Fig. 4: SecA dynamics derived from PPXD movement depending on nucleotide states in protein translocation.
From: AFM observation of protein translocation mediated by one unit of SecYEG-SecA complex
a Distribution of the High and Low forms in different nucleotide conditions, as counted from HS-AFM snapshot images. SecA can transition to the Low form upon interacting with its substrate, as opposed to being in the High state in the resting condition. The number of particle images for each state is as follows: Apo (n = 100), 5 mM ATP (n = 284), 1 mM AMP-PNP (n = 140), 5 mM ADP-AlF3 (n = 174), 5 mM ADP (n = 134), 5 mM ATP, and 50 mM NaH₂PO₄ (n = 134). b Schematic representation of SecA conformational dynamics during the ATP hydrolysis cycle. The diagram illustrates SecA conformational transitions between High (wide-open) and Low (closed) conformations in response to nucleotide state changes. Upon ATP binding, SecA adopts the High conformation, which transitions to the Low conformation after ATP hydrolysis. Following phosphate release, SecA returns to the High conformation.
