Spasmonemes/Centrin-Based Contraction and Bacterial Flagella

Abstract

This chapter describes that the Ca 2+ -spasmin/centrin system does not use adenosine triphosphate (ATP) for contraction, but it is responsible for re-extension. Spasmins and centrins are polymers that appear to require only the binding of Ca 2+ to change their lengths. The energy for the rotation of bacterial flagella is derived from a transmembrane ion gradient initially established by input of energy to set up the gradient. Although energy from ATP hydrolysis is involved in setting up an electrochemical gradient across the cell membrane, ATP does not directly act on the rotation of bacterial flagella. Cell motility using the energy of ion gradients is demonstrated in eukaryotic cells. The chapter discusses the molecular genetics of bacterial flagella and proteins involved in chemotaxis. Eukaryotic cilia and flagella, bacterial flagella are rigid helical structures that are rotated in one direction by the rotary motor associated with the cell membrane.