Expression from DIF1-motif promoters of hetR and patS is dependent on HetZ and modulated by PatU3 during heterocyst differentiation

Du, Yaru; Zhang, He; Wang, Hong; Wang, Shuai; Lei, Qiqin; Li, Chao; Kong, Renqiu; Xu, Xudong

doi:10.1371/journal.pone.0232383

“…This delay could be related to the mechanism of commitment to the differentiation of a given cell. In our model, this decision is exclusively linked to a sustained high concentration of HetR and not to the expression of a supplementary gene ( hetP and/or hetZ ) as recent publications [ 76 – 81 ] seem to indicate. Hence, incorporating a gene-controlled differentiation commitment would surely improve these results, because then self-regulation of that gene could amplify the differentiation signal.…”

Section: Resultsmentioning

confidence: 82%

Terminal heterocyst differentiation in the Anabaena patA mutant as a result of post-transcriptional modifications and molecular leakage

Casanova-Ferrer

¹

,

Ares

²

,

Muñoz-García

³

2022

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The Anabaena genus is a model organism of filamentous cyanobacteria whose vegetative cells can differentiate under nitrogen-limited conditions into a type of cell called heterocyst. These heterocysts lose the possibility to divide and are necessary for the colony because they can fix and share environmental nitrogen. In order to distribute the nitrogen efficiently, heterocysts are arranged to form a quasi-regular pattern whose features are maintained as the filament grows. Recent efforts have allowed advances in the understanding of the interactions and genetic mechanisms underlying this dynamic pattern. However, the main role of the patA and hetF genes are yet to be clarified; in particular, the patA mutant forms heterocysts almost exclusively in the terminal cells of the filament. In this work, we investigate the function of these genes and provide a theoretical model that explains how they interact within the broader genetic network, reproducing their knock-out phenotypes in several genetic backgrounds, including a nearly uniform concentration of HetR along the filament for the patA mutant. Our results suggest a role of hetF and patA in a post-transcriptional modification of HetR which is essential for its regulatory function. In addition, the existence of molecular leakage out of the filament in its boundary cells is enough to explain the preferential appearance of terminal heterocysts, without any need for a distinct regulatory pathway.

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“…This delay could be related to the mechanism of commitment to the differentiation of a given cell. In our model, this decision is exclusively linked to a sustained high concentration of HetR and not to the expression of a supplementary gene (hetP and/or hetZ ) as recent publications [60,61,[81][82][83][84] seem to indicate. Hence, incorporating a gene-controlled differentiation commitment would surely improve these results, because then self-regulation of that gene could amplify the differentiation signal.…”

Section: Study Of the Wild-type And The ∆Pats And ∆Hetn Mutantsmentioning

confidence: 80%

Terminal heterocyst differentiation in the Anabaena patA mutant as a result of post-transcriptional modifications and molecular leakage

Casanova-Ferrer

¹

,

Ares

²

,

Muñoz-García

³

2021

Preprint

0

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The Anabaena genus is a model organism of filamentous cyanobacteria whose vegetative cells can differentiate under nitrogen-limited conditions into a type of cell called heterocyst. These heterocysts lose the possibility to divide and are necessary for the colony because they can fix and share environmental nitrogen. In order to distribute the nitrogen efficiently, heterocysts are arranged to form a quasi-regular pattern whose features are maintained as the filament grows. Recent efforts have allowed advances in the understanding of the interactions and genetic mechanisms underlying this dynamic pattern. However, the main role of the patA and hetF genes are yet to be clarified; in particular, the patA mutant forms heterocysts almost exclusively in the terminal cells of the filament. In this work, we investigate the function of these genes and provide a theoretical model that explains how they interact within the broader genetic network, reproducing their knock-out phenotypes in several genetic backgrounds, including a nearly uniform concentration of HetR along the filament for the patA mutant. Our results suggest a role of hetF and patA in a post-transcriptional modification of HetR which is essential for its regulatory function. In addition, the existence of molecular leakage out of the filament in its boundary cells is enough to explain the preferential appearance of terminal heterocysts, without any need for a distinct regulatory pathway.

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“…PCC 7120 is used as reference. The final list of searched multicellular genes included the fra cluster sepJ ( fraG ; alr2338 ), fraE ( alr2394 ), fraC ( alr2392 ), fraD ( alr2393 ) and fraH ( alr1603 ) [ 33 , 34 , 35 , 36 , 37 , 38 ]; the amiC operon genes amiC1 ( alr0092 ), amiC2 ( alr0093 ) and murI ( alr0094 ) [ 39 , 40 , 41 ]; the mur operon murB ( alr5066 ) and murC ( alr5065 ) [ 42 ]; mreB ( all0087 ), mreC ( all0086 ), mreD ( all0085 ) [ 43 ], mdrA ( alr5045 ) and alr2270 [ 44 ]; cydiv ( all2320 ) [ 45 ]; and hetR ( alr2339 ), patU3 ( alr0101 ) and hetZ ( alr0099 ) [ 46 ]. Multicellularity genes listed in Figure 1 were screened using the BLASTp algorithm and each respective gene from Nostoc sp.…”

Section: Methodsmentioning

confidence: 99%

Final Destination? Pinpointing Hyella disjuncta sp. nov. PCC 6712 (Cyanobacteria) Based on Taxonomic Aspects, Multicellularity, Nitrogen Fixation and Biosynthetic Gene Clusters

Jung

¹

,

D’Agostino

²

,

Brust

³

et al. 2021

Life

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Unicellular cyanobacteria inhabit a wide range of ecosytems and can be found throughout the phylum offering space for taxonomic confusion. One example is strain PCC 6712 that was described as Chlorogloea sp. (Nostocales) and later assigned to the genus Chroococcidiopsis (Chroococcidiopsidales). We now show that this strain belongs to the order Pleurocapsales and term it Hyella disjuncta based on morphology, genome analyses and 16S-23S ITS rRNA phylogeny. Genomic analysis indicated that H. disjuncta PCC 6712 shared about 44.7% orthologue genes with its closest relative H. patelloides. Furthermore, 12 cryptic biosynthetic gene clusters (BGCs) with potential bioactivity, such as a mycosporine-like amino acid BGC, were detected. Interestingly, the full set of nitrogen fixation genes was found in H. disjuncta PCC 6712 despite its inability to grow on nitrogen-free medium. A comparison of genes responsible for multicellularity was performed, indicating that most of these genes were present and related to those found in other cyanobacterial orders. This is in contrast to the formation of pseudofilaments—a main feature of the genus Hyella—which is weakly expressed in H. disjuncta PCC 6712 but prominent in Hyella patelloides LEGE 07179. Thus, our study pinpoints crucial but hidden aspects of polyphasic cyanobacterial taxonomy.

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Expression from DIF1-motif promoters of hetR and patS is dependent on HetZ and modulated by PatU3 during heterocyst differentiation

Cited by 11 publications

References 51 publications

Terminal heterocyst differentiation in the Anabaena patA mutant as a result of post-transcriptional modifications and molecular leakage

Terminal heterocyst differentiation in the Anabaena patA mutant as a result of post-transcriptional modifications and molecular leakage

Terminal heterocyst differentiation in the Anabaena patA mutant as a result of post-transcriptional modifications and molecular leakage

Final Destination? Pinpointing Hyella disjuncta sp. nov. PCC 6712 (Cyanobacteria) Based on Taxonomic Aspects, Multicellularity, Nitrogen Fixation and Biosynthetic Gene Clusters

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