Centre Algatech

Institute of Michrobiology, Academy of Sciences of the Czech Republic

 

GROUP MEMBERS

A glimpse of group just before final-final conclusive experiment. Members: Amelie Schober, Myriam Canonico, Sara Romandini, Eliška Trsková, Radek Kaňa, Erica Belgio, Greg Konert, Filip Charvát, Bara Šedivá, and..

 

Research topics: The research of the group is focused on basic aspect of thylakoid membrane dynamics and structure, photosynthetic proteins mobility and photoprotection in light-harvesting antennae. It uses microscopic techniques (confocal microscopy, FRAP, FCS) together with fluorescence, biochemical methods and methods of molecular biology for GFP tagging of proteins. The main aim of the group is to explore connection between thylakoid membrane structure and its bioenergetic function in light-harvesting.

NEWS:PhD and Post-doc positions aviable in following projects:

Structure and dynamics of cyanobacterial thylakoid

Photoprotective antenna protein dynamics: from live cells to algal proteoliposomes
 

(1) PROTEINS LOCALISATION IN THYLAKOID MEMBRANE

 

The primary photosynthetic rections proceeds in thylakoid membrane, situated either in specilized organel chloroplast (in algae and in higher plants) or directly cyanobacterial cells. We are interested in organisation of thylakoid membrane proteins (e.g. photosystems, light-harvesting antennae), we study how the organisation affects efficiency of light-harvesting (e.g. mechanisms photoprotection - NPQ).

The main model organism for the project is represented by single-cell cyanobacteria, Synechocystis sp. PCC 6803. Its genome is transforable by homologous recombination that allows us to make fluorescence labelling by GFP of by their analogues (see example Krynicka et al. 2014).

The dynamic process in thylakoid membrane (e.g. proteins mobility)  are then investigated using single-cell microscopic methods (FRAP, FCS) to resolve process of proteins diffusion and reorganization in thylakoid.


 

Localisation of main thylakoid membrane protein complexes in cyanobacteria Anabaena sp. PCC 7120 (see Steinbach et al. 2015)

 

(2) REGULATION OF LIGHT-HARVESTING PROTEINS

Proposed mechanisms of state transitions in cyanobacteria (see Kirilovski et al. 2014)

 

We study mechanism of photosynthetic energy conversion in light-harvesting antennae, how it is optimized by non-photochemical quenching (NPQ) or during state transitions in cyanobacteria and algae (see e.g. Kirilovski et al. 2014). Recently we have identified precence of state transitions in cryptophytes representatives Guillardia Theta (Cheregi et al. 2015).

 

(3) PROTEINS MOBILITY

Thylakoid is a higly crowded membrane formed from more then 70% by proteins. It results in restricted diffusion of proteins in thylakoid membrane  (see Kaňa et al. 2013). We try to explore factors affecting photosynthetic proteins immobility and how it is reflected in effeciency of light-harvesting (Kaňa et al. 2014).

The protein mobility is explored in situ single cell level by confocal microscopy methods including FRAP (Fluorescence Recovery After Photobleaching) and FCS (Fluorescence Correlation Spectroscopy). We want to address interconnection between thylakoid membrane structure (in a sence of proteins organisation), protein dynamic and their function in photosynthesis.


 

 

Typical setup of FRAP method (for details, see e.g. Kaňa et a. 2013).

Typical FRAP image series for PBilisome fluorescence emissiotn (for details, see e.g. Kaňa et a. 2013, 2014).

 

(4) NON-PHOTOCHEMICAL QUENCHING IN PROTEINS

Non-photochemical quenching NPQ - represents a photoprotective mechanisms dissipating excessive irradiation into heat (see Kaňa and Vass 2008). It is a preciselly controlled process affecting excesive energy dissipation in reaction centre (e.g. in extremophilic red algae, see Krupnik et al. 2013) or more often in light-harvesting antennae (see e.g. Kaňa et al. 2012).

 

 

Slow temperature increase induced by irradiation measured by theromocamera (for details, see Kaňa and Vass 2008).

Typical quenching analysis of Rhodomonas salina cells. (for more details, see Kaňa et al. 2012)

 

Isolated antennae complexes of Rhodomonas salina cells. (for more details, see Kaňa et al. 2012)

We focuse on mechanisms of NPQ in red-clade of photosynthetic organisms that are typical in huge variability in antennae proteins and pigment compositions. Our main model organisms are represented by Chromera velia (photosynthetic colpedelid algae) and cryptophytes (Rhodomonas salina, Guillardia Theta). These algae species represents a good models to study NPQ mechanisms dependent on xanthophyle cycle (C. velia - see Kotabová et al. 2011) and independent to any xanthophyll cycle (see Kaňa et al. 2012. Cheregi et al. 2015).

 

 

(5) NEW BIOPHYSICAL METHODS IN PHOTOSYNTHESIS

We have adapted several new biophysical methods for photosynthesis research. It includes spectrally resolved fluorescence induction (SRFI) allowing spectral detection of fluorescence induction and fluorescence parameters (e.g. NPQ, see .....) and and detection fluorescence induction (PAM-like curves) for various chromophores simultaneously.

We have also developed new method of cryoimaging (see Steinbach et al. 2015) allowing separate depetection of PSII fluorescence and red shifted PSI fluorescence at 77K.

 

Typical time-course of Spectrally Resolved Fluorescnece Induction Method (SRFI) for cyanobacteria.