Content and biosynthesis of polyamines in salt and osmotically stressed cells ofSynechocystissp. PCC 6803

Abstract

The effects of various NaCl and sorbitol concentrations in the growth medium on polyamine content and on two enzymes of the polyamine biosynthesis pathway, arginine decarboxylase (ADC) and S-adenosyl methionine decarboxylase (SAMDC), were investigated in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Synechocystis cells showed no difference in growth rate when the concentration of NaCl was raised up to 550 mM. The growth rate decreased at 300 mM sorbitol, and complete inhibition of growth occurred at concentrations of v 700 mM sorbitol. Salt stress induced a moderate increase in the total cellular polyamine content, spermine in particular. Osmotic stress caused an apparent increase in the total cellular polyamine content with a marked increase of spermidine induced by 700 mM sorbitol. Importantly, a low level of spermine, which so far has never been detected in cyanobacteria, could be found in Synechocystis sp. PCC 6803. ADC, a key enzyme for putrescine synthesis, was unaffected by salt stress but showed a six-fold increase in enzyme activity upon osmotic stress imposed by 700 mM sorbitol. SAMDC, another important enzyme for spermidine and spermine synthesis, responded to salt and osmotic stresses similarly to the pattern observed for ADC. An analysis by reverse transcription-polymerase chain reaction revealed an increase of ADC mRNA level in cells under salt and osmotic stresses. Most importantly, the increase of ADC mRNA was attributed to its slower turnover rate under both stress conditions. Interestingly, the samdc gene(s) of Synechocystis appear to be unique since comparisons with known gene sequences from other organisms resulted in no homologous sequences identified in the Synechocystis genome. ß

Exogenous proline and proline-enriched Lolium perenne leaf extract protects against phytotoxic effects of nickel and salinity in Pisum sativum by altering polyamine metabolism in leaves

“…Generally, plant genotypes with high stresstolerance capacity have the maximum potential to elevate polyamine biosynthesis in response to various abiotic stresses, including salinity and nickel stress. Under stressed conditions, polyamines play a major role in maintaining a balance between ratios of cations and anions (Jantaro et al, 2003;Tonon et al, 2004). The plants submitted to NaCl and/or NiCl 2 stress exhibited a marked increase in leaf polyamine content.…”

A Comprehensively Curated Genome-Scale Two-Cell Model for the Heterocystous Cyanobacterium Anabaena sp. PCC 7120

“…Source of Data and Reference Pigments Analysis of carotenoid composition (Takaichi et al, 2005;Takaichi and Mochimaru, 2007;Mochimaru et al, 2008;Graham and Bryant, 2009 No genes could be identified for the biosynthesis of spermidine (Jantaro et al, 2003;Incharoensakdi et al, 2010).…”

Role of Spermidine in Overwintering of Cyanobacteria

“…Jantaro et al (21) reported that Synechocystis 6803 possesses spermidine, spermine, and putrescine, with spermidine as the most abundant polyamine (21). However, spermidine was the only detectable polyamine in Synechocystis 6803 maintained in our laboratory (see Fig.…”

“…Polyamines were extracted from Synechocystis 6803 with 5% cold HClO 4 and derivatized with benzoyl chloride as reported earlier (21). The derivatization of polyamine standards (Sigma Chemicals) was performed similarly.…”

“…For these characteristics, polyamines are involved in variable cellular activities of prokaryotes, such as biofilm formation (15,16), modification of outer membrane permeability (17,18), and enhancement of acid resistance (19,20). In cyanobacteria, there are certain clues that may relate polyamines to osmotic tolerance (21), but little is known about the role of polyamines in adaptation to freshwater environments. Because polyamines in plants are involved in cold responses and can enhance tolerance to cold and freezing temperatures (22), those in cyanobacteria may relate to overwintering.…”