Bacteriophage P22 tail accessory factor GP26 is a long triple-stranded coiled-coil

Dewan Andrews, James S. Butler, Jawdat Al-Bassam, Lisa Joss, Danella A. Winn-Stapley, Sherwood Casjens, Gino Cingolani

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


P22 is a well characterized tailed bacteriophage that infects Salmonella enterica serovar Typhimurium. It is characterized by a "short" tail, which is formed by five proteins: the dodecameric portal protein (gp1), three tail accessory factors (gp4, gp10, gp26), and six trimeric copies of the tail-spike protein (gp9). We have isolated the gene encoding tail accessory factor gp26, which is responsible for stabilization of viral DNA within the mature phage, and using a variety of biochemical and biophysical techniques we show that gp26 is very likely a triple stranded coiled-coil protein. Electron microscopic examination of purified gp26 indicates that the protein adopts a rod-like structure ∼210 Å in length. This trimeric rod displays an exceedingly high intrinsic thermostability (Tm ∼85°C), which suggests a potentially important structural role within the phage tail apparatus. We propose that gp26 forms the thin needle-like fiber emanating from the base of the P22 neck that has been observed by electron microscopy of negatively stained P22 virions. By analogy with viral trimeric coiled-coil class I membrane fusion proteins, gp26 may represent the membrane-penetrating device used by the phage to pierce the host outer membrane.

Original languageEnglish (US)
Pages (from-to)5929-5933
Number of pages5
JournalJournal of Biological Chemistry
Issue number7
StatePublished - Feb 18 2005
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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