Bacteriophage infection interferes with guanosine 3'-diphosphate-5'-diphosphate accumulation induced by energy and nitrogen starvation in the cyanobacterium Anacystis nidulans

Abstract

Anacystis nidulans accumulates large amounts of guanosine 3'-diphosphate-5'-diphosphate (ppGpp) upon nutritional or energy starvation induced by lightto-dark shift, treatment with carbonylcyanide-m-chlorophenylhydrazone (an uncoupler), or treatment with L-methionine-DL-sulfoximine (an inducer of nitrogen starvation). In contrast to healthy A. nidulans cells, those infected by AS-1 cyanophage do not respond with ppGpp accumulation when starved after about one-third of the complete infection cycle, except, to some extent, under extreme conditions when both nitrogen deprivation and energy deprivation are induced simultaneously (darkening plus L-methionime-DL-sulfoximine treatment). In contrast to cyanophage infection in Anacystis, infection with T4 phage of Escherichia coli CP 78 cells does not affect their accumulation of ppGpp under treatments identical with or similar to those applied in the experiments with Anacystis. This difference in response of phage-infected heterotrophic and photoautotrophic cells to starvation seems to reflect differences in control of nutritional or energy metabolism rather than differences in ability to synthesize ppGpp.

Cyanophage MazG is a pyrophosphohydrolase but unable to hydrolyse magic spot nucleotides

“…Although, the presence and identity of AMGs in bacteriophage genomes is widely appreciated (Millard et al, ; Sullivan et al, ; Crummett et al ., 2016) the specific role of many of these genes has not been resolved. Here, we sought to elucidate the activity of the cyanophage MazG protein given its hypothesized role as a more general modulator of the host stringent response, and with previous data suggesting cyanophage can modulate intracellular levels of (p)ppGpp in infected freshwater cyanobacteria (Borbély et al, ).…”

Host-hijacking and planktonic piracy: how phages command the microbial high seas

“…; Nostoc spp. Non-infective ‘prophages’ (x 3; non-reversible excision)Recombinases (prophage-encoded) act to excise prophages from 3 host genes that are involved in nitrogen fixation ( nifD ; fdxN ; hupL )(O) In low nitrogen environments, excision of prophages from host N-fixation genes enables conversion of host cell to form nitrogen-fixing heterocysts[74] Synechococcus elongatus Cyanophage AS-1Prevents normal ppGpp accumulation under nutrient limitation, and the corresponding expression of genes for starvation survival(O) Inhibits the host’s natural starvation response under nutrient limitation; (P) promotes metabolic activity otherwise undertaken only when food is plentiful, facilitating phage production in low nutrient conditions[14, 114]Abbreviations not used in the main text: ORF Open Reading Frame, dut Deoxyuridine triphophatase, radA DNA recombination protein, pseI Pseudaminic synthase, 2OG 2-oxoglutarate; 2OG-FeII oxygenase Fe (II)-dependent oxygenase superfamily, tctA Tripartite tricarboxylate transporter, GTA Gene Transfer Agents…”

Marine cyanophages and light

“…Guanosine 3′,5′ bispyrophosphate, also known as ppGpp or magic spot, is a global regulator of gene expression in bacteria, but is increasingly recognized now to be centrally involved in the adaptation to a very wide range of environmental stresses (for recent reviews see Magnusson et al ., 2005; Braeken et al ., 2006). Freshwater cyanobacteria have been shown to produce ppGpp in response to changes in their light environment (Mann et al ., 1975) and this accumulation was prevented by phage infection (Borbély et al ., 1980). Analysis of the genome of the marine cyanomyovirus S‐PM2 revealed it to encode an open reading frame encoding a protein with a MazG nucleotide pyrophosphohydrolase domain (Mann et al ., 2005) and homologues are present in the genomes of two cyanomyoviruses infecting Prochlorococcus strains (Sullivan et al ., 2005).…”