The family of the F-, V-, and A-type ATPase enzyme complexes represent the most abundant rotary ATPases. They are of great medical relevance since they play key roles in several diseases and disorders. Detailed theoretical models of their rotation-coupled catalysis-transport mechanism are still limited by the fact that in vivo proton transport and rotation are much more difficult to measure than enzymatic activity. Moreover, the Fo/Vo/Ao domains are still challenging for structural biology. Ductins are a family of homologous membrane proteins with 2 or 4 transmembrane alpha-helices. The active forms of the Ductins are membranous ring- or star-shaped oligomeric assemblies and they provide various pore, channel, and gap-junction functions and assist in membrane fusion processes. The c-ring (rotor) proteins of the F-, V-, and A-ATPases also belong to the Ductin family. Increasing evidence suggests that the c-ring proteins have an alternative, non-enzymatic functions. Since fine regulation of the Fo/Vo/Ao functions and the Ductin assemblies are far from being fully understood, the overall purpose of this Research Topic is to gain more details on the coupled catalysis-rotation-transport mechanism of the rotary ATPases, which requires innovative measurements of the rotation and proton transport, in addition to the enzymatic activity, preferably under standardized conditions. Since the c-ring assembly-disassembly appears to be a regulated process under certain conditions, we also aim at gathering papers that provide new concepts and angles of view on common and distinctive features of the c-ring of rotary ATPases and other Ductin protein assemblies, and how their assembly and function are regulated by newly explored mechanisms and factors. For instance, little is known about the effect of lipids and other membrane components or metal ions on the c-ring and Ductin assemblies and on the rotary mechanism of proton transport by Fo/Vo/Ao. More data about the non-rotor, hence non-enzymatic functions of the c-ring proteins are also welcome. Newly explored regulatory factors of these rotary ATPases have an immediate impact on drug design targeting diseases where these enzymes are desirable drug targets. Original articles and reviews are welcome under the themes that include but are not limited to the following: • Regulatory processes and factors acting on the Fo/Vo/Ao domains • The role of the membrane bilayer in regulating F-, V- and A-ATPase function • Non-rotor functions of c-ring proteins • Measurements of the rotation and proton transport in rotary ATPases under comparable conditions • Structural biology data on the F-, V- and A-type rotary ATPases • Factors affecting the assembly of Ductin proteins • Structural and functional links between the c-ring and other Ductin proteins • Models of the rotary mechanism and proton transfer in the Fo/Vo/Ao domain • Data of biological, physiological, and medical relevance of the rotary ATPases • Data on structure-function relationship and regulatory factors
The family of the F-, V-, and A-type ATPase enzyme complexes represent the most abundant rotary ATPases. They are of great medical relevance since they play key roles in several diseases and disorders. Detailed theoretical models of their rotation-coupled catalysis-transport mechanism are still limited by the fact that in vivo proton transport and rotation are much more difficult to measure than enzymatic activity. Moreover, the Fo/Vo/Ao domains are still challenging for structural biology. Ductins are a family of homologous membrane proteins with 2 or 4 transmembrane alpha-helices. The active forms of the Ductins are membranous ring- or star-shaped oligomeric assemblies and they provide various pore, channel, and gap-junction functions and assist in membrane fusion processes. The c-ring (rotor) proteins of the F-, V-, and A-ATPases also belong to the Ductin family. Increasing evidence suggests that the c-ring proteins have an alternative, non-enzymatic functions. Since fine regulation of the Fo/Vo/Ao functions and the Ductin assemblies are far from being fully understood, the overall purpose of this Research Topic is to gain more details on the coupled catalysis-rotation-transport mechanism of the rotary ATPases, which requires innovative measurements of the rotation and proton transport, in addition to the enzymatic activity, preferably under standardized conditions. Since the c-ring assembly-disassembly appears to be a regulated process under certain conditions, we also aim at gathering papers that provide new concepts and angles of view on common and distinctive features of the c-ring of rotary ATPases and other Ductin protein assemblies, and how their assembly and function are regulated by newly explored mechanisms and factors. For instance, little is known about the effect of lipids and other membrane components or metal ions on the c-ring and Ductin assemblies and on the rotary mechanism of proton transport by Fo/Vo/Ao. More data about the non-rotor, hence non-enzymatic functions of the c-ring proteins are also welcome. Newly explored regulatory factors of these rotary ATPases have an immediate impact on drug design targeting diseases where these enzymes are desirable drug targets. Original articles and reviews are welcome under the themes that include but are not limited to the following: • Regulatory processes and factors acting on the Fo/Vo/Ao domains • The role of the membrane bilayer in regulating F-, V- and A-ATPase function • Non-rotor functions of c-ring proteins • Measurements of the rotation and proton transport in rotary ATPases under comparable conditions • Structural biology data on the F-, V- and A-type rotary ATPases • Factors affecting the assembly of Ductin proteins • Structural and functional links between the c-ring and other Ductin proteins • Models of the rotary mechanism and proton transfer in the Fo/Vo/Ao domain • Data of biological, physiological, and medical relevance of the rotary ATPases • Data on structure-function relationship and regulatory factors