Biomaterial Database

The interaction of DNA with bacteriophage phi 29 connector: a study by AFM and TEM. 1996

M Valle, and J M Valpuesta, and J L Carrascosa, and J Tamayo, and R Garcia

Centro Nacional de Biotecnología, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Spain.

The connector of bacteriophage phi 29 is involved in DNA packaging during viral morphogenesis and we have studied its in vitro binding to DNA using either linear or circular DNA. The protein-DNA complexes have been analyzed by transmission electron microscopy (TEM) and by atomic force microscopy (AFM) of samples directly deposited on mica. TEM showed the presence of a specific binding due to the interaction of the protein with the free ends of the DNA. The study of these samples by AFM showed two major types of morphologies: The interaction of the connector with circular DNA revealed that the strands of DNA that enter and exit the protein complex form an angle with a mean value of 132 degrees. Nevertheless, when the connector was incubated with linear DNA (and later circularized), there was an additional bend angle of about 168 degrees. Further morphological analysis of the latter samples by AFM revealed a structure of the protein-DNA complex consistent with the DNA traversing the connector, probably through the inner channel. On the other hand, images from the samples obtained by incubation of the connector with circular DNa were consistent with an interaction of the DNA with the outer side of the connector.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002213	Capsid	The outer protein protective shell of a virus, which protects the viral nucleic acid. Capsids are composed of repeating units (capsomers or capsomeres) of CAPSID PROTEINS which when assembled together form either an icosahedral or helical shape.	Procapsid,Prohead,Capsids,Procapsids,Proheads
D004270	DNA, Circular	Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)	Circular DNA,Circular DNAs,DNAs, Circular
D004279	DNA, Viral	Deoxyribonucleic acid that makes up the genetic material of viruses.	Viral DNA
D017103	Bacillus Phages	Viruses whose host is Bacillus. Frequently encountered Bacillus phages include bacteriophage phi 29 and bacteriophage phi 105.	Bacteriophage phi 105,Bacteriophage phi 29,Phage phi 105,Phage phi 29,Bacillus Bacteriophages,Bacillus Bacteriophage,Bacillus Phage,Bacteriophage, Bacillus,Bacteriophages, Bacillus
D018625	Microscopy, Atomic Force	A type of scanning probe microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. These deflections produce a topographic map of the sample.	Atomic Force Microscopy,Force Microscopy,Scanning Force Microscopy,Atomic Force Microscopies,Force Microscopies,Force Microscopies, Scanning,Force Microscopy, Scanning,Microscopies, Atomic Force,Microscopies, Force,Microscopies, Scanning Force,Microscopy, Force,Microscopy, Scanning Force,Scanning Force Microscopies
D036022	Capsid Proteins	Proteins that form the CAPSID of VIRUSES.	Procapsid Protein,Procapsid Proteins,Viral Coat Protein,Viral Coat Proteins,Viral V Antigens,Viral V Proteins,Capsid Protein,Viral Outer Coat Protein,Antigens, Viral V,Coat Protein, Viral,V Antigens, Viral,V Proteins, Viral