The P2 phage old gene: sequence, transcription and translational control

The old (overcoming lysogenization defect) gene product of bacteriophage P2 kills Escherichia coli recB and recC mutants and interferes with phage [lambda] growth [ Sironi et al., Virology 46 (1971) 387-396 ; Lindahl et al., Proc. Natl. Acad. Sci. USA 66 (1970) 587-594]. Specialized transducing [lambda] phages, which lack the recombination region, can be selected by plating [lambda] stocks on E. coli that carry the old gene on a prophage or plasmid [Finkel et al., Gene 46 (1986) 65-69]. Deletion and sequence analyses indicate that the old-encoded protein has an Mr of 65 373 and that its transcription is leftward. Primer extension analyses locate the transcription start point near the right end of the virion DNA. A bacterial mutant, named pin3 and able to suppress the effects of the old gene, has been isolated [Ghisotti et al., J. Virol. 48 (1983) 616-626]. In a pin3 mutant strain, carrying the old gene on a prophage or plasmid, the amount of old transcript is greatly reduced. The effect of the pin3 mutation is abolished by the wild-type allele of argU, an arginine tRNA that reads the rare Arg codons AGA and AGG, which are used for eight of the 14 Arg codons in the old gene. Thus the pin3 allele probably stalls translation of the old mRNA, causing this mRNA to be degraded. Isoelectric focusing and electrophoretic analysis identify the old gene product as a basic protein of approx. 65 kDa.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27631/1/0000007.pd

Bacteriophage Protein-Protein Interactions

Bacteriophages T7, λ, P22, and P2/P4 (from Escherichia coli), as well as φ29 (from Bacillus subtilis), are among the best-studied bacterial viruses. This chapter summarizes published protein interaction data of intraviral protein interactions, as well as known phage-host protein interactions of these phages retrieved from the literature. We also review the published results of comprehensive protein interaction analyses of Pneumococcus phages Dp-1 and Cp-1, as well as coliphages λ and T7. For example, the ≈ 55 proteins encoded by the T7 genome are connected by ≈ 43 interactions with another ≈ 15 between the phage and its host. The chapter compiles published interactions for the well-studied phages λ (33 intra-phage/22 phage-host), P22 (38/9), P2/P4 (14/3), and φ29 (20/2). We discuss whether different interaction patterns reflect different phage lifestyles or whether they may be artifacts of sampling. Phages that infect the same host can interact with different host target proteins, as exemplified by E. coli phage λ and T7. Despite decades of intensive investigation, only a fraction of these phage interactomes are known. Technical limitations and a lack of depth in many studies explain the gaps in our knowledge. Strategies to complete current interactome maps are described. Although limited space precludes detailed overviews of phage molecular biology, this compilation will allow future studies to put interaction data into the context of phage biology. © 2012 Elsevier Inc.European Union ( HEALTH-F3-2009-223101); Spanish Ministry of Science and Innovation (BFU2008-00215)Peer Reviewe

Structural insight into DNA binding and oligomerization of the multifunctional Cox protein of bacteriophage P2

The Cox protein from bacteriophage P2 is a small multifunctional DNA-binding protein. It is involved in site-specific recombination leading to P2 prophage excision and functions as a transcriptional repressor of the P2 Pc promoter. Furthermore, it transcriptionally activates the unrelated, defective prophage P4 that depends on phage P2 late gene products for lytic growth. In this article, we have investigated the structural determinants to understand how P2 Cox performs these different functions. We have solved the structure of P2 Cox to 2.4 angstrom resolution. Interestingly, P2 Cox crystallized in a continuous oligomeric spiral with its DNA-binding helix and wing positioned outwards. The extended C-terminal part of P2 Cox is largely responsible for the oligomerization in the structure. The spacing between the repeating DNA-binding elements along the helical P2 Cox filament is consistent with DNA binding along the filament. Functional analyses of alanine mutants in P2 Cox argue for the importance of key residues for protein function. We here present the first structure from the Cox protein family and, together with previous biochemical observations, propose that P2 Cox achieves its various functions by specific binding of DNA while wrapping the DNA around its helical oligomer.AuthorCount:9;</p