scholarly journals The hetC Gene Is a Direct Target of the NtcA Transcriptional Regulator in Cyanobacterial Heterocyst Development

1999 ◽  
Vol 181 (21) ◽  
pp. 6664-6669 ◽  
Author(s):  
Alicia M. Muro-Pastor ◽  
Ana Valladares ◽  
Enrique Flores ◽  
Antonia Herrero
Keyword(s):  
Dna Hybridization ◽  
Transcription Start Point ◽  
Promoter Activation ◽  
Transcription Start ◽  
Genes Expression ◽  
Dna Fragment ◽  
Direct Target ◽  
Translational Start ◽  
Pcc 7120 ◽  
Heterocyst Development

ABSTRACT The heterocyst is the site of nitrogen fixation in aerobically grown cultures of some filamentous cyanobacteria. Heterocyst development in Anabaena sp. strain PCC 7120 is dependent on the global nitrogen regulator NtcA and requires, among others, the products of the hetR and hetC genes. Expression of hetC, tested by RNA- DNA hybridization, was impaired in an ntcA mutant. A nitrogen-regulated, NtcA-dependent putative transcription start point was localized at nucleotide −571 with respect to the hetC translational start. Sequences upstream from this transcription start point exhibit the structure of the canonical cyanobacterial promoter activated by NtcA, and purified NtcA protein specifically bound to a DNA fragment containing this promoter. Activation of expression of hetC during heterocyst development appears thus to be directly operated by NtcA. NtcA-mediated activation of hetR expression was not impaired in a hetC mutant, indicating that HetC is not an NtcA-dependent element required for hetR induction.

scholarly journals NtcA-Regulated Heterocyst Differentiation Genes hetC and devB from Anabaena sp. Strain PCC 7120 Exhibit a Similar Tandem Promoter Arrangement

2009 ◽  
Vol 191 (18) ◽  
pp. 5765-5774 ◽  
Author(s):  
Alicia M. Muro-Pastor ◽  
Enrique Flores ◽  
Antonia Herrero
Keyword(s):  
Promoter Region ◽  
Transcriptional Start Site ◽  
Short Version ◽  
Start Site ◽  
Transcription Start ◽  
Promoter Regions ◽  
Heterocyst Differentiation ◽  
Translational Start ◽  
Pcc 7120 ◽  
Diazotrophic Growth

ABSTRACT Transcription of the hetC gene, whose product is required for heterocyst differentiation, takes place from a long promoter region that includes the previously described HetR-independent, NtcA-activated promoter producing transcripts with a 5′ end corresponding to position −571 with respect to the translational start site of hetC. Northern blot analysis indicated that the accumulation of hetC transcripts depends on HetR, and a second transcriptional start site located at position −293 that leads to NtcA-dependent, HetR-dependent inducible transcription of hetC was identified. Upon nitrogen stepdown, expression of a P hetC ::gfp fusion was transiently induced in specific cells that were differentiating into heterocysts, both when the whole promoter region (containing transcription start points −571 and −293) or a short version (containing only the transcription start point −293) was used. Expression of hetC from the −293 position was delayed in a strain bearing a deleted promoter region lacking sequences upstream from position −570. Such a strain was still able to differentiate functional heterocysts and to grow diazotrophically, although diazotrophic growth was impaired under certain conditions. Similarly, a second, NtcA-dependent, HetR-dependent transcriptional start site was identified at position −454 in the promoter region upstream from the devBCA operon encoding an ABC transport system involved in heterocyst maturation, in which an NtcA-dependent promoter producing transcripts starting at position −704 had been previously noted. Thus, the hetC and devBCA promoter regions exhibit similar tandem promoter arrangements.

sae is essential for expression of the staphylococcal adhesins Eap and Emp

Microbiology ◽  
2005 ◽  
Vol 151 (6) ◽  
pp. 1789-1800 ◽  
Author(s):  
Niamh Harraghy ◽  
Jan Kormanec ◽  
Christiane Wolz ◽  
Dagmar Homerova ◽  
Christiane Goerke ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Extracellular Matrix ◽  
Virulence Factor ◽  
Eukaryotic Cells ◽  
Transcription Start Point ◽  
Chronic Infections ◽  
Transcription Start ◽  
Regulatory Mutants ◽  
Global Regulators ◽  
Glucose Analysis

Eap and Emp are two Staphylococcus aureus adhesins initially described as extracellular matrix binding proteins. Eap has since emerged as being important in adherence to and invasion of eukaryotic cells, as well as being described as an immunomodulator and virulence factor in chronic infections. This paper describes the mapping of the transcription start point of the eap and emp promoters. Moreover, using reporter-gene assays and real-time PCR in defined regulatory mutants, environmental conditions and global regulators affecting expression of eap and emp were investigated. Marked differences were found in expression of eap and emp between strain Newman and the 8325 derivatives SH1000 and 8325-4. Moreover, both genes were repressed in the presence of glucose. Analysis of expression of both genes in various regulatory mutants revealed that sarA and agr were involved in their regulation, but the data suggested that there were additional regulators of both genes. In a sae mutant, expression of both genes was severely repressed. sae expression was also reduced in the presence of glucose, suggesting that repression of eap and emp in glucose-containing medium may, in part, be a consequence of a decrease in expression of sae.

Constitutive expression of cat-86 associated with a change in the transcription start point

Gene ◽  
1991 ◽  
Vol 105 (1) ◽  
pp. 113-117 ◽  
Author(s):  
Nicholas P. Ambulos ◽  
Un Jin Kim ◽  
Elizabeth J. Rogers ◽  
Paul S. Lovett
Keyword(s):  
Constitutive Expression ◽  
Transcription Start Point ◽  
Transcription Start

scholarly journals Functional and Transcriptional Analyses of a Fengycin Synthetase Gene, fenC, from Bacillus subtilis

1999 ◽  
Vol 181 (16) ◽  
pp. 5060-5067 ◽  
Author(s):  
Tsuey-Pin Lin ◽  
Chyi-Liang Chen ◽  
Li-Kwan Chang ◽  
Johannes Scheng-Ming Tschen ◽  
Shih-Tung Liu
Keyword(s):  
Stationary Phase ◽  
Transcription Start Site ◽  
Primer Extension ◽  
Initiation Codon ◽  
Acid Activation ◽  
Start Site ◽  
Transcription Start ◽  
Amino Acid Activation ◽  
Dna Fragment ◽  
Insight Into

ABSTRACT A 37-kb DNA fragment containing five fengycin synthetase genes, including fenC, fenD, fenE,fenA, and fenB, was cloned and sequenced. Among these genes, fenC encodes a fengycin synthetase 2,560 amino acids long with an estimated molecular mass of 287 kDa. This protein contains two amino acid activation modules, FenC1 and FenC2, which activate l-glutamic acid and l-ornithine, respectively. Primer extension, using mRNA isolated from the log-phase cells, identified a transcription start site located 86 nucleotides upstream from the initiation codon of fenC, implying that a promoter is located upstream from the start site. Primer extension using total RNA isolated from stationary-phase cells also identified a transcription start site located 61 nucleotides upstream from the initiation codon of fenC. Gene fusion studies demonstrated that in nHA medium, the cells transcribe the fengycin synthetase genes at two different stages of cell growth. The promoter is active during the log phase, and the activity reaches the highest level during the late log phase. The activity decreases sharply but is maintained at a low level for approximately 24 h after cells enter the early stationary phase. The results of this investigation also suggest that the transcription of fenC is positively regulated during the late log phase. Results presented herein provide further insight into fengycin synthesis by B. subtilis F29-3.

scholarly journals Anabaena sp. Strain PCC 7120 hetY Gene Influences Heterocyst Development

2003 ◽  
Vol 185 (23) ◽  
pp. 6995-7000 ◽  
Author(s):  
Ho-Sung Yoon ◽  
Martin H. Lee ◽  
Jin Xiong ◽  
James W. Golden
Keyword(s):  
Atp Binding ◽  
Binding Motif ◽  
Filamentous Cyanobacterium ◽  
Hypothetical Proteins ◽  
Nitrogen Fixing ◽  
Fixed Nitrogen ◽  
Anabaena Sp ◽  
Time Required ◽  
Pcc 7120 ◽  
Heterocyst Development

ABSTRACT The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 responds to starvation for fixed nitrogen by producing a semiregular pattern of nitrogen-fixing cells called heterocysts. Overexpression of the hetY gene partially suppressed heterocyst formation, resulting in an abnormal heterocyst pattern. Inactivation of hetY increased the time required for heterocyst maturation and caused defects in heterocyst morphology. The 489-bp hetY gene (alr2300), which is adjacent to patS (asl2301), encodes a protein that belongs to a conserved family of bacterial hypothetical proteins that contain an ATP-binding motif.

alr0117, a two-component histidine kinase gene, is involved in heterocyst development in Anabaena sp. PCC 7120

Microbiology ◽  
2004 ◽  
Vol 150 (2) ◽  
pp. 447-453 ◽  
Author(s):  
Degang Ning ◽  
Xudong Xu
Keyword(s):  
Histidine Kinase ◽  
Regulatory System ◽  
Gene Encoding ◽  
Kinase Gene ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Polysaccharide Layer ◽  
Heterocyst Development

Anabaena sp. PCC 7120 was mutagenized by transposon Tn5-1087b, generating a mutant whose heterocysts lack the envelope polysaccharide layer. The transposon was located between nucleotides 342 and 343 of alr0117, a 918 bp gene encoding a histidine kinase for a two-component regulatory system. Complementation of the mutant with a DNA fragment containing alr0117 and targeted inactivation of the gene confirmed that alr0117 is involved in heterocyst development. RT-PCR showed that alr0117 was constitutively expressed in the presence or absence of a combined-nitrogen source. hepA and patB, the two genes turned on during wild-type heterocyst development, were no longer activated in an alr0117-null mutant. The two-component signal transduction system involving alr0117 may control the formation of the envelope polysaccharide layer and certain late events essential to the function of heterocysts.

The genetic and physical basis of variability in Escherichia coli strains carrying a reference Inc N group plasmid

1981 ◽  
Vol 27 (6) ◽  
pp. 616-626 ◽  
Author(s):  
M. Konarska-Kozlowska ◽  
V. N. Iyer
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Sequence Homology ◽  
Dna Hybridization ◽  
Tetracycline Resistance ◽  
Resistance Marker ◽  
E Coli ◽  
Reference Plasmid ◽  
Dna Fragment ◽  
K 12

The nature and basis of variability in the conjugational behaviour of RM98+ (RM98-carrying) strains of Escherichia coli K-12 that are otherwise similar in phenotype was studied. An explanation for such variability is provided.Some RM98+ strains of E. coli have a plasmid aggregate, which upon conjugation yields two different conjugative plasmids. The first (pCU1) is an N conjugative group plasmid by all available criteria. The second (pCU2) could not be placed in any conjugative group known among the Enterobacteriaceae. Reciprocal DNA hybridization experiments and the gel patterns displayed by the two plasmid DNAs upon digestion with different restriction endonucleases indicate no extensive sequence homology between pCU1 and pCU2. pCU2 DNA is much longer than pCU1 DNA.Despite the absence of extensive homology, the DNA of pCU1 and pCU2 can interact. Derivatives can be selected that have all the antibiotic markers of the aggregate plasmid but that neither contain nor segregate pCU2. It is shown that in such strains a DNA fragment of molecular weight 7.9 × 106 has been added to pCU1 concurrently with a tetracycline resistance marker originally present in pCU2 and absent in pCU1. These observations suggest that tetracycline resistance in pCU2 may be part of a large translocatable element.RM98 has been used to designate a reference Inc N group plasmid. The results presented indicate that this can lead to ambiguity. pCU1 would now be the appropriate reference plasmid.

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