Caracterizacion estructural y evolutiva del complejo FtsW/FtsI de Escherichia coli

Abstract

The bacterial division es an esential process that is executed by a complex of proteins, called divisome. FtsW and FtsI are membrane proteins part of this machinery, that form a complex. This complex is formed in the late phase of division after the chromosome segregation and FtsQ/FtsB/FtsL complex binding. However, the FtsW/FtsI complex have a low number of molecular evidences about its function and structure. FtsI has only one transmembrane span domain. It belongs to the penicillin binding protein family and has transpeptidase activity. FtsW is a ten-transmembrane span protein, without a demonstrated function or structure. It doesn't have any homolog that could suggest a specific folding. The way both proteins interact each other to form the complex is also a mistery. In this Thesis both proteins was studied in deep, from structure to evolution. These analyses support the hypothesis of FtsW being a far-member of the transglycosilase family, so its most probable function is to extend the peptidoglycan chains from the precursor Lipid II. After that, FtsI can crosslink those chains. As the complex has both enzymatic activities, it is possible to extend the peptidoglycan chain in the direction of constriction, creating the new poles of the daughter cells. During this Thesis it was possible to obtain structural models for both proteins. The FtsW model was supported by some experiments and the FtsI model incude its transmembrane domain. Moreover, specific residues and regions of both proteins are proposed to form the contact interfase in the complex. Finally, the evolution of the corresponding genes was analyzed in all the bacteria kingdom. The FtsW/FtsI is very conserved and probably is an element that evolved together the peptidoglycan wall itself.