In vitro assembly of a prohead-like structure of the Rhodobacter capsulatus gene transfer agent.
The gene transfer agent (GTA) is a phage-like particle capable of exchanging double-stranded DNA fragments between cells of the photosynthetic bacterium Rhodobacter capsulatus. Here we show that the major capsid protein of GTA, expressed in E. coli, can be assembled into prohead-like structures in the presence of calcium ions in vitro. Transmission electron microscopy (TEM) of uranyl acetate staining material and thin sections of glutaraldehyde-fixed material demonstrates that these associates have spherical structures with diameters in the range of 27-35 nm. The analysis of scanning TEM images revealed particles of mass approximately 4.3 MDa, representing 101+/-11 copies of the monomeric subunit. The establishment of this simple and rapid method to form prohead-like particles permits the GTA system to be used for genome manipulation within the photosynthetic bacterium, for specific targeted drug delivery, and for the construction of biologically based distributed autonomous sensors for environmental monitoring.
Spano
Anthony J
AJ
Department of Biology, University of Virginia, Charlottesville, VA 22904, USA. ajs6z@virginia.edu <ajs6z@virginia.edu>
Chen
Frank S
FS
Goodman
Benjamin E
BE
Sabat
Agnes E
AE
Simon
Martha N
MN
Wall
Joseph S
JS
Correia
John J
JJ
McIvor
Wilson
W
Newcomb
William W
WW
Brown
Jay C
JC
Schnur
Joel M
JM
Lebedev
Nikolai
N
D001435:Bacteriophages / Q000235:genetics / Q000648:ultrastructure; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D005814:Genes, Viral; D008854:Microscopy, Electron; D005810:Multigene Family; D016366:Open Reading Frames; D016354:Rhodobacter capsulatus / Q000235:genetics* / Q000648:ultrastructure / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics / Q000302:isolation & purification; D019065:Virus Assembly
D004269:DNA, Bacterial; D004279:DNA, Viral; D014764:Viral Proteins