title: Heat shock transcriptional responses in an MC-Producing Cyanobacterium (Planktothrix agardhii) and its MC-deficient mutant under high light conditions.
abstract: Microcystins (MCs) are the most commonly-reported hepatotoxins produced by various cyanobacterial taxa in fresh waters to constitute a potential threat to human and animal health. The biological role of MCs in the producer organisms is not known, and it would be very useful to understand the driving force behind the toxin production. Recent studies have suggested that MCs may have a protective function in cells facing environmental stress. Following this starting premise, we speculate that under adverse conditions the expression of stress-related genes coding for Heat Shock Proteins (Hsp) might be different in an MC-producing strain and its MC-deficient mutant. We therefore used RT-qPCR to compare the expression of 13 hsp genes of an MC-producing strain of Planktothrix agardhii (CYA126/8) and its MC-deficient ΔmcyD mutant over different periods of exposure to high light stress (HL). Three reference genes (RGs) were selected from six candidates to normalize the RT-qPCR data. Of these three RGs (rsh, rpoD, and gltA), gltA is used here for the first time as an RG in prokaryotes. Under HL stress, five genes were found to be strongly up-regulated in both strains (htpG, dnaK, hspA, groES, and groEL). Unexpectedly, we found that the MC-producing wild type strain accumulated higher levels of htpG and dnaK transcripts in response to HL stress than the MC-deficient mutant. In addition, a significant increase in the mcyE transcript was detected in the mutant, suggesting that MCs are required under HL conditions. We discuss several possible roles of MCs in the response to HL stress through their possible involvement in the protective mechanisms of the cells.
authors.affiliation: UMR Molécules de Communication et Adaptation des Microorganismes, Muséum national d'Histoire naturelle, Paris, France.
authors.forename: Thi Du Chi
authors.initials: Tdu C
authors.lastname: Tran
authors.forename: Cecile
authors.initials: C
authors.lastname: Bernard
authors.forename: Myriam
authors.initials: M
authors.lastname: Ammar
authors.forename: Soraya
authors.initials: S
authors.lastname: Chaouch
authors.forename: Katia
authors.initials: K
authors.lastname: Comte
mesh_terms: D004307:Dose-Response Relationship, Radiation; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D005798:Genes, Bacterial / Q000235:genetics; D018869:Heat-Shock Response / Q000528:radiation effects*; D008027:Light; D052998:Microcystins / Q000096:biosynthesis*; D009154:Mutation; D015203:Reproducibility of Results; D013997:Time Factors; D014158:Transcription, Genetic / Q000528:radiation effects*; D014805:Vitamin B 12 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects
chemical_list: D052998:Microcystins; C078588:microcystin; D014805:Vitamin B 12
references.citation: Biochem Biophys Res Commun. 2007 Jan 5;352(1):36-41
references.pmid: 17107658
references.citation: PLoS One. 2011 Mar 18;6(3):e17615
references.pmid: 21445264
references.citation: Mar Genomics. 2009 Mar;2(1):11-8
references.pmid: 21798167
references.citation: Appl Environ Microbiol. 2006 Sep;72(9):6101-10
references.pmid: 16957235
references.citation: J Bacteriol. 2006 Apr;188(8):3088-98
references.pmid: 16585768
references.citation: BMC Vet Res. 2007 May 07;3:7
references.pmid: 17484782
references.citation: Microbiology (Reading). 2001 Nov;147(Pt 11):3113-9
references.pmid: 11700361
references.citation: Plant Cell. 2001 Apr;13(4):793-806
references.pmid: 11283337
references.citation: Mol Cell Proteomics. 2011 Sep;10(9):M110.003749
references.pmid: 21610102
references.citation: J Microbiol Methods. 2006 Jul;66(1):125-35
references.pmid: 16378650
references.citation: Biochem Biophys Res Commun. 2002 Jan 11;290(1):339-48
references.pmid: 11779175
references.citation: Nat Rev Genet. 2008 Aug;9(8):583-93
references.pmid: 18591982
references.citation: Environ Microbiol. 2008 Oct;10(10):2476-83
references.pmid: 18647335
references.citation: Microbiology (Reading). 2004 May;150(Pt 5):1271-1281
references.pmid: 15133090
references.citation: Appl Environ Microbiol. 1997 Jun;63(6):2206-12
references.pmid: 9172340
references.citation: Environ Microbiol Rep. 2009 Feb;1(1):27-37
references.pmid: 23765717
references.citation: Cancer Res. 2004 Aug 1;64(15):5245-50
references.pmid: 15289330
references.citation: Environ Microbiol. 2008 Dec;10(12):3337-48
references.pmid: 18759740
references.citation: Genome Biol. 2002 Jun 18;3(7):RESEARCH0034
references.pmid: 12184808
references.citation: Clin Chem. 2009 Apr;55(4):611-22
references.pmid: 19246619
references.citation: Nucleic Acids Res. 2002 May 1;30(9):e36
references.pmid: 11972351
references.citation: PLoS One. 2011;6(9):e25569
references.pmid: 21980492
references.citation: Curr Microbiol. 2002 Apr;44(4):291-6
references.pmid: 11910501
references.citation: Appl Environ Microbiol. 1995 Feb;61(2):797-800
references.pmid: 7574617
references.citation: Trends Plant Sci. 2004 May;9(5):244-52
references.pmid: 15130550
references.citation: Plant Mol Biol. 1997 Dec;35(6):763-75
references.pmid: 9426597
references.citation: Environ Microbiol. 2007 Apr;9(4):965-70
references.pmid: 17359268
references.citation: Appl Environ Microbiol. 2009 Sep;75(18):6008-12
references.pmid: 19633117
references.citation: Mol Cell. 2010 Aug 13;39(3):321-31
references.pmid: 20705236
references.citation: Appl Environ Microbiol. 2004 Nov;70(11):6370-8
references.pmid: 15528494
references.citation: Microb Ecol. 2002 Jan;43(1):107-18
references.pmid: 11984633
references.citation: Methods Enzymol. 1988;167:3-27
references.pmid: 3148836
references.citation: J Biol Chem. 1991 Jan 5;266(1):58-65
references.pmid: 1670771
references.citation: J Bacteriol. 2002 Dec;184(24):6845-58
references.pmid: 12446635
references.citation: BMC Bioinformatics. 2012 Jun 18;13:134
references.pmid: 22708584
references.citation: Toxicol Appl Pharmacol. 2005 Mar 15;203(3):192-200
references.pmid: 15737674
references.citation: Biotechnol Lett. 2004 Mar;26(6):509-15
references.pmid: 15127793
references.citation: Genes Immun. 2005 Jun;6(4):279-84
references.pmid: 15815687
references.citation: Biosci Biotechnol Biochem. 2006 Jul;70(7):1592-8
references.pmid: 16861792
references.citation: Proteomics. 2006 May;6(9):2733-45
references.pmid: 16572470
references.citation: Mol Microbiol. 2010 May;76(3):576-89
references.pmid: 20345653
references.citation: J Microbiol Methods. 2009 Feb;76(2):196-200
references.pmid: 19041906
references.citation: J Exp Biol. 2004 Jan;207(Pt 1):15-9
references.pmid: 14638828
references.citation: Appl Environ Microbiol. 2003 Dec;69(12):7289-97
references.pmid: 14660378
references.citation: Curr Microbiol. 2003 Oct;47(4):341-6
references.pmid: 14629017
references.citation: Chem Biol. 2000 Oct;7(10):753-64
references.pmid: 11033079
references.citation: BMC Mol Biol. 2010 Jan 20;11:8
references.pmid: 20089196
references.citation: Appl Environ Microbiol. 2000 Aug;66(8):3387-92
references.pmid: 10919796
references.citation: Toxicon. 2009 Sep 1;54(3):302-12
references.pmid: 19397919
references.citation: Annu Rev Biochem. 1986;55:1151-91
references.pmid: 2427013
references.citation: Annu Rev Physiol. 1999;61:243-82
references.pmid: 10099689
references.citation: J Ind Microbiol Biotechnol. 2011 Sep;38(9):1279-86
references.pmid: 21104423