title: Variation of the permeability of bacteriophage T4: analysis by use of a protein-specific probe for the T4 interior.
abstract: The permeability of bacteriophage T4 and the change in T4 permeability caused by mutation to osmotic shock resistance are investigated here by quantification of the kinetics with which both a DNA-specific probe (ethidium) and a protein-specific probe [1,1'-bi(4-anilino)naphthalene-5,5'-di-sulfonic acid, or bis-ANS)] bind to T4. In the case of an osmotic shock-resistant mutant, T40s41, both ethidium and bis-ANS bind with first order kinetics. The first-order rate constant (k*) for both bis-ANS and ethidium is a function of anion type and concentration. Adenosine triphosphate, phosphate, bisulfite, sulfate, and acetate anions all reduce k* below the k* observed when chloride is the only anion. When chloride is the only anion at 25 degrees C, k* values for binding to T40s41 are orders of magnitude above k* values for binding to wild-type T4 (T4wt). At 25 degrees C, k* for T4wt is too small to measure but k* for T4wt increases at 50-55 degrees C to values approaching those measured for T40s41, without inactivating T4wt, when chloride is the only anion; during heating, T4wt is stabilized by both ethidium and bis-ANS. Binding to T4wt is reversible at 50-55 degrees C, but not at 25 degrees C. Equilibrium binding of bis-ANS to T40s41 reveals 112 +/- 24 sites per T4 capsid. Equilibrium binding of ethidium to T40s41 reveals both high- and low-affinity sites previously observed in the packaged DNA of other bacteriophages. The ATP-induced decrease in k* is not accompanied by a decrease in equilibrium binding. The following hypotheses are presented to explain the above data: (a) All detected bis-ANS binding sites on T4 are interior to the outer surface of T4. (b) The value of k* for both bis-ANS and ethidium is controlled at the port(s) of passage through the outer shell of the T4 capsid. (c) The anions present control k* values at the port(s) of entry, probably by controlling the size of this port. The effects on k* of phosphate explain the otherwise paradoxical observation [P. J. McCall and V. A. Bloomfield (1976) Biopolymers 15, 2323-2336] that in a phosphate buffer the permeabilities of T4wt and T40s41 are the same.
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760.
authors.forename: G A
authors.initials: GA
authors.lastname: Griess
authors.forename: S A
authors.initials: SA
authors.lastname: Khan
authors.forename: P
authors.initials: P
authors.lastname: Serwer
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000838:Anions; D002021:Buffers; D004279:DNA, Viral / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004926:Escherichia coli; D004996:Ethidium / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D007700:Kinetics; D008027:Light; D015335:Molecular Probes / Q000378:metabolism; D009154:Mutation; D010539:Permeability; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013604:T-Phages / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D013696:Temperature
chemical_list: D000817:Anilino Naphthalenesulfonates; D000838:Anions; D002021:Buffers; D004279:DNA, Viral; D005456:Fluorescent Dyes; D015335:Molecular Probes; C035763:5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate); D004996:Ethidium