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2.1A Bacteriophage Phi-29 Connector
Structural highlights
FunctionPORTL_BPPH2 Forms the portal vertex of the capsid (PubMed:10801350) (PubMed:19744688, PubMed:21570409). This portal plays critical roles in head assembly, genome packaging, neck/tail attachment, and genome ejection (By similarity). The portal protein multimerizes as a single ring-shaped homododecamer arranged around a central channel (PubMed:11812138, PubMed:21570409). Binds to the 6 packaging RNA molecules (pRNA) forming a double-ring structure which in turn binds to the ATPase gp16 hexamer, forming the active DNA-translocating motor (PubMed:15886394, PubMed:11130079). This complex is essential for the specificity of packaging from the left DNA end.[UniProtKB:P13334][1] [2] [3] [4] [5] [6] Publication Abstract from PubMedThe three-dimensional crystal structure of the bacteriophage phi29 connector has been solved and refined to 2.1A resolution. This 422 kDa oligomeric protein connects the head of the phage to its tail and translocates the DNA into the prohead during packaging. Each monomer has an elongated shape and is composed of a central, mainly alpha-helical domain that includes a three-helix bundle, a distal alpha/beta domain and a proximal six-stranded SH3-like domain. The protomers assemble into a 12-mer, propeller-like, super-structure with a 35 A wide central channel. The surface of the channel is mainly electronegative, but it includes two lysine rings 20 A apart. On the external surface of the particle a hydrophobic belt extends to the concave area below the SH3-like domain, which forms a crown that retains the particle in the head. The lipophilic belt contacts the non-matching symmetry vertex of the capsid and forms a bearing for the connector rotation. The structure suggests a translocation mechanism in which the longitudinal displacement of the DNA along its axis is coupled to connector spinning. Detailed architecture of a DNA translocating machine: the high-resolution structure of the bacteriophage phi29 connector particle.,Guasch A, Pous J, Ibarra B, Gomis-Ruth FX, Valpuesta JM, Sousa N, Carrascosa JL, Coll M J Mol Biol. 2002 Jan 25;315(4):663-76. PMID:11812138[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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