The influence of the protein katanin 1 on the organisation of the plant cytoskeleton, an inner skeleton of cells, was confirmed by the experts from the Centre of the Region Haná for Biotechnological and Agricultural Research (CRH) in a study which was published in 2017 by Molecular & Cellular Proteomics, one of the most prominent journals on proteomics (a discipline dealing with the large-scale study of proteins and their properties). Thanks to a unique methodological combination of proteomics and cell biology (a discipline studying the functions of cells), they acquired new information on the plant cytoskeleton that may be useful in biotechnologies.
The objective of the expert team lead by Prof Jozef Šamaj was to describe in detail the role of katanin, the function of which is to “sever” microtubules. These can be depicted as a dynamic system of miniature tubular structures that form, together with actin microfilaments, the cytoskeleton of plant cells which participate in the transport of cell organelles and the division and development of cells. Correct severing of the microtubules is necessary for securing the temporal and spatial organisation of microtubules vital for plant growth and development. The researchers from the Department of Cell Biology at CRH studied two katanin mutants of a model plant, thale cress (Arabidopsis thaliana), subjected them to proteomic analysis, and compared the results with a wild-growing type of the same plant species.
“We have discovered that when katanin is not present in the mutants or its function is altered, the cytoskeleton is re-organised, which results in phenotypical changes. Compared to the wild type, the mutant plants are stunted, with a small number of flowers and seeds,” said one of the authors of the study, Tomáš Takáč. The authors have also managed to reveal yet unknown functions of this protein. According to their results, katanin connects various hormonal signals and alters the organisation of the cytoskeleton on their basis, which leads to developmental changes in the plants.
According to Olga Šamajová, a co-author of the study, another significant contribution of their works lies in the fact that they have managed to interlock the methods of proteomics, cell biology, biochemistry, and genetics. “We use the complex equipment available in the centre. Needless to say, in terms of optical microscopy in the Czech Republic, we are the best equipped institute, with advanced scanning systems for fixed as well as living cells. This enables us to provide detailed characteristics of the proteins discovered by proteomic analysis. We have managed to identify and quantify proteins with various functions which are influenced by katanin. I could name, out of the many binding proteins, at least tubulin and actin. By using the methods of cell biology, we monitored the re-organisation and random orientation of microtubules as well as the disorganisation of actin cytoskeleton in both mutants, which was caused by the afore-mentioned proteins,” said Šamajová.
The results of the three-year project may have applications in biotechnology. “These proteins can also be used in genetic modification of plants. It means that by altering the concentration of katanin we can achieve changes in the development and growth of plants. Although this protein has been relatively thoroughly investigated, a study such as the one we carried out has not yet been made,” added Takáč. According to him, katanin has been attracting significant attention by experts. It is vital for the cytoskeleton, but it has a number of other functions as well. Competition in researching this field is very strong.
The study was conducted within a project funded by the Czech Science Foundation, and Olomouc scientists collaborated even with a laboratory in the United States. The picture of microtubules from the study was featured on the front cover of the journal Molecular & Cellular Proteomics. Apart from this study, the cell biologists from CRH have published three more articles on the functions of katanin in other prestigious journals.