Farkli bitki türlerinden seçilmiş xth enzimlerinin klonlama, ekspresyon ve in siliko analizleri

During the plant life cycle, the plant cell wall undergoes alterations and adaptations which are accomplished by enzymes able to modify cell wall polysaccharides. A significant and abundant non-cellulosic β-linked polysaccharide called xyloglucan binds cellulose microfibrils to create supporting structures in cell wall of the plant. Modifications in the plant cell wall are carried out by a crucial modifying enzyme xyloglucan endotransglycosylase/hydrolases (XTHs), and is divided into six groups (Group I, II, III-A, III-B, IV and EG16) depending on the similarities of their amino acid sequences. Understanding the roles of these enzymes that change the carbohydrate matrix is essential for altering cell wall characteristics to increase yield and preserve the plant from external factors. In order to shed light on the working process of XTH in different species and elucidate the relationships between the plants and their polysaccharides substrates, we were selected the AtXTH30, Arabidopsis thaliana XTH gene ,which belongs to a poorly studied sub-clade Group III-B; and EtXTH1, Equisetum telmateia XTH gene, which has not been enzymatically characterized. The objective of this thesis was to investigate A. thaliana and Equisetum XTH enzymes at the molecular, transcriptomic, and protein levels to gain a better insight of how these enzymes work and what functions they serve. Equisetum telmateia. EtXTH1 and AtXTH30 enzymes could not be heterologously expressed during the period of this study. However, XTH genes of Arabidopsis thaliana, Equisetum family members Equisetum telmateia, Equisetum hymale and Equisetum diffusum were identified by transcriptome analyses. Phylogenetic and transcriptome analyses revealed that catalytic motifs of XTH genes were maintained and, in certain circumstances, varied from species to species by amino acid substitutions, influencing the enzymatic activity of specific XTH genes. Highly conserved protein motifs were determined and AtXTH30 protein structure was modelled. Moreover, generated phylogenetic tree provide information about the relationship between the XTH enzymes that could be broadly capable of transferase/hydrolase activity.