Crystal structure of the ϵ subunit of the proton-translocating ATP synthase from Escherichia coli

Abstract

Sequence alignments of a number of epsilon subunits from diverse sources suggest that the C-terminal domain, which is absent in some species, is not essential for function. In the crystal the N-terminal domains of two epsilon subunits make a close hydrophobic interaction across a crystallographic twofold axis. This region has previously been proposed as the contact surface between the epsilon and gamma subunits in the complete F1-ATPase complex. In the crystal structure we observe what is apparently a stable interface between the two domains of the epsilon subunit, consistent with the fact that the crystal and solution structures are quite similar despite close crystal packing. This suggests that a gross conformational change in the epsilon subunit, to transmit the effect of proton translocation to the catalytic domain, is unlikely, but cannot be ruled out.

The Conformation of the ε- and γ-Subunits within theEscherichia coli F1 ATPase

“…In bovine F 1 this region forms a compact helical hairpin, analogous to that seen in the structure of the isolated E. coli ⑀-subunit (8,20,21). In contrast, in the E. coli structure this helical region appears to be extended, with a conformation similar to that seen in the structure of the ␥Ј⑀ complex (Fig.…”

“…Conformation of the ⑀-Subunit-It was shown previously that the structure of the isolated E. coli ⑀-subunit (20,21) differed from that in the ␥Ј⑀ complex (9). This subunit consists of an N-terminal ␤-sandwich domain of about 80 residues plus a C-terminal ␣-helical region of about 50 residues.…”

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“…The two small F 1 subunits δ and could not be detected in the X-ray density maps (Abrahams et al 1994), but more recently the δ subunit structure has been determined by NMR (Wilkens et al 1997) and the structure by both NMR (Wilkens et al 1995) and X-ray diffraction (Uhlin et al 1997). From several crosslinking studies the location of these subunits with respect to the other F 1 subunits could be determined.…”

Rotor/Stator Interactions of the ϵ Subunit in Escherichia coli ATP Synthase and Implications for Enzyme Regulation

“…The structure of purified E. coli ⑀ subunit (23,24) is essentially identical to that of its homolog in bovine mitochondrial F 1 (MF 1 ) 1 (25). In each case, an N-terminal ␤-sandwich domain is connected by a loop to a smaller C-terminal domain that consists of a pair of antiparallel ␣-helices, with the second helix packed against one edge of the ␤-sandwich to give a compact "closed" structure (Fig.…”