Clustered genes required for synthesis and deposition of envelope glycolipids in <i>Anabaena</i> sp. strain PCC 7120

Fan, Qing; Huang, Guo N.; Lechno‐Yossef, Sigal; Wölk, C. Peter; Kaneko, Takakazu; Tabata, Satoshi

doi:10.1111/j.1365-2958.2005.04818.x

Cited by 93 publications

(142 citation statements)

References 73 publications

Supporting

Mentioning

131

Contrasting

Order By: Relevance

“…The hglE2 gene is necessary for the heterocyst glycolipid layer and is developmentally upregulated during the middle stage of heterocyst differentiation (1,15,55). In the sigE mutant strain, the hglE2 expression levels at 12 h were similar to those in the wild-type strain; however, by 36 h after nitrogen step-down, the transcript levels of hglE2 were only half of the wild-type levels.…”

Section: Discussionmentioning

confidence: 93%

“…We selected nifH, fdxH (encoding a heterocyst-specific ferredoxin), and hupL (encoding the large subunit of uptake hydrogenase) as genes that are expressed during late stages of heterocyst development (9,52). For a gene expressed during the middle stages of heterocyst development, we selected hglE2 (all1646), which encodes a type I polyketide synthase potentially involved in heterocyst glycolipid synthesis (8,15). For a baseline control mRNA, the expression of the housekeeping gene rpoA, which encodes the RNA polymerase alpha subunit, was analyzed by qRT-PCR during heterocyst development.…”

Section: Resultsmentioning

confidence: 99%

“…The expression of these genes is upregulated during the early stages of heterocyst differentiation. Synthesis of the glycolipid layer requires the expression of hglB, hglC, hglD, hglE (hglE A ), hglK, and devBCA, which are all upregulated early during heterocyst differentiation (4,15,25). A second cluster of hgl genes includes the hglE2 gene (all1646), which shows devH-dependent upregulation after heterocyst induction (45).…”

mentioning

confidence: 99%

See 2 more Smart Citations

The sigE Gene Is Required for Normal Expression of Heterocyst-Specific Genes in Anabaena sp. Strain PCC 7120

et al. 2011

View full text Add to dashboard Cite

The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 produces specialized cells for nitrogen fixation called heterocysts. Previous work showed that the group 2 sigma factor sigE (alr4249; previously called sigF) is upregulated in differentiating heterocysts 16 h after nitrogen step-down. We now show that the sigE gene is required for normal heterocyst development and normal expression levels of several heterocyst-specific genes. Mobility shift assays showed that the transcription factor NtcA binds to sites in the upstream region of sigE and that this binding is enhanced by 2-oxoglutarate (2-OG). Deletions of the region containing the NtcA binding sites in P sigE -gfp reporter plasmids showed that the sites contribute to normal developmental regulation but are not essential for upregulation in heterocysts. Northern RNA blot analysis of nifH mRNA revealed delayed and reduced transcript levels during heterocyst differentiation in a sigE mutant background. Quantitative reverse transcription-PCR (qRT-PCR) analyses of the sigE mutant showed lower levels of transcripts for nifH, fdxH, and hglE2 but normal levels for hupL. We developed a P nifHD -gfp reporter construct that showed strong heterocyst-specific expression. Time-lapse microscopy of the P nifHD -gfp reporter in a sigE mutant background showed delayed development and undetectable green fluorescent protein (GFP) fluorescence. Overexpression of sigE caused accelerated heterocyst development, an increased heterocyst frequency, and premature expression of GFP fluorescence from the P nifHD -gfp reporter.

show abstract

Section: Discussionmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

The sigE Gene Is Required for Normal Expression of Heterocyst-Specific Genes in Anabaena sp. Strain PCC 7120

et al. 2011

View full text Add to dashboard Cite

show abstract

“…We excluded the MFS 2-type transporter from subsequent studies because they are known to be involved in sugar transport (45)(46)(47)(48). A mutant of hgdC (AFS-I-hgdC), a plasma membrane ABC transporter involved in heterocyst development (all5346) (52), was used as a negative control. The strains generated were fully segregated, because no wild type gene was detectable (Fig.…”

Section: Table 3 Kinetic Parameters Determined In This Studymentioning

confidence: 99%

The TolC-like Protein HgdD of the Cyanobacterium Anabaena sp. PCC 7120 Is Involved in Secondary Metabolite Export and Antibiotic Resistance

Hahn

Stevanovic

Mirus

et al. 2012

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background:The metabolite and antibiotic export system of cyanobacteria is largely unexplored. Results: Uptake of ethidium bromid by Anabaena sp. depends on porin-type activity while its seceretion relies on HgdD. Conclusion:The antibiotic export of cyanobacteria involves a proton gradient-driven TolC activity and MFS-type proteins. Significance: TolC of Anabaena sp. is placed in the context of antibiotic uptake and export.

show abstract

“…HetR is a transcriptional regulator that interacts directly with DNA to modulate the expression of genes. The HetR regulon includes hetR itself, as well as a gene encoding an inhibitor of HetR activity, patS (12,14). It is through the interaction of HetR and PatS that the spatial patterning of differentiating cells is determined.…”

Section: T He Krebs Cycle Intermediate 2-oxoglutarate (2-og) Is An Inmentioning

confidence: 99%

ThetrpEGene Negatively Regulates Differentiation of Heterocysts at the Level of Induction in Anabaena sp. Strain PCC 7120

et al. 2014

View full text Add to dashboard Cite

Levels of 2-oxoglutarate (2-OG) reflect nitrogen status in many bacteria. In heterocystous cyanobacteria, a spike in the 2-OG level occurs shortly after the removal of combined nitrogen from cultures and is an integral part of the induction of heterocyst differentiation. In this work, deletion of one of the two annotated trpE genes in Anabaena sp. strain PCC 7120 resulted in a spike in the 2-OG level and subsequent differentiation of a wild-type pattern of heterocysts when filaments of the mutant were transferred from growth on ammonia to growth on nitrate. In contrast, 2-OG levels were unaffected in the wild type, which did not differentiate under the same conditions. An inverted-repeat sequence located upstream of trpE bound a central regulator of differentiation, HetR, in vitro and was necessary for HetR-dependent transcription of a reporter fusion and complementation of the mutant phenotype in vivo. Functional complementation of the mutant phenotype with the addition of tryptophan suggested that levels of tryptophan, rather than the demonstrated anthranilate synthase activity of TrpE, mediated the developmental response of the wild type to nitrate. A model is presented for the observed increase in 2-OG in the trpE mutant. The Krebs cycle intermediate 2-oxoglutarate (2-OG) is an intracellular indicator of nitrogen limitation in many bacteria (reviewed in reference 1). It is the carbon skeleton for assimilation of ammonia in bacteria that primarily use the GS-GOGAT system, and therefore, the concentration of 2-OG rises when ammonia is not available. Sensors of 2-OG include the ubiquitous PII superfamily of proteins and the CRP family protein NtcA, which in cyanobacteria functionally replaces the NtrB-NtrC system of enteric bacteria (reviewed in reference 2). Direct interaction with 2-OG increases the affinity of the NtcA transcriptional regulator for DNA targets and is necessary for initiation of transcription (3) and its interaction with PII frees PipX (4), which is thought to stabilize the active form of NtcA (5). NtcA regulates the expression of genes required for transformation of inorganic forms of nitrogen such as nitrate, nitrite, and dinitrogen into ammonia, as well as the developmental program of heterocystous cyanobacteria.Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that differentiates nitrogen-fixing heterocysts when a source of combined nitrogen is scarce (reviewed in references 6 and 7). During growth with a combined nitrogen source, usually ammonia or nitrate under laboratory conditions, Anabaena filaments are comprised exclusively of photosynthetic vegetative cells. When combined nitrogen is absent, however, a periodic pattern of morphologically distinct, nitrogen-fixing heterocyst cells is formed at approximately every 10th cell in the filament. The cascade of events involved in heterocyst differentiation can be divided into four phases: induction of differentiation, pattern formation, commitment to differentiation, and heterocyst maturation (8).The induction phase begins with ...

show abstract

Clustered genes required for synthesis and deposition of envelope glycolipids in Anabaena sp. strain PCC 7120

Cited by 93 publications

References 73 publications

The sigE Gene Is Required for Normal Expression of Heterocyst-Specific Genes in Anabaena sp. Strain PCC 7120

The sigE Gene Is Required for Normal Expression of Heterocyst-Specific Genes in Anabaena sp. Strain PCC 7120

The TolC-like Protein HgdD of the Cyanobacterium Anabaena sp. PCC 7120 Is Involved in Secondary Metabolite Export and Antibiotic Resistance

ThetrpEGene Negatively Regulates Differentiation of Heterocysts at the Level of Induction in Anabaena sp. Strain PCC 7120

Contact Info

Product

Resources

About