Two Groups of Capsule-specific Coliphages Coding for RNA Polymerases with New Promoter Specificities

Abstract

SUMMARYFour bacteriophages (A 16, CK235, q~ 1.2 and K31) which specifically attack different encapsulated strains of Escherichia coli have been shown to be related to bacteriophage T7 (which is unable to grow on encapsulated hosts). The conclusion that phages A16 and CK235 are related to T7 is based on (i) similarities in the pattern of expression of intracellular phage proteins, (ii) early appearance, in infected host cells, of a phage DNA-specific RNA polymerase and (iii) hybridization (albeit to a low extent) of A16 DNA and of CK235 DNA to T7 DNA. The first two criteria also apply to phages ~bl. 2 and K31 but hybridization of their DNAs with T7 DNA could not be detected. The RNA polymerases of CK235 and A 16 have similar template specificities and the same applies to the RNA polymerases of ~b 1.2 and K3 i. None of the new RNA polymerases can use T7 DNA as template. INTRODUCTIONEnterobacteria with lipopolysaccharide capsules are lysed by phages which possess specific hydrolases as virion constituents. By means of these particle-bound enzymes the phages tunnel through the thick layer of capsule material until they find the outer membrane where specific adsorption and DNA injection occurs (Lindberg, 1977). One group of such capsule-specific phages is characterized by an icosahedral head with a diameter of about 60 nm, and a short tail of about 20 nm, to which spikes are attached with sixfold symmetry. These spikes display the capsule-lysing activity (Bessler et al., 1975;Rieger-Hug & Stirm, 1981). Since this particle morphology is reminiscent of that of the classical coliphage T7 (which, however, does not infect capsulated strains), Korsten et al. (1979) examined two such capsule-specific phages, Klebsiella phage K11, and Citrobacter phage Villi, with regard to their genetic relatedness to T7; they found that indeed the genome structures of T7, K11 and VilII were similar in various respects. The most striking feature was the synthesis, early in infection by K11, and by VilII, of a phagecoded RNA polymerase which recognizes only DNA of the homologous phage as a template. This observation closely corresponds to what is known for phage T7, and thus it was hypothesized that, in spite of the lack of heterologous transcription (i.e. transcription of the DNA of one phage by the RNA polymerase of another), there was a phylogenetic relationship between T7, K11 and Villi. In the meantime Dietz (1985) and Dietz et al. (1985) have confirmed this hypothesis for T7 and K11 by means of base sequence analysis of some segments of K11 DNA and comparison to the corresponding sequences of T7 DNA, as determined by , and to the DNA sequences of T3 (which is related to T7) as determined by Fujisawa & Sugimoto (1983) and by McAllister et al. (1983). However, so far no capsule-specific Escherichia coli phages have been shown to be related to T7. Considering this, we have investigated a series of phages which specifically lyse one of three different capsule-producing E. coli strains. We did this mainly by (i) comparison, by PAGE and auto...

Information theory based T7-like promoter models: classification of bacteriophages and differential evolution of promoters and their polymerases

“…BA14: the BA14-like phages include three isolates ( 29 , 30 ). Others: the RNAPs of the phages A16 and CK235 show substantial heterologous transcription on each other's DNA, but much lower activity on several other members of this group ( 32 ), so these two phages can be assigned to a separate subgroup. Similarly, the phages φ1.2 and K31 have even stronger heterologous transcription, and <10% activity on other members of this group, so they should also belong to a separate subgroup.…”

“…The Vibrio parahaemolyticus phage VpV262 ( 24 ) and rosephage SIO1 ( 25 ) lack an RNAP gene in their genome, but contain a T7-like head structure module; thus, they have been thought to be members of the T7 supergroup ( 24 ). The Klebsiella phage K11 ( 26 , 27 ), Kluyveraphage Kvp1 ( 28 ), coliphage BA14 ( 29 , 30 ) and several others ( 3 , 31 , 32 ) were clearly shown to be closely related to phage T7, though no complete genome sequences are available for them.…”

Genomic Analysis of Bacteriophages SP6 and K1-5, an Estranged Subgroup of the T7 Supergroup

“…Dietz et al also found two different promoter specificities associated with four capsule-specific coliphages. 66 These phages were not characterized by sequence analysis but two of them hybridized weakly to T7 DNA, and may thus be related to K1-5. It is not obvious how promoter specificities change, although a single amino acid change is sufficient to switch T7 RNAP from T7 to T3 promoter specificity.…”

Biochemistry, Genetics, and Applications of Exopolysaccharide Production in Streptococcus thermophilus: A Review

“…In Vibrio cholera, for example, phages that specifically lyse CPS + strains have been isolated and used to identify variants that lacked CPS (Albert et al, 1996). Specific phages infecting E. coli strains that possess CPS have also been isolated (Dietz et al, 1986;Clarke et al, 2000;Scholl et al, 2001). For other gram-negative bacteria such as Rhizobium meliloti, EPS have been demonstrated to inhibit phage adsorption by coating the cells (Defives et al, 1996).…”