Formation of the prohead core of bacteriophage T4 in vivo

Traub, Frank; Maeder, M

doi:10.1128/jvi.49.3.892-901.1984

Cited by 30 publications

(27 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A direct interaction between the portal protein and the scaffold protein was only shown for the B. subtilis phage f29 (Guo et al, 1991). Evidence supporting this type of interaction was also reported in coliphage T4 (Traub and Maeder, 1984) and Salmonella typhimurium phage P22 (Greene and King, 1996).…”

Section: Characterization Of Gp6 Mutants That Block Initial Steps In mentioning

confidence: 67%

The high‐resolution functional map of bacteriophage SPP1 portal protein

Isidro

Santos

Henriques

et al. 2003

Molecular Microbiology

View full text Add to dashboard Cite

SummaryAn essential component in the assembly of nucleocapsids of tailed bacteriophages and of herpes viruses is the portal protein that is located at the unique vertex of the icosahedral capsid through which DNA movements occur. A library of mutations in the bacteriophage SPP1 portal protein (gp6) was generated by random mutagenesis of gene 6 . Screening of the library allowed identification of 67 single amino acid substitutions that impair portal protein function. Most of the mutations cluster within stretches of a few amino acids in the gp6 carboxyl-terminus. The mutations were divided into five classes according to the step of virus assembly that they impair: (1) production of stable gp6; (2) interaction of gp6 with the minor capsid protein gp7; (3) incorporation of gp6 in the procapsid structure; (4) DNA packaging; and (5) sizing of the packaged DNA molecule. Most of the mutations fell in classes 3 and 4. This is the first high-resolution functional map of a portal protein, in which its function at different steps of viral assembly can be directly correlated with specific regions of its sequence. The work provides a framework for the understanding of central processes in the assembly of viruses that use specialized portals to govern entry and exit of DNA from the viral capsid.

show abstract

Section: Characterization Of Gp6 Mutants That Block Initial Steps In mentioning

confidence: 67%

The high‐resolution functional map of bacteriophage SPP1 portal protein

Isidro

Santos

Henriques

et al. 2003

Molecular Microbiology

View full text Add to dashboard Cite

show abstract

“…Different mutants in gene 23, of which the product is the main component of the shell, were used for studying the action of its gene product. With am mutants in gene 23, no particles are produced at all, except a few 'naked' scaffolding cores [22]. A ts mutant leads to abnormal ('crummy') proheads which no longer mature [23].…”

Section: The Experimental Systemsmentioning

confidence: 99%

“…Nuked scufiolding cores of T4 compared with proheads. (a, b) Electron micrographs of thin sections of mutant-infected E. toli cells [22]. In (b) typical proheads attached to the plasma membrane can be seen.…”

Section: In Vitro Assembliesmentioning

confidence: 99%

“…In phage P22 the in vitro assembly of proheads seems to proceed like copolymerisation of scaffold and shell proteins [60]. For T,,,,, the fact that scaffolds can be observed 'naked' in vivo [22] and produced in vitro without the coat protein [42] has given rise to the hypothesis that scaffolding cores might act as precursors for proheads. On the one hand, some in vivo experimental results can be interpreted in this way [61].…”

Section: Additional Studies On the Form Determination With Other Phagesmentioning

confidence: 99%

See 1 more Smart Citation

Form determination of the heads of bacteriophages

Kellenberger

1990

European Journal of Biochemistry

View full text Add to dashboard Cite

The shape of the DNA-containing heads of many bacteriophages is not only determined by the properties of the protein subunits which build the shell (capsid) but also by the scaffolding core which is a transient structure of the prohead. The form-determining properties of the scaffolding proteins have been characterized by genetic methods based on conditional mutants and site-directed mutagenesis. The mechanism of form determination has been studied by in vitro assembly experiments. The theoretical background is discussed and different models for mechanisms of form determination are considered. Definitive decisions about the validity of a model is still limited by the difficulty of obtaining unambiguous answers on the stoichiometry and the fine structure of the scaffold because of their high instability.The conservation of the specific shape of any living species is the very basic observation that gave rise to the notion of genetics. The mechanisms which underlay form determination still remain among the fundamental unsolved problems of biology although the descriptive part, the genesis of shape (morphogenesis) from the fertilized egg to the fully grown organism, is known in detail for most multicellular organisms. In recent decades one has also learned that the different steps of the morphogenesis of multicellular organisms must be determined through the successive switching on and off of groups of genes. In consequence, toddy's research efforts are concentrated on the mechanisms of the genetic control of gene expression. Only once these are understood and the newly expressed genes identified, can the functions of the corresponding gene products, the proteins, be studied. The phenomena of cellular recognition and of contact inhibition of growth must be understood before one is even able to formulate plausible hypotheses for the form determination of multicellular organs and organisms. How, for example, does a regenerating, partly ectomized liver, know how to stop cellular proliferation when the correct shape is again achieved?The situation is much better, although quite different, for multi-molecular structures represented by elements of the cytoskeleton or by other cellular organelles and, above all, by viruses [l -31.Everybody is more or less familiar with what is called selfassembly of a multimolecular structure. It is represented, for instance, by some cases of virus capsids, where the shape and binding properties of the protein subunit are such that they can assemble only into one type of hollow sphere. Such cases are considered as form determination of the first order. This situation is somewhat trivial; indeed, for the large majority of viruses, form determination is not so simple: inner scaffolds are transiently needed to help in imposing any form to the capsid. The form of the capsid is therefore determined by the information contributed by both the properties of the subunitsCorrespondence to E. Kellcnberger, Department of Microbiology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Bas...

show abstract

“…Only the internal proteins (IPI, IPII, and IPIII) are found in comparable amounts in the prohead and in their processed form (IP*) in the phage. We have previously shown the formation of naked scaffolding cores in vivo when shell proteins are absent (17,18). These naked cores consisted of the T4 internal head proteins and were morphologically similar to cores found in the prohead, i.e., they had a prolate shape and a defined size.…”

mentioning

confidence: 99%

Prohead core of bacteriophage T4 can act as an intermediate in the T4 head assembly pathway

Kühn¹,

Keller²,

Maeder³

et al. 1987

J Virol

Self Cite

View full text Add to dashboard Cite

Bacteriophage T4 assembly was impaired in Escherichia coli hdB3-1 at an incubation temperature below 30°C. Naked probead cores (head scaffold) bound to the inner surface of the plasma membrane accumulated, and the major shell protein (gp23) precipitated into visible intracellular aggregates in the cytoplasm. Shifting the temperature to 429C allowed newly synthesized gp23 to assemble around the accumulated cores. We conclude that synchronous assembly of the scaffold and shell is not obligatory and that naked cores can serve as intermediates in the T4 assembly pathway.

show abstract

Formation of the prohead core of bacteriophage T4 in vivo

Cited by 30 publications

References 53 publications

The high‐resolution functional map of bacteriophage SPP1 portal protein

The high‐resolution functional map of bacteriophage SPP1 portal protein

Form determination of the heads of bacteriophages

Prohead core of bacteriophage T4 can act as an intermediate in the T4 head assembly pathway

Contact Info

Product

Resources

About