Structure-function relationships of domains of the δ subunit in Escherichia coli adenosine triphosphatase

Biochemical and electron microscopic characterization of the F1F0 ATP Synthase from the hyperthermophilic eubacterium Aquifex aeolicus

“…In vitro [45] and in vivo [46] experiments to determine the nature of the interaction of these subunits suggested an end to end (C-termini of subunits b and d) rather than a side by side relationship. However, the exact proximity of critical residues to C-terminus of E. coli d is uncertain [47]. Dunn et al [9] summarised their work on the two E. coli b subunits [48,49] by pointing out that they both cannot interact with d in the same way.…”

Quantitative Determination of Binding Affinity of δ-Subunit in Escherichia coli F1-ATPase

“…We found that the ␦Ј fragment, lacking the C terminus of ␦, bound with the same affinity as intact ␦, suggesting that the C-terminal residues contribute little binding energy. Previous proteolytic cleavage of ␦ had suggested that the C-terminal region was not responsible for F 1 -binding (29). It is thought that the C-terminal region of ␦ binds to the C-terminal region of the b-subunit (21, 24 -26).…”

Cross-linking of the δ Subunit to One of the Three α Subunits Has No Effect on Functioning, as Expected if δ Is a Part of the Stator That Links the F1 and F0 Parts of the Escherichia coli ATP Synthase

“…The five subunits of wild-type ECF 1 , ␣, ␤, ␥, ␦, and ⑀, contain 4, 1, 2, 2, and 0 Cys residues, respectively (42,43). Of these, only one of the Cys residues of ␦, previously identified as Cys 140 , and a Cys in one of the three copies of the ␣ subunit (probably Cys 90 ), are reactive to [ 14 C]NEM in the native complex (29).…”

“…This product must be between Cys 2 of ␣ and an intrinsic Cys of ␦, because cross-linking via Cys 47 /Cys 90 does not occur in the intact ATP synthase (27)(28)(29). As with ECF 1 , small amounts of ␣-␣ and ␦ internal were also formed.…”