6MPM

Racemic M2-TM I42A crystallized from racemic detergent

Summary for 6MPM

• Entry DOI: 10.2210/pdb6mpm/pdb
• Related: 6MPL
• Descriptor: Matrix protein 2, octyl beta-D-glucopyranoside (3 entities in total)
• Functional Keywords: transmembrane, racemic, coiled-coil, membrane protein
• Biological source: Influenza A virus (strain A/Hong Kong/156/1997 H5N1 genotype Gs/Gd)
• Total number of polymer chains: 1
• Total formula weight: 3314.15

Authors

Kreitler, D.F.,Yao, Z.,Mortenson, D.E.,Forest, K.T.,Gellman, S.H. (deposition date: 2018-10-07, release date: 2019-01-30, Last modification date: 2024-10-09)

Primary citation

Kreitler, D.F.,Yao, Z.,Steinkruger, J.D.,Mortenson, D.E.,Huang, L.,Mittal, R.,Travis, B.R.,Forest, K.T.,Gellman, S.H.
A Hendecad Motif Is Preferred for Heterochiral Coiled-Coil Formation.
J. Am. Chem. Soc., 141:1583-1592, 2019

PubMed Abstract: The structural principles that govern interactions between l- and d-peptides are not well understood. Among natural proteins, coiled-coil assemblies formed between or among α-helices are the most regular feature of tertiary and quaternary structures. We recently reported the first high-resolution structures for heterochiral coiled-coil dimers, which represent a starting point for understanding associations of l- and d-polypeptides. These structures were an unexpected outcome from crystallization of a racemic peptide corresponding to the transmembrane domain of the influenza A M2 protein (M2-TM). The reported structures raised the possibility that heterochiral coiled-coil dimers prefer an 11-residue (hendecad) sequence repeat, in contrast to the 7-residue (heptad) sequence repeat that is dominant among natural coiled coils. To gain insight on sequence repeat preferences of heterochiral coiled-coils, we have examined three M2-TM variants containing substitutions intended to minimize steric clashes between side chains at the coiled-coil interface. In each of the three new crystal structures, we observed heterochiral coiled-coil associations that closely match a hendecad sequence motif, which strengthens the conclusion that this motif is intrinsic to the pairing of α-helices with opposite handedness. In each case, the presence of a hendecad motif was established by comparing the observed helical frequency to that of an ideal hendecad. This comparison revealed that decreasing the size of the amino acid side chain at positions that project toward the superhelical axis produces tighter packing, as determined by the size of the coiled-coil radius. These results provide a basis for future design of heterochiral coiled-coil pairings.

PubMed: 30645104
DOI: 10.1021/jacs.8b11246

Experimental method

X-RAY DIFFRACTION (1.4 Å)