DNA packaging-associated hyper-capsid expansion of bacteriophage t3.
Evidence that in vivo bacteriophage T3 DNA packaging includes capsid hyper-expansion that is triggered by lengthening of incompletely packaged DNA (ipDNA) is presented here. This evidence includes observation that some of the longer ipDNAs in T3-infected cells are packaged in ipDNA-containing capsids with hyper-expanded outer shells (HE ipDNA-capsids). In addition, artificially induced hyper-expansion is observed for the outer shell of a DNA-free capsid. Detection and characterization of HE ipDNA-capsids are based on two-dimensional, non-denaturing agarose gel electrophoresis, followed by structure determination with electron microscopy and protein identification with SDS-PAGE/mass spectrometry. After expulsion from HE ipDNA-capsids, ipDNA forms sharp bands during gel electrophoresis. The following hypotheses are presented: (1) T3 has evolved feedback-initiated, ATP-driven capsid contraction/hyper-expansion cycles that accelerate DNA packaging when packaging is slowed by increase in the packaging-resisting force of the ipDNA and (2) each gel electrophoretic ipDNA band reflects a contraction/hyper-expansion cycle.
Serwer
Philip
P
Department of Biochemistry, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA. serwer@uthscsa.edu <serwer@uthscsa.edu>
Wright
Elena T
ET
Hakala
Kevin
K
Weintraub
Susan T
ST
Su
Min
M
Jiang
Wen
W
D017903:Bacteriophage T3 / Q000502:physiology*; D002213:Capsid / Q000378:metabolism* / Q000648:ultrastructure; D042003:DNA Packaging; D004279:DNA, Viral / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D013058:Mass Spectrometry; D008854:Microscopy, Electron; D008954:Models, Biological; D014764:Viral Proteins / Q000032:analysis
D004279:DNA, Viral; D014764:Viral Proteins