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Summary: are relatively modest in the catalytic core domain
between structures but increase with increasing
distance from this region, as is particularly evi-
dent for the ABC signature sequence. When the
catalytic domains of one NBD in the intact
HI1470/1 transporter and one NBD in the intact
BtuCD transporter are superimposed, the relative
positions of the partner NBDs observed in these
structures are shifted by a translation or screw
component of ~4.5 A° along an axis parallel to the
interface between NBDs (Fig. 4B); this trans-
lational component repositions the two NBDs in
a direction perpendicular to that generated by the
tweezers-type motion observed between different
nucleotide states of MalK (27), which also corre-
sponds to the hinge motion between BtuD and
the closed form of MalK. Notably, the direction
of this translational shift coincides with the
direction of the twist motion observed between
the TMDs of HI1470/1 and BtuCD (Fig. 3A).
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