Premium
Structural framework for DNA translocation via the viral portal protein
Author(s) -
Lebedev Andrey A,
Krause Margret H,
Isidro Anabela L,
Vagin Alexei A,
Orlova Elena V,
Turner Joanne,
Dodson Eleanor J,
Tavares Paulo,
Antson Alfred A
Publication year - 2007
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601643
Subject(s) - biology , dna , protein subunit , capsid , bacteriophage , biophysics , protein structure , crystallography , virus , genetics , biochemistry , gene , chemistry , escherichia coli
Tailed bacteriophages and herpesviruses load their capsids with DNA through a tunnel formed by the portal protein assembly. Here we describe the X‐ray structure of the bacteriophage SPP1 portal protein in its isolated 13‐subunit form and the pseudoatomic structure of a 12‐subunit assembly. The first defines the DNA‐interacting segments (tunnel loops) that pack tightly against each other forming the most constricted part of the tunnel; the second shows that the functional dodecameric state must induce variability in the loop positions. Structural observations together with geometrical constraints dictate that in the portal–DNA complex, the loops form an undulating belt that fits and tightly embraces the helical DNA, suggesting that DNA translocation is accompanied by a ‘mexican wave’ of positional and conformational changes propagating sequentially along this belt.