Dataset Information

Comparison of expression profiles for Agrobacterium tumefaciens wild-type strain C58 and isogenic pdhS2 (Atu1888) deletion strain

ABSTRACT: A conserved regulatory pathway directs developmental transitions and asymmetries in Agrobacterium tumefaciens. Core components of this coordination of division and development (CDD) pathway include two integrated phosphorelays. One of these phosphorelays includes at least four histidine sensor kinase homologues, DivJ, PleC, PdhS1, and PdhS2, and at least two response regulators, DivK and PleD. Previously we demonstrated that PdhS2 reciprocally regulates biofilm formation and swimming motility. In the current study we further dissect the architecture of the CDD pathway in A. tumefaciens with respect to PdhS2. We show that PdhS2-dependent effects on attachment and motility require the response regulator, DivK, but do not require PdhS2 autokinase or phosphotransfer activities. We also demonstrate that PdhS2 regulation of biofilm formation is dependent upon multiple diguanylate cyclases, including PleD, DgcA, and DgcB, implying that PdhS2 regulation of this process intersects with pathways regulating levels of the second messenger cyclic-di-GMP. Finally, we show that upon cell division a GFP fusion to PdhS2 dynamically localizes to the new pole of the bacterium suggesting that PdhS2 controls processes in the daughter cell compartment of predivisional cells. These observations suggest that PdhS2 negatively regulates DivK, and possibly PleD, activity to control developmental processes in the daughter cell compartment of predivisional cells, as well as in newly released motile daughter cells.

ORGANISM(S): Agrobacterium tumefaciens

PROVIDER: GSE71267 | GEO | 2015/07/24

SECONDARY ACCESSION(S): PRJNA290727

REPOSITORIES: GEO

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Project description:Alphaproteobacteria stand out for their complex cell cycles, which are often regulated by the DivJ/PleC-DivK-DivL-CckA-ChpT-CtrA pathway. DivJ and PleC set up the polarity of the cell, thereby eventually leading to differential activation of the DNA-binding response regulator CtrA in the two nascent daughter cells. CtrA regulates replication and transcription of many genes, thereby ensuring that processes such as motility and cell division take place at the appropriate cell cycle stage. The cell cycle of the stalked budding alphaproteobacterium Hyphomonas neptunium culminates in an asymmetric cell division at the stalk-bud junction. Here, we investigate the role of the pathway from DivJ and PleC down to CtrA in this recently established model organism. Even though DivJ and PleC are localized to opposite poles, suggesting they are involved in polarity establishment inH. neptunium, DivJ, PleC and the other components of the upstream pathway (DivK and PleD) are not essential for cell cycle regulation. In contrast, the downstream part of the pathway starting from DivL is essential and involved in the regulation of important functions such as replication inhibition, cell division and motility, as shown by the identification of the (direct) regulon of CtrA. The overlap between the regulons of DivJ and PleC, DivK and CtrA is only partial, demonstrating that additional factors feeding into the pathway must be present in H. neptunium. Furthermore, unlike in other alphaproteobacteria, the regulation of CtrA throughout the cell cycle does not take place at the level of CtrA abundance in H. neptunium. All in all, the DivL-CckA-ChpT-CtrA pathway plays an essential role in the regulation of the complicated cell cycle ofH. neptunium, but several proteins feeding into CtrA remain undiscovered. The in-depth analysis of CtrA regulation in this stalked budding organism leads to hypotheses that might also hold in well-established model organisms such as Caulobacter crescentus.

Dataset Information

Comparison of expression profiles for Agrobacterium tumefaciens wild-type strain C58 and isogenic pdhS2 (Atu1888) deletion strain

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