Genome of Enterobacteriophage Lula/phi80 and insights into its ability to spread in the laboratory environment.

J Bacteriol 2012 Dec 5;194(24):6802-17. Epub 2012 Oct 5.

Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.

The novel temperate bacteriophage Lula, contaminating laboratory Escherichia coli strains, turned out to be the well-known lambdoid phage phi80. Our previous studies revealed that two characteristics of Lula/phi80 facilitate its spread in the laboratory environment: cryptic lysogen productivity and stealthy infectivity. To understand the genetics/genomics behind these traits, we sequenced and annotated the Lula/phi80 genome, encountering an E. coli-toxic gene revealed as a gap in the sequencing contig and analyzing a few genes in more detail. Lula/phi80's genome layout copies that of lambda, yet homology with other lambdoid phages is mostly limited to the capsid genes. Lula/phi80's DNA is resistant to cutting with several restriction enzymes, suggesting DNA modification, but deletion of the phage's damL gene, coding for DNA adenine methylase, did not make DNA cuttable. The damL mutation of Lula/phi80 also did not change the phage titer in lysogen cultures, whereas the host dam mutation did increase it almost 100-fold. Since the high phage titer in cultures of Lula/phi80 lysogens is apparently in response to endogenous DNA damage, we deleted the only Lula/phi80 SOS-controlled gene, dinL. We found that dinL mutant lysogens release fewer phage in response to endogenous DNA damage but are unchanged in their response to external DNA damage. The toxic gene of Lula/phi80, gamL, encodes an inhibitor of the host ATP-dependent exonucleases, RecBCD and SbcCD. Its own antidote, agt, apparently encoding a modifier protein, was found nearby. Interestingly, Lula/phi80 lysogens are recD and sbcCD phenocopies, so GamL and Agt are part of lysogenic conversion.

Download full-text PDF

Source
http://jb.asm.org/cgi/doi/10.1128/JB.01353-12
Publisher Site
http://dx.doi.org/10.1128/JB.01353-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3510586PMC
December 2012
23 Reads

Publication Analysis

Top Keywords

dna damage
12
laboratory environment
8
phage titer
8
endogenous dna
8
response endogenous
8
lula/phi80 lysogens
8
lula/phi80
8
spread laboratory
8
dna
7
inhibitor host
4
cuttable daml
4
layout copies
4
genome layout
4
100-fold high
4
detail lula/phi80's
4
lula/phi80's genome
4
dna cuttable
4
encodes inhibitor
4
gaml encodes
4
lambdoid phages
4

References

(Supplied by CrossRef)
Genetic dissection of the biochemical activities of RecBCD enzyme
Amundsen et al.
Genetics 1990
Derivations and genotypes of some mutant derivatives of Escherichia coli K-12
Bachmann et al.
1987
BRL pUC host: E. coli DH5α competent cells
Bethesda Research Laboratories et al.
Focus 1986
Comparative molecular biology of lamboid phages
Campbell et al.
Annu. Rev. Microbiol. 1994
Working with T4
Carlson et al.
1994
Restriction and modification
Carlson et al.
1994

Similar Publications