Internal DNA pressure modifies stability of WT phage

dsDNA in bacteriophages is highly stressed and exerts internal pressures of many atmospheres (1 atm = 101.3 kPa) on the capsid walls. We investigate the correlation between packaged DNA length in λ phage (78–100% of WT DNA) and capsid strength by using an atomic force microscope indentation technique. We show that phages with WT DNA are twice as strong as shorter genome mutants, which behave like empty capsids, regardless of high internal pressure. Our analytical model of DNA-filled capsid deformation shows that, because of DNA-hydrating water molecules, an osmotic pressure exists inside capsids that increases exponentially when the packaged DNA density is close to WT phage. This osmotic pressure raises the WT capsid strength and is approximately equal to the maximum breaking force of empty shells. This result suggests that the strength of the shells limits the maximal packaged genome length. Moreover, it implies an evolutionary optimization of WT phages allowing them to survive greater external mechanical stresses in nature.

[1]  W. Gelbart,et al.  Osmotic shock and the strength of viral capsids. , 2003, Biophysical journal.

[2]  Sherwood R. Casjens,et al.  DNA packaging by the double-stranded DNA bacteriophages , 1980, Cell.

[3]  David Reguera,et al.  Mechanical properties of viral capsids. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[4]  J. Sambrook,et al.  Molecular Cloning: A Laboratory Manual , 2001 .

[5]  Julio Gómez-Herrero,et al.  Jumping mode scanning force microscopy , 1998 .

[6]  L. Randall-Hazelbauer,et al.  Isolation of the Bacteriophage Lambda Receptor from Escherichia coli , 1973, Journal of bacteriology.

[7]  S. Timoshenko,et al.  Theory of elasticity , 1975 .

[8]  B. Lee,et al.  Measurement of the repulsive force between polyelectrolyte molecules in ionic solution: hydration forces between parallel DNA double helices. , 1984, Proceedings of the National Academy of Sciences of the United States of America.

[9]  William M. Gelbart,et al.  Osmotic pressure inhibition of DNA ejection from phage , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[10]  Rob Phillips,et al.  Mechanics of DNA packaging in viruses , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[11]  S. Harrison,et al.  DNA arrangement in isometric phage heads , 1977, Nature.

[12]  William M. Gelbart,et al.  DNA packaging and ejection forces in bacteriophage , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Paul Grayson,et al.  The effect of genome length on ejection forces in bacteriophage lambda. , 2005, Virology.

[14]  L. Enquist,et al.  Experiments With Gene Fusions , 1984 .

[15]  Prashant K. Purohit,et al.  Force steps during viral DNA packaging , 2003, q-bio/0309010.

[16]  T. Dokland,et al.  Structural transitions during maturation of bacteriophage lambda capsids. , 1993, Journal of molecular biology.

[17]  V. Parsegian,et al.  Osmotic stress for the direct measurement of intermolecular forces. , 1986, Methods in enzymology.

[18]  Carlos Bustamante,et al.  Supplemental data for : The Bacteriophage ø 29 Portal Motor can Package DNA Against a Large Internal Force , 2001 .

[19]  W S Klug,et al.  Nanoindentation studies of full and empty viral capsids and the effects of capsid protein mutations on elasticity and strength. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[20]  Martin Phillips,et al.  Measurements of DNA lengths remaining in a viral capsid after osmotically suppressed partial ejection. , 2005, Biophysical journal.

[21]  M. Feiss,et al.  Packaging of the bacteriophage λ chromosome: Effect of chromosome length , 1977 .

[22]  A. Graff,et al.  Virus-assisted loading of polymer nanocontainer , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[23]  V. Parsegian,et al.  Direct measurement of temperature-dependent solvation forces between DNA double helices. , 1992, Biophysical journal.

[24]  A. Evilevitch,et al.  Measuring the Force Ejecting DNA from Phage , 2004 .

[25]  H. Sambrook Molecular cloning : a laboratory manual. Cold Spring Harbor, NY , 1989 .

[26]  A. Wlodawer,et al.  Novel fold and capsid-binding properties of the λ-phage display platform protein gpD , 2000, Nature Structural Biology.

[27]  A. D. Hershey,et al.  The Bacteriophage Lambda. , 1971 .

[28]  J. Sader,et al.  Calibration of rectangular atomic force microscope cantilevers , 1999 .

[29]  D. Scandella,et al.  Multiple steps during the interaction between coliphage lambda and its receptor protein in vitro. , 1976, Virology.

[30]  William M Gelbart,et al.  Forces and pressures in DNA packaging and release from viral capsids. , 2003, Biophysical journal.

[31]  A. Evilevitch,et al.  Forces controlling the rate of DNA ejection from phage lambda. , 2007, Journal of molecular biology.

[32]  M. Roa Receptor‐triggered ejection of DNA and protein in phage lambda , 1981 .

[33]  L. Tsui,et al.  Role of the host in virus assembly: cloning of the Escherichia coli groE gene and identification of its protein product. , 1978, Proceedings of the National Academy of Sciences of the United States of America.

[34]  Rob Phillips,et al.  Forces during bacteriophage DNA packaging and ejection. , 2004, Biophysical journal.

[35]  J. King,et al.  The structural organization of DNA packaged within the heads of T4 wild-type, isometric and giant bacteriophages , 1978, Cell.

[36]  G. Wuite,et al.  Bacteriophage capsids: tough nanoshells with complex elastic properties. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[37]  Viola Vogel,et al.  Bacterial Adhesion to Target Cells Enhanced by Shear Force , 2002, Cell.