Interruption-deficient mutants of bacteriophage T5. II. Properties of a mutant lacking a specific interruption

A new class of bacteriophage was characterized in purified T5 stocks. Regardless of the host cell, these phages were irreversibly blocked at the first-step-transfer stage under conditions in which whole DNA injection normally takes place. However, they expressed their first-step-transfer functions. These observations confirmed the previously established heterogeneity of T5 bacteriophage populations and provided a new way to define a phage function necessary to release the blocking of T5 DNA injection at the first-step-transfer stage.

Section: Discussionmentioning

confidence: 99%

Evidence for heterogeneity in populations of T5 bacteriophage. II. Some particles are unable to inject their second-step-transfer DNA

Hulen¹,

Labedan²,

Legault-Démare³

1980

“…The present report describes the general properties of interruption-deficient mutants of T5 and the methods used for their isolation. The accompanying paper (21) describes the properties of a mutant that specifically lacks the interruption located at 8% from the left end of T5…”

mentioning

confidence: 99%

Interruption-deficient mutants of bacteriophage T5 I. Isolation and general properties

Rogers¹,

Godwin²,

Shinosky³

et al. 1979

Self Cite

Mutants of bacteriophage T5 were isolated which lack one or more of the natural single-chain interruptions that occur in the mature DNA of this virus. Interruption-deficient mutants were detected by screening survivors of hydroxylamine mutagenesis for altered DNA structure by electrophoresis in agarose slab gels. Over 60 independent mutants were isolated from a survey of approximately 800 phage particles. All of the mutants were viable and could be grouped into two classes. Mutants in one class lacked one of the localized sites where interruptions occur in T5 DNA. To date, mutants that affect five different sites have been obtained. Mutants in the other class were essentially free from interruptions or had a reduced frequency of interruptions throughout the genome. The members of this class included several amber mutants. Complementation tests indicated that at least two genes are required for the presence of interruptions in mature T5 DNA.

“…The single-chain fragments that are relevant for this study are labeled with numbers at the bottom of the figure. Maps that show additional interruptions within the terminal repetitions have been given previously (11,15). The locations of the fragments labeled with arrowheads in lanes 2, 4, and 6 of Fig.…”

Section: Discussionmentioning

confidence: 85%

Interruption-deficient mutants of bacteriophage T5: analysis of single-site mutants

Rhoades¹

1986

Self Cite

The properties of viable mutants of bacteriophage T5 that lack, singly, each of the four major sites at which single-chain interruptions normally occur in T5 DNA are described. The mutations responsible for loss of each interruption were mapped by analysis with HhaI, a restriction endonuclease with a cleavage site (pGCGC) that occurs at the 5' termini of the major interruptions (B. P. Nichols and J. E. Donelson, J. Virol. 22:520-526, 1977). For each mutant tested, loss of a specific interruption resulted in loss of a specific HhaI cleavage site. Multiple single-site mutants were constructed to determine the effect of loss of more than one interruption on phage viability. These recombinants, including a phage that lacks the four major interruptible sites, were fully viable and did not exhibit a compensating increase in the frequency of minor interruptions. The effect of loss of a specific interruption on genetic recombination was tested in two-factor crosses with markers that occur close to, but on opposite sites of, the interruption. Loss of the interruptible site did not affect recombination frequency.