Introns and intein coding sequence in the ribonucleotide reductase genes of Bacillus subtilis temperate bacteriophage SPβ

Abstract

The two putative ribonucleotide reductase subunits of the Bacillus subtilis bacteriophage SP␤ are encoded by the bnrdE and bnrdF genes that are highly similar to corresponding host paralogs, located on the opposite replication arm. In contrast to their bacterial counterparts, bnrdE and bnrdF each are interrupted by a group I intron, efficiently removed in vivo by mRNA processing. The bnrdF intron contains an ORF encoding a polypeptide similar to homing endonucleases responsible for intron mobility, whereas the bnrdE intron has no obvious trace of coding sequence. The downstream bnrdE exon harbors an intervening sequence not excised at the level of the primary transcript, which encodes an in-frame polypeptide displaying all the features of an intein. Presently, this is the only intein identified in bacteriophages. In addition, bnrdE provides an example of a group I intron and an intein coding sequence within the same gene.

Romulus and Remus, Two Phage Isolates Representing a Distinct Clade within the Twortlikevirus Genus, Display Suitable Properties for Phage Therapy Applications

“…Phages Sb-1, ISP, Staph1N, Fi200W, P4W, 676Z, A3R, MSA6, and A5-W display an intron distribution similar to those of K and G1 (13), whereas phage GH15 lacks all previously described introns (15). Although splicing in phages was first believed to be a regulatory mechanism of DNA metabolism (22,23), the discovery of introns in late genes (8,21,24) challenges the relevance of this hypothesis. So far, no other solid prediction of the meaning of splicing in phages can be made.…”

Inhibitory effect of prophage SP.BETA. fragments on phage SP10 ribonucleotide reductase function and its multiplication in Bacillus subtilis

“…4A). The bnrdE gene possesses intron and intein and is subjected to posttranscriptional modification to generate the mature form of RRase (Lazarevic et al, 1998). Therefore the nucleotide sequences of the bnrdE gene separated by intron and intein were connected by means of PCR and the resultant DNA fragment was cloned under the control of Pxyl for the analysis of SP10 susceptibility.…”

“…The bnrdE and bnrdF genes of SPβ encode the putative ribonucleotide reductase (RRase) subunits alpha and beta, respectively, that are highly similar to corresponding host homologs encoded by the nrdE and nrdF genes (Scotti et al, 1996, Lazarevic et al, 1998. RRase is an essential enzyme involved in the biosynthesis of deoxyribonucleotides from the corresponding ribonucleotides.…”

“…B) Semi-quantitative PCR was performed with 10 ng of total DNA of samples using the host-specific primer pair (nrdE; 1 to 6 lanes on the left) and the phage-specific primer pair (xnrdE; 1 to 6 lanes on the right). endonuclease encoded by yosQ (Lazarevic et al, 1998) (Fig. 3).…”

“…This 135 kb long region contains of 187 putative ORFs. Previous studies of SPβ led to the identification of the genes involved in DNA methylation (Trautner et al, 1980), control of phage lysogeny, immunity to cognate SPβ (McLaughlin et al, 1986), endolysin production (Regamey and Karamata, 1998) and DNA metabolism (Lazarevic et al, 1998). However, the function of almost all other genes in SPβ is unknown.…”