Expression and possible role of stress-responsive proteins inAnabaena

Apte, Shree Kumar; Fernandes, Tonina; Badran, Hala Mahfouz; Ballal, Anand

doi:10.1007/bf02936133

Cited by 29 publications

(20 citation statements)

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“…Earlier work from our laboratory demonstrated that the Hsp60 family chaperonins are commonly induced generalstress proteins in response to heat, salinity, and osmotic stresses in Anabaena strains (2,4). Our recent work elucidated a major role of the cpn60 gene in the protection from photosynthesis and the nitrate reductase activity of N-supplemented Anabaena cultures (21).…”

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confidence: 75%

“…Molecular chaperones play a major role in the conformational homeostasis of cellular proteins (13,16,24,26) by (i) proper folding of nascent polypeptide chains; (ii) facilitating protein translocation and maturation to functional conformation, including multiprotein complex assembly; (iii) refolding of misfolded proteins; (iv) sequestering damaged proteins to aggregates; and (v) solubilizing protein aggregates for refolding or degradation. Present at basal levels under optimum growth conditions in bacteria, the expression of chaperonins is significantly enhanced during heat shock and other stresses (2,25,32).…”

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confidence: 99%

“…One occurs as a solitary gene, cpn60 (17,21), while the other is juxtaposed to its cochaperonin encoding genes groES and constitutes a bicistronic operon groESL (7,19,31). The two hsp60 genes encode a 59-kDa GroEL and a 61-kDa Cpn60 protein in Anabaena (2,20). Both the Hsp60 chaperonins are strongly expressed during heat stress, resulting in the superior thermotolerance of Anabaena, compared to the transient expression of the Hsp60 chaperonins in Escherichia coli (20).…”

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confidence: 99%

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Overexpression of the groESL Operon Enhances the Heat and Salinity Stress Tolerance of the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC7120

Chaurasia

Apte

2009

Appl Environ Microbiol

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The bicistronic groESL operon, encoding the Hsp60 and Hsp10 chaperonins, was cloned into an integrative expression vector, pFPN, and incorporated at an innocuous site in the Anabaena sp. strain PCC7120 genome. In the recombinant Anabaena strain, the additional groESL operon was expressed from a strong cyanobacterial P psbA1 promoter without hampering the stress-responsive expression of the native groESL operon. The net expression of the two groESL operons promoted better growth, supported the vital activities of nitrogen fixation and photosynthesis at ambient conditions, and enhanced the tolerance of the recombinant Anabaena strain to heat and salinity stresses.

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confidence: 75%

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confidence: 99%

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confidence: 99%

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Overexpression of the groESL Operon Enhances the Heat and Salinity Stress Tolerance of the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC7120

Chaurasia

Apte

2009

Appl Environ Microbiol

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“…In contrast, the GroEL2 polypeptide is much less conserved. The GroEL/GroES system is a major chaperone system in all bacteria and the ways in which this system responds to stress conditions have been extensively studied in cyanobacteria (Hihara et al, 2001;Apte et al, 1998). For example, the transcripts groEL1 and groEL2 have been shown to accumulate in response to elevated temperatures (Kovacs et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Effects of high light on transcripts of stress-associated genes for the cyanobacteria Synechocystis sp. PCC 6803 and Prochlorococcus MED4 and MIT9313

Mary

Grossman

et al. 2004

Microbiology

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Cyanobacteria constitute an ancient, diverse and ecologically important bacterial group. The responses of these organisms to light and nutrient conditions are finely controlled, enabling the cells to survive a range of environmental conditions. In particular, it is important to understand how cyanobacteria acclimate to the absorption of excess excitation energy and how stress-associated transcripts accumulate following transfer of cells from low-to high-intensity light. In this study, quantitative RT-PCR was used to monitor changes in levels of transcripts encoding chaperones and stress-associated proteases in three cyanobacterial strains that inhabit different ecological niches: the freshwater strain Synechocystis sp. PCC 6803, the marine high-light-adapted strain Prochlorococcus MED4 and the marine low-light-adapted strain Prochlorococcus MIT9313. Levels of transcripts encoding stress-associated proteins were very sensitive to changes in light intensity in all of these organisms, although there were significant differences in the degree and kinetics of transcript accumulation. A specific set of genes that seemed to be associated with high-light adaptation (groEL/groES, dnaK2, dnaJ3, clpB1 and clpP1) could be targeted for more detailed studies in the future. Furthermore, the strongest responses were observed in Prochlorococcus MED4, a strain characteristic of the open ocean surface layer, where hsp genes could play a critical role in cell survival.

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“…Accumulation of inorganic ions in the cytoplasm will give a toxic effect on cell metabolism. The mechanism to combat the salinity stress involves the prevention of Na + influx by pumping out excess Na + , resulting in salt tolerance (Apte et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Upregulation of thiamine (vitamin B1) biosynthesis gene upon stress application inAnabaenasp. andNannochloropsis oculata

2017

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Thiamine pyrophosphate (TPP), the active form of thiamine is a cofactor for enzymes involved in central metabolism pathways. However, it is also known to have a role as a stress signaling molecule in response to environmental changes. Anabaena sp. and N. oculata are microorganisms which are abundantly found in Malaysia's freshwater and marine ecosystem. However, not much studies have been done especially in regards to thiamine biosynthesis. This work aimed to amplify of gene transcripts coding for thiamine biosynthesis enzymes besides looking at the expression of thiamine biosynthesis genes upon stress application. Various stress inducers were applied to the cultures and RNA was extracted at different time points. The first two genes, ThiC and ThiG/Thi4 encoding enzymes of the pyrimidine and thiazole branch respectively in the thiamine biosynthesis pathway were identified and amplified. The expression of the genes were analysed via RT-PCR and the intensity of bands were analysed using ImageJ software. The results showed up to 4-fold increase in the expression of ThiC and ThiG gene transcript as compared to control sample in Anabaena sp. ThiC gene in N. oculata showed an expression of 6-fold higher as compared to control sample. In conclusion, stresses induced the expression of the gene coding for one of the most important enzymes in thiamine biosynthesis pathway. This is an agreement with the hypothesis that overexpression of thiamine is crucial in assisting plants to combat abiotic stresses.Keywords Thiamine, Vitamin B1, Stress, Microalgae, Cyanobacteria, Gene expression IntroductionIn recent years, oxygenic phototrophic microorganism such as cyanobacteria and microalgae have been the center of interest as they are ideal models for many applications. They bloom rapidly with minimal amount of nutrients such as light, sugar, carbon dioxide, nitrogen, potassium and phosphorus (Behera, 2015). As compared to plants, they do not require land to grow and they are fast growing with simple genetic background to manipulate. Prokaryotic cyanobacteria do not have membrane-bound cell organelles and a defined nucleus whereas eukaryotic microalgae are more complex in structure and possess nucleus (Seckbach, 2007).Thiamine and its active form, thiamine pyrophosphate (TPP) play important roles in human nutrition and central metabolism (Tunc-Ozdemir et al. 2009, Guan et al., 2014. Besides that, in recent studies thiamine and TPP have been reported as crucial stress-response molecules in plant adaptations to counteract different abiotic stress conditions (Tunc-Ozdemir et al. 2009;Rapala-Kozik et al. 2012). It is hypothesized that thiamine enhances tolerance to oxidative stress via salicylic acid (SA) signaling pathway (Ahn et al. 2007).Presently, cyanobacteria and microalgae are not fully utilised as a source for thiamine production. Knowledge of thiamine biosynthesis pathway will pave the way for manipulation of thiamine biosynthesis for various purposes. Thiamine that are available in the market today are mainly synthe...

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Expression and possible role of stress-responsive proteins inAnabaena

Cited by 29 publications

References 37 publications

Overexpression of the groESL Operon Enhances the Heat and Salinity Stress Tolerance of the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC7120

Overexpression of the groESL Operon Enhances the Heat and Salinity Stress Tolerance of the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC7120

Effects of high light on transcripts of stress-associated genes for the cyanobacteria Synechocystis sp. PCC 6803 and Prochlorococcus MED4 and MIT9313

Upregulation of thiamine (vitamin B1) biosynthesis gene upon stress application inAnabaenasp. andNannochloropsis oculata

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