Heat induced capsid disassembly and DNA release of bacteriophage λ.
Successive structural changes of bacteriophage λ upon heating were characterized with quantitative experimental methods. In the commonly used Tris-Mg buffer, differential scanning calorimetry measurements first established that the protein capsid of λ phage melts at 87 °C and its genomic DNA melts at 91 °C. Interestingly, prior to the capsid melting, λDNA was found to escape out of the capsid and subject to DNase digestion above ~68 °C, as concluded from light scattering, UV absorption, and electron microscopy studies. Further investigations indicated distinct temperature-dependent behaviors of the three phage proteins. Around 68 °C, disruption of the tail first occurs and leads to the escape of λ DNA; above the capsid melting temperature of 87 °C, the auxiliary protein gpD of the phage head remains soluble in solution and resists centrifugal sedimentation, whereas the major capsid protein gpE is easily precipitated and likely exists as aggregates.
Department of Physics, George Washington University, Washington, DC, United States of America. xqiu@gwu.edu
Xiangyun
X
Qiu
D010582:Bacteriophage lambda / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002021:Buffers; D002152:Calorimetry, Differential Scanning; D002213:Capsid / Q000737:chemistry* / Q000378:metabolism; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004279:DNA, Viral / Q000737:chemistry*; D003850:Deoxyribonuclease I / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008027:Light; D008854:Microscopy, Electron; D009691:Nucleic Acid Denaturation; D011487:Protein Conformation; D012542:Scattering, Radiation
D002021:Buffers; D036022:Capsid Proteins; D004279:DNA, Viral; D006023:Glycoproteins; C406073:gpD protein, lambda phage; D003850:Deoxyribonuclease I