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

doi:10.1074/jbc.c400513200

Dewan Andrews, James S Butler + Show 5 more

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https://doi.org/10.1074/jbc.c400513200

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Abstract

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 approximately 210 angstroms in length. This trimeric rod displays an exceedingly high intrinsic thermostability (T(m) approximately 85 degrees 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.

Highlights

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, three tail accessory factors, and six trimeric copies of the tail-spike protein
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 negatively stained P22 virions revealed a thin fiber protruding from the base of the phage tail [5, 6]

Summary

Introduction

P22 is a well characterized tailed bacteriophage that infects Salmonella enterica serovar Typhimurium. 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 ϳ210 Å in length.

Results

Conclusion