Cell Shape Model

Background

The shape of the bacterial cell is usually determined by the structures of the cell wall and bacterial cytoskeleton. Cell wall of B.subtilis is a thick layer of peptidoglycan which contains cell-wall proteins, techoic and lipotechoic acids. Peptidoglycan is a rigid structure which helps to protect the cell from osmotic pressure and mechanical damage. It also helps the cell to maintain a constant shape, while does not specifically define it. This role is played by the cytoskeleton. Bacterial cytoskeleton is largely similar to that of eukaryotes. It comprises of three types of protein structures: FtsZ, MreB and crescentin (only present in certain species) which are homologous to tubulin, actin and intermediate filaments in the eukaryotes respectively. These proteins also perform other functions in the cell, usually they are involved in cell growth and division and therefore are often essential for cell's survival. The communication between the two regulatory components is assured by a series of membrane-associated enzymes (penicillin binding proteins).

(Cabeen, Jacobs-Wagner, 2005)