Abstract:
:Members of the spectrin superfamily of proteins contain different numbers of homologous repeats arranged in tandem. Each of these consists of a three-alpha-helix motif, comprising two similarly and one oppositely directed alpha-helical segment joined by nonhelical linkers of characteristic length. The right-handed alpha-helices each display a heptad repeat in their amino acid sequences indicative of left-handed coiled-coil-like packing. We have calculated the potential number of inter-helix ionic interactions that specify the spatial arrangement of the helices in the motif in terms of both the handedness of helix connectivity (left or right) and the relative axial stagger between the three alpha-helices. All of the models examined were constrained to have optimal coiled-coil packing. For alpha-spectrin and alpha-actinin the results provide strong support for a left-handed connectivity of the three helices and axial repeat lengths of 5.05 and 6.24 nm, respectively. Furthermore, the axial staggers between homologous segments in the preferred models are identical. The insights provided into the topography of this widespread tertiary fold may prove of value to those concerned with the problem of de novo protein design.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Parry DA,Dixon TW,Cohen Cdoi
10.1016/S0006-3495(92)81893-3subject
Has Abstractpub_date
1992-04-01 00:00:00pages
858-67issue
4eissn
0006-3495issn
1542-0086pii
S0006-3495(92)81893-3journal_volume
61pub_type
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