisation of complex containing Photosystem I (PSI) associated with the chlorophyll a/b-binding Pcb proteins. Electron microscopy and single particle image analysis of negatively stained preparations revealed that the Pcb-PSI supercomplex consists of a central trimeric PSI surrounded by a ring of 18 Pcb subunits. Such antennae organisation was recently observed in stressed cyanobacteria. We conclude that formation of the Pcb ring around trimeric PSI represents a mechanism for increasing the light-harvesting efficiency in chlorophyll b-containing cyanobacteria.

1. The average top view projection map of the Pcb-PSI supercomplex isolated from Prochlorothrix hollandica with imposed three-fold rotational symmetry derived from image analysis of 850 negatively stained particles viewed under electron microscopy.
2. Top view projection map of the Pcb-PSI supercomplex overlaid with the cyanobacterial X-ray structure of the PSI trimer (red) and a model of transmembrane helices organisation of pcbC proteins (green).