PMID:25289638

Citation	Njimona, I, Yang, R and Lamparter, T (2014) Temperature effects on bacterial phytochrome. PLoS ONE 9:e109794
Abstract	Bacteriophytochromes (BphPs) are light-sensing regulatory proteins encoded in photosynthetic and non-photosynthetic bacteria. This protein class incorporate bilin as their chromophore, with majority of them bearing a light- regulated His kinase or His kinase related module in the C-terminal. We studied the His kinase actives in the temperature range of 5°C to 40°C on two BphPs, Agp1 from Agrobacterium tumefaciens and Cph1 from cyanobacterium Synechocystis PCC 6803. As reported, the phosphorylation activities of the far red (FR) irradiated form of the holoprotein is stronger than that of the red (R) irradiated form in both phytochromes. We observed for the apoprotein and FR irradiated holoprotein of Agp1 an increase in the phosphorylation activities from 5°C to 25°C and a decrease from 25°C to 40°C. At 5°C the activities of the apoprotein were significantly lower than those of the FR irradiated holoprotein, which was opposite at 40°C. A similar temperature pattern was observed for Cph1, but the maximum of the apoprotein was at 20°C while the maximum of the FR irradiated holoprotein was at 10°C. At 40°C, prolonged R irradiation leads to an irreversible bleaching of Cph1, an effect which depends on the C-terminal His kinase module. A more prominent and reversible temperature effect on spectral properties of Agp1, mediated by the His kinase, has been reported before. His kinases in phytochromes could therefore share similar temperature characteristics. We also found that phytochrome B mutants of Arabidopsis have reduced hypocotyl growth at 37°C in darkness, suggesting that this phytochrome senses the temperature or mediates signal transduction of temperature effects.
Links	PubMed PMC4188573 Online version:10.1371/journal.pone.0109794
Keywords	Agrobacterium tumefaciens/genetics; Agrobacterium tumefaciens/metabolism; Agrobacterium tumefaciens/radiation effects; Apoproteins/genetics; Apoproteins/metabolism; Arabidopsis/genetics; Arabidopsis/metabolism; Arabidopsis/radiation effects; Arabidopsis Proteins/genetics; Arabidopsis Proteins/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Gene Expression; Light; Mutation; Phosphorylation; Phytochrome/genetics; Phytochrome/metabolism; Protein Kinases/genetics; Protein Kinases/metabolism; Protein Structure, Tertiary; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Signal Transduction; Synechocystis/genetics; Synechocystis/metabolism; Synechocystis/radiation effects; Temperature
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGRFC:Q7CY45		GO:0000155: phosphorelay sensor kinase activity	ECO:0000314:		F		Figure 1 displays that Agp1's phosphorylation activity is dependent on temperature. Figure 2 compares to another phytochrome Cph1 which has a different optimal temperature.	complete
AGRFC:Q7CY45		GO:0046777: protein autophosphorylation	ECO:0000314:		P		Figure 1 shows that the autophosphorylation of Agp1 is dependent on temperature.	complete
AGRFC:Q7CY45		GO:0000155: phosphorelay sensor kinase activity	ECO:0000304:		F		In the discussion section it is stated that histidine kinases act as temperature sensors, either as their sole function, or combined with sensing chemical factors as in VirA of Agrobacterium tumefaciens.	complete
AGRFC:Q7CY45		GO:0004673: protein histidine kinase activity	ECO:0000314:		F		Figure 1 shows that histidine kinase activity is dependent on temperature.	complete
AGRFC:Q7CY45		GO:0009883: red or far-red light photoreceptor activity	ECO:0000314:		F		Figure 1 shows that Agp1 that has been irradiated with FR light still has temperature dependency and only slightly lessened HK activity.	complete
AGRFC:Q7CY45		GO:0009585: red, far-red light phototransduction	ECO:0000314:		P		In Figure 1, the FR irradiated holoprotein version of Agp1 still confers HK activity albeit lessened than the "normal" version. Meaning the protein can utilize FR light.	complete

References

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