Structural bioenergetics and energy transduction mechanisms

Life depends on transduction processes that couple cellular metabolism to e nvironmental energy sources such as light or reduced compounds. These prima ry energy sources must be efficiently converted into forms that can be util ized by cells If or biosynthesis, motility, transport, regulation, and othe r metabolic functions. In recent years, there has been an explosive increas e in the determination of structures for proteins mediating energy transduc tion processes. These developments provide the opportunity to evaluate the structural basis for the efficient coupling of two energetic processes, whi ch defines the area of structural bioenergetics. Here, we present some gene ral features of energy transduction processes, including arguments that eff ective coupling of two processes by a transduction protein occurs by way of conformational States that are common to the catalysis of each process. Th is is illustrated by examples from the nucleotide switch family of proteins , with emphasis on the nitrogenase system where Am hydrolysis is coupled to an: electron transfer reaction. (C) 1999 Academic Press.