PubMed Health⌕ Search

PubMed · 16452449

Identification of a gene encoding a functional reverse transcriptase within a highly variable locus in the P2-like coliphages.

Abstract

The P2-like coliphages are highly similar; the structural genes show at least 96% identity. However, at two loci they have genes believed to be horizontally transferred. We show that the genetic content at the second loci, the TO region, contains six completely different sequences with high AT contents and with different open reading frames. The product of one of them exhibits reverse transcriptase activity and blocks infection of phage T5.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Richard Odegrip, Anders S Nilsson, Elisabeth Haggård-Ljungquist. 2006. Identification of a gene encoding a functional reverse transcriptase within a highly variable locus in the P2-like coliphages.. https://doi.org/10.1128/jb.188.4.1643-1647.2006

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Assembly of bacteriophage P2 and P4 procapsids with internal scaffolding protein.

Assembly of the E. coli bacteriophage P2 into an icosahedral capsid with T = 7 symmetry is dependent on the gpN capsid protein, the gpQ connector protein and the gpO internal scaffolding protein. In the presence of the P4-encoded protein Sid, the same proteins are assembled into a smaller capsid with T = 4 symmetry. Although gpO has long been expected to act as an internal scaffolding protein, it has not been possible to produce P2 procapsids efficiently in vitro or in vivo due to a failure to express gpO at high levels. In this study, we find that full-length gpO undergoes proteolytic degradation within 1 h of induction of expression. However, a truncated version of gpO lacking the N-terminal 25 amino acids (Odelta25) is stably expressed at high levels and is able to direct the formation of P2 size procapsids. In the presence of Sid, Odelta25 is incorporated into P4 procapsids, showing that Sid overrides the effect of gpO on capsid size determination.

Bacteriophage P2↗

Cooperative interactions between bacteriophage P2 integrase and its accessory factors IHF and Cox.

Bacteriophage P2 integrase (Int) mediates site-specific recombination leading to integration or excision of the phage genome in or out of the bacterial chromosome. Int belongs to the large family of tyrosine recombinases that have two different DNA recognition motifs binding to the arm and core sites, respectively, which are located within the phage attachment sites (attP). In addition to the P2 integrase, the accessory proteins Escherichia coli IHF and P2 Cox are needed for recombination. IHF is a structural protein needed for integration and excision by bending the DNA. As opposed to lambda, only one IHF site is found in P2 attP. P2 Cox controls the direction of recombination by inhibiting integration but being required for excision. In this work, the effects of accessory proteins on the capacity of Int to bind to its DNA recognition sequences are analyzed using electromobility shifts. P2 Int binds with low affinity to the arm site, and this binding is greatly enhanced by IHF. The arm binding domain of Int is located at the N-terminus. P2 Int binds with high affinity to the core site, and this binding is also enhanced by IHF. The fact that the cooperative binding of Int and IHF is strongly reduced by lengthening the distance between the IHF and core binding sites indicates that the distance between these sites may be important for cooperative binding. The Int and Cox proteins also bind cooperatively to attP.

Bacteriophage P2↗

Identification of a P2-related prophage remnant locus of Photorhabdus luminescens encoding an R-type phage tail-like particle.

Analysis of the Photorhabdus luminescens genome sequence revealed that the pts region is related to the tail synthesis gene core of the P2 phage. The pts locus encodes a DNA invertase homologue. PCR-RFLP analysis showed the two potential tail fiber regions of the pts locus present DNA inversions. Electron microscopy revealed a phage tail-like particle, related to the R-type family and named R-photorhabdicin, in the culture supernatant of P. luminescens. Mass spectrometry analysis of two sub-units of R-photorhabdicin revealed that they are encoded by the pts locus. The role of this P2-related prophage remnant in the Photorhabdus genome is discussed.

Bacteriophage P2↗