LexA regulates the bidirectional hydrogenase in the cyanobacterium <i>Synechocystis</i> sp. PCC 6803 as a transcription activator

Gutekunst, Kirstin; Phunpruch, Saranya; Schwarz, Christoph; Schuchardt, Sven; Schulz-Friedrich, Rüdiger; Appel, Jens

doi:10.1111/j.1365-2958.2005.04867.x

Cited by 100 publications

(115 citation statements)

References 69 publications

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“…The LexA-like protein binds two sites in the hydrogenase (hox) operon and may function as a transcription activator (Gutekunst et al, 2005;Oliveira & Lindblad, 2005). Consistent with this, we observed that transcript levels of the hox operon (sll1220-sll1226) increased in both strains under low oxygen (Table 2).…”

Section: The Absence Of Hik31 Alters Transcriptional Response To Low supporting

confidence: 75%

Gene expression under low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803 demonstrates Hik31-dependent and -independent responses

2011

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We have investigated the response of the cyanobacterium Synechocystis sp. PCC 6803 during growth at very low O 2 concentration (bubbled with 99.9 % N 2 /0.1 % CO 2 ). Significant transcriptional changes upon low-O 2 incubation included upregulation of a cluster of genes that contained psbA1 and an operon that includes a gene encoding the two-component regulatory histidine kinase, Hik31. This regulatory cluster is of particular interest, since there are virtually identical copies on both the chromosome and plasmid pSYSX. We used a knockout mutant lacking the chromosomal copy of hik31 and studied differential transcription during the aerobiclow-O 2 transition in this DHik31 strain and the wild-type. We observed two distinct responses to this transition, one Hik31 dependent, the other Hik31 independent. The Hik31-independent responses included the psbA1 induction and genes involved in chlorophyll biosynthesis. In addition, there were changes in a number of genes that may be involved in assembling or stabilizing photosystem (PS)II, and the hox operon and the LexA-like protein (Sll1626) were upregulated during low-O 2 growth. This family of responses mostly focused on PSII and overall redox control. There was also a large set of genes that responded differently in the absence of the chromosomal Hik31. In the vast majority of these cases, Hik31 functioned as a repressor and transcription was enhanced when Hik31 was deleted. Genes in this category encoded both core and peripheral proteins for PSI and PSII, the main phycobilisome proteins, chaperones, the ATP synthase cluster and virtually all of the ribosomal proteins. These findings, coupled with the fact that DHik31 grew better than the wild-type under low-O 2 conditions, suggested that Hik31 helps to regulate growth and overall cellular homeostasis. We detected changes in the transcription of other regulatory genes that may compensate for the loss of Hik31. We conclude that Hik31 regulates an important series of genes that relate to energy production and growth and that help to determine how Synechocystis responds to changes in O 2 conditions.

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Section: The Absence Of Hik31 Alters Transcriptional Response To Low supporting

confidence: 75%

Gene expression under low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803 demonstrates Hik31-dependent and -independent responses

2011

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“…4 shows the hydrogenase operon which encodes all proteins required for pentameric bidirectional Ni-Fe hydrogenase (HoxEFUYH). This operon uses a single TSS located 168 nt upstream of hoxE (19), and its regulation is well studied (19)(20)(21). Intriguingly, we found that the operon is framed by two highly expressed ncRNAs, one of which [SyR1 (14)], was strongly upregulated under high light, whereas the other (ncr0700) was maximally expressed in the dark (Fig.…”

Section: Resultsmentioning

confidence: 62%

An experimentally anchored map of transcriptional start sites in the model cyanobacterium Synechocystis sp. PCC6803

Mitschke

Georg

Scholz

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

349

459

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There has been an increasing interest in cyanobacteria because these photosynthetic organisms convert solar energy into biomass and because of their potential for the production of biofuels. However, the exploitation of cyanobacteria for bioengineering requires knowledge of their transcriptional organization. Using differential RNA sequencing, we have established a genome-wide map of 3,527 transcriptional start sites (TSS) of the model organism Synechocystis sp. PCC6803. One-third of all TSS were located upstream of an annotated gene; another third were on the reverse complementary strand of 866 genes, suggesting massive antisense transcription. Orphan TSS located in intergenic regions led us to predict 314 noncoding RNAs (ncRNAs). Complementary microarray-based RNA profiling verified a high number of noncoding transcripts and identified strong ncRNA regulations. Thus, ∼64% of all TSS give rise to antisense or ncRNAs in a genome that is to 87% protein coding. Our data enhance the information on promoters by a factor of 40, suggest the existence of additional small peptide-encoding mRNAs, and provide corrected 5′ annotations for many genes of this cyanobacterium. The global TSS map will facilitate the use of Synechocystis sp. PCC6803 as a model organism for further research on photosynthesis and energy research.gene expression regulation | promoter prediction | RNA polymerase

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“…Second, in the cyanobacterium Synechocystis sp. PCC 6803, LexA has been found to activate expression of the hox operon, which encodes the bidirectional NiFe-hydrogenase of this organism (Gutekunst et al, 2005). In addition, the dnaB gene and the predicted coding region CC_2433 from Caulobacter crescentus are downregulated in a lexA mutant, and both genes contain SOS boxes with significant scores.…”

Section: Is Lexa Involved In Transcriptional Activation Of Sos Gene Ementioning

confidence: 99%

Genetic makeup of the Corynebacterium glutamicum LexA regulon deduced from comparative transcriptomics and in vitro DNA band shift assays

et al. 2009

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The lexA gene of Corynebacterium glutamicum ATCC 13032 was deleted to create the mutant strain C. glutamicum NJ2114, which has an elongated cell morphology and an increased doubling time. To characterize the SOS regulon in C. glutamicum, the transcriptomes of NJ2114 and a DNA-damage-induced wild-type strain were compared with that of a wild-type control using DNA microarray hybridization. The expression data were combined with bioinformatic pattern searches for LexA binding sites, leading to the detection of 46 potential SOS boxes located upstream of differentially expressed transcription units. Binding of a hexahistidyl-tagged LexA protein to 40 double-stranded oligonucleotides containing the potential SOS boxes was demonstrated in vitro by DNA band shift assays. It turned out that LexA binds not only to SOS boxes in the promoteroperator region of upregulated genes, but also to SOS boxes detected upstream of downregulated genes. These results demonstrated that LexA controls directly the expression of at least 48 SOS genes organized in 36 transcription units. The deduced genes encode a variety of physiological functions, many of them involved in DNA repair and survival after DNA damage, but nearly half of them have hitherto unknown functions. Alignment of the LexA binding sites allowed the corynebacterial SOS box consensus sequence TcGAA(a/c)AnnTGTtCGA to be deduced. Furthermore, the common intergenic region of lexA and the differentially expressed divS-nrdR operon, encoding a cell division suppressor and a regulator of deoxyribonucleotide biosynthesis, was characterized in detail. Promoter mapping revealed differences in divS-nrdR expression during SOS response and normal growth conditions. One of the four LexA binding sites detected in the intergenic region is involved in regulating divS-nrdR transcription, whereas the other sites are apparently used for negative autoregulation of lexA expression.

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LexA regulates the bidirectional hydrogenase in the cyanobacterium Synechocystis sp. PCC 6803 as a transcription activator

Cited by 100 publications

References 69 publications

Gene expression under low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803 demonstrates Hik31-dependent and -independent responses

Gene expression under low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803 demonstrates Hik31-dependent and -independent responses

An experimentally anchored map of transcriptional start sites in the model cyanobacterium Synechocystis sp. PCC6803

Genetic makeup of the Corynebacterium glutamicum LexA regulon deduced from comparative transcriptomics and in vitro DNA band shift assays

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