The episodic evolution of fibritin: traces of ancient global environmental alterations may remain in the genomes of T4‐like phages

Abstract

The evolutionary adaptation of bacteriophages to their environment is achieved by alterations of their genomes involving a combination of both point mutations and lateral gene transfer. A phylogenetic analysis of a large set of collar fiber protein (fibritin) loci from diverse T4-like phages indicates that nearly all the modular swapping involving the C-terminal domain of this gene occurred in the distant past and has since ceased. In phage T4, this fibritin domain encodes the sequence that mediates both the attachment of the long tail fibers to the virion and also controls, in an environmentally sensitive way, the phage's ability to infect its host bacteria. Subsequent to its distant period of modular exchange, the evolution of fibritin has proceeded primarily by the slow vertical divergence mechanism. We suggest that ancient and sudden changes in the environment forced the T4-like phages to alter fibritin's mode of action or function. The genome's response to such episodes of rapid environmental change could presumably only be achieved quickly enough by employing the modular evolution mechanism. A phylogenetic analysis of the fibritin locus reveals the possible traces of such events within the T4 superfamily's genomes.

Phages associated with horses provide new insights into the dominance of lateral gene transfer in virulent bacteriophages evolution in natural systems

“…Co-evolution of the phage with the host on the solid medium was followed in the experimental set up described previously (Letarov and Krisch 2013). Briefly, the material from 60 phage G7C plaques obtained on E. coli 4s lawn was transferred to the fresh LB plate.…”

RB49-like Bacteriophages Recognize O Antigens as One of the Alternative Primary Receptors

“…This may indicate that the LTF pre-adsorption conformation in RB49-like phages may differ from phage T4. In phage T4, the fixation of the LTFs in the “up” position is in part dependent on the interaction of the LTF with the collar and whiskers formed by the Wac protein [ 66 , 67 , 68 ]. Noteworthy, the Wac protein of RB49-like phages caries the C-terminal moiety unrelated to that T4 Wac [ 66 , 67 ].…”

Characterization ofErwinia tracheiphilaBacteriophage FBB1 Isolated from Spotted Cucumber Beetles that VectorE. tracheiphila

“…For the short tail fibers, this is the domain involved in host receptor recognition. For fibritin neck whisker proteins, this is the domain that interacts with the tail fibers (Comeau et al 2007;Letarov and Krisch 2013). FBB1 also exhibits polymorphisms at the loci for the long tail fiber protein components; these include the proximal subunit (gp34 homolog), and the hinge connector (gp35 and gp36 homologs) (Figure 7).…”