Modulation of yeast F-actin structure by a mutation in the nucleotide-binding cleft

摘要: Although the actin sequence is very highly conserved across evolution, tissue-specific expression of different isoforms in high eukaryotes suggests that carry out functions. However, little information exists about either differences filaments made from actins or effects on filament structure caused by various mutations have been introduced to gain insight into function. Using electron microscopy and three-dimensional reconstruction, we studied yeast rabbit skeletal muscle actin, two proteins with 88% homologous sequences, assessed changes introduction S14A mutation actin. Elimination S14 hydroxyl group, assumed bind gamma-phosphate actin-bound ATP, results a 40 60-fold decrease actin's affinity for ATP. We show displays less extensive contacts between long-pitch helical strands than does large cooperativity within previously observed Finally, demonstrate narrows cleft lobes subunit strengthens inter-strand connections F-actin.