Head maturation pathway of bacteriophages T4 and T2. V. Maturable epsilon-particle accumulating an acridine-treated bacteriophage T4-infected cells

Abstract

A maturable head-related particle of bacteriophage T4 has been identified and characterized. This e-particle has the same size as the prehead, but its shell is made of the cleaved product of gene 23 (gp23*). It contains internal matter, most likely the processed core proteins, which is lost or modified by experimental manipulation. It accumulates, together with partially filled ("grizzled") heads, in T4-infected cells that are treated with 9-aminoacridine. On sections of "wellpreserved" cells the E-particles are not identifiable with certainty; a more or less empty breakdown product of them becomes visible when cytoplasmic leakage is induced. The number of particles per cell is then in agreement with the biochemically determined amount of gp23* and with the number of particles counted in lysates. Morphologically and biochemically, the isolated e-particles closely resemble the empty small particles of 17--infected cells described in previous papers of this series. Both are composed of gp23* and are still unexpanded, so that they are not yet able to bind the minor head proteins soc and hoc. We discuss the possibility of the e-particle being an intermediate on the normal T4 wild-type head maturation pathway.The DNA-containing head of bacteriophage T4 appears to mature out of a proteinous prehead (1,2,23,38). Maturation involves the following events: (i) processing of the shell proteins (gp23, gp24) and of the core proteins (gp22 and internal proteins); (ii) expansion by 15% in linear dimensions; and (iii) packaging of DNA. It is not

Extensive proteolysis of head and inner body proteins by a morphogenetic protease in the giant Pseudomonas aeruginosa phage φKZ

“…Upon phage infection these proteins [the internal proteins (IPs), IPI, IPII, IPIII and Alt] are injected into the host together with the DNA (Black et al ., 1993). Addition of the phage T4 terminase inhibitor 9‐aminoacridine (9AA) to infected bacteria blocks DNA packaging and leads to the accumulation of fully processed mature T4 proheads that contain the cleaved IPs but lack DNA (Schaerli and Kellenberger, 1980).…”

“…Treatment of φKZ with the T4 terminase inhibitor 9AA was generally as described for T4 (Schaerli and Kellenberger, 1980), with the exception that preliminary experiments were undertaken to determine the concentration of 9AA required to inhibit phage particle production (15 µg ml −1 ); the concentration that was subsequently used was 10‐fold higher than required for the same effect on T4. This can be attributed, in part, to the higher tolerance of P. aeruginosa to 9AA than E. coli (Wainwright et al ., 1997) .…”

Multi-Enzyme Assembly on T4 Phage Scaffold

“…This purified material migrated slower on SDS-PAGE gel since the enzyme–Hoc was 40 kDa larger than enzyme–SC ( Figure S3 ). Tailless ΔHoc T4 capsids were produced from ΔHoc T4 phage with a yield of 1–3 mg/L in the presence of 9-aminoacridine, which blocks genomic DNA packaged into the capsids and thus results in no tail attachment to the capsids (Schaerli and Kellenberger, 1980 ). They show faster electrophoretic mobility than WT T4 capsids as indicated in Figure 1C (lanes 4 vs. 6).…”

States of phage T3/T7 capsids: buoyant density centrifugation and cryo-EM

“…A second lesson is that ipDNA-containing capsids are detectable by EM of thin sections. In a study of phage T4, ipDNA-containing capsids are observed as the Bgrizzled^particles of Schaerli and Kellenberger (1980), for example. These particles appear to be intermediates of DNA packaging and are potential targets of future, more advanced studies.…”