A conserved arginine residue in a staphylococcal anti-sigma factor is required to preserve its kinase activity, structure, and stability

Sinha, Debasmita; Sinha, Debabrata; Banerjee, Nilanjan; Rai, Priya; Seal, Soham; Chakraborty, Tushar Kanti; Chatterjee, Subhrangsu; Sau, Subrata

doi:10.1080/07391102.2020.1864475

Cited by 7 publications

(3 citation statements)

References 51 publications

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“…Notably, both SipA and σ SsdA harbour an anti-sigma factor antagonist domain in their N-and C-terminal portions, respectively. Previous studies have shown that the anti-sigma factor RsbW dissociates from the cognate anti-anti-sigma factor RsbV by phosphorylating RsbV in B. subtilis (13,22). We postulate that binding between the anti-sigma factor and anti-sigma factor antagonist domains of SipA (both intramolecular and intermolecular interactions are possible) is weakened and strengthened by phosphorylation and dephosphorylation, respectively, of the N-terminal anti-sigma factor antagonist domain (Fig.…”

Section: Discussionmentioning

confidence: 80%

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A unique sigma/anti-sigma system involved in dormancy and revival of bacterial sporangiospores

Ohnishi,

Tezuka,

Mitsuyama

et al. 2023

Preprint

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Bacterial spores convert from dormant to active cells upon exposure to environmental stimuli; however, their molecular mechanisms remain unclear. Here, we report a unique sigma/anti-sigma system involved in the dormancy and revival of sporangiospores in the filamentous bacterium Actinoplanes missouriensis. We propose that the sigma factor σSsdA activates transcription of a subset of genes for the maintenance of dormancy, including the oxidative stress response, directly or indirectly in sporangiospores. The cognate anti-sigma factor SipA does not seem to be a switch for spore revival; rather, it seems to modulate σSsdA function to achieve appropriate transcription levels of σSsdA-dependent genes during and/or after sporangium formation. Both SipA and σSsdA possess an anti-sigma factor antagonist domain, thereby enabling interactions between the anti-sigma factor domain of SipA and the anti-sigma factor antagonist domain of σSsdA. We also identified a two-component regulatory system (RsdK-RsdR) indirectly activated by σSsdA as a key factor that represses revival of spores, more specifically, initiation of sporangium dehiscence. Thus, RsdK-RsdR plays a pivotal role in a molecular mechanism that delays the initiation of awakening of sporangiospores. This study reveals a previously unknown aspect of the general biological phenomena of cell dormancy and awakening.

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Section: Discussionmentioning

confidence: 80%

“…Conversely, in the absence of stressors, RsbW exerts kinase activity to phosphorylate RsbV and binds again to σ B . Therefore, σ B is modulated by the activities of the kinase RsbW and phosphatases RsbU and RsbP in this partner-switching regulatory system (13,22).…”

Section: Introductionmentioning

confidence: 99%

A unique sigma/anti-sigma system involved in dormancy and revival of bacterial sporangiospores

Ohnishi,

Tezuka,

Mitsuyama

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

A unique sigma/anti-sigma system in the actinomycete Actinoplanes missouriensis

Tezuka,

Mitsuyama,

Date

et al. 2023

Nat Commun

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Bacteria of the genus Actinoplanes form sporangia that contain dormant sporangiospores which, upon contact with water, release motile spores (zoospores) through a process called sporangium dehiscence. Here, we set out to study the molecular mechanisms behind sporangium dehiscence in Actinoplanes missouriensis and discover a sigma/anti-sigma system with unique features. Protein σSsdA contains a functional sigma factor domain and an anti-sigma factor antagonist domain, while protein SipA contains an anti-sigma factor domain and an anti-sigma factor antagonist domain. Remarkably, the two proteins interact with each other via the anti-sigma factor antagonist domain of σSsdA and the anti-sigma factor domain of SipA. Although it remains unclear whether the SipA/σSsdA system plays direct roles in sporangium dehiscence, the system seems to modulate oxidative stress responses in zoospores. In addition, we identify a two-component regulatory system (RsdK-RsdR) that represses initiation of sporangium dehiscence.

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Computational assessment of saikosaponins as adjuvant treatment for COVID-19: molecular docking, dynamics, and network pharmacology analysis

et al. 2021

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Saikosaponins are major biologically active triterpenoids, usually as glucosides, isolated from Traditional Chinese Medicines (TCM) such as Bupleurum spp., Heteromorpha spp., and Scrophularia scorodonia with their antiviral and immunomodulatory potential. This investigation presents molecular docking, molecular dynamics simulation, and free energy calculation studies of saikosaponins as adjuvant therapy in the treatment for COVID19. Molecular docking studies for 23 saikosaponins on the crystal structures of the extracellular domains of human lnterleukin-6 receptor (IL6), human Janus Kinase-3 (JAK3), and dehydrogenase domain of Cylindrospermum stagnale NADPH-oxidase 5 (NOX5) were performed, and selected protein-ligand complexes were subjected to 100 ns molecular dynamics simulations. The molecular dynamics trajectories were subjected to free energy calculation by the MM-GBSA method. Molecular docking and molecular dynamics simulation studies revealed that IL6 in complex with Saikosaponin_U and Saikosaponin_V, JAK3 in complex with Saikosaponin_B4 and Saikosaponin_I, and NOX5 in complex with Saikosaponin_BK1 and Saikosaponin_C have good docking and molecular dynamics profiles. However, the Janus Kinase-3 is the best interacting partner for the saikosaponin compounds. The network pharmacology analysis suggests saikosaponins interact with the proteins CAT Gene CAT (Catalase) and Checkpoint kinase 1 (CHEK1); both of these enzymes play a major role in cell homeostasis and DNA damage during infection, suggesting a possible improvement in immune response toward COVID-19.Rupesh Chikhale, Saurabh Sinha and Manish Wanjari have contributed equally to this work and are treated as first authors.

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A conserved arginine residue in a staphylococcal anti-sigma factor is required to preserve its kinase activity, structure, and stability

Cited by 7 publications

References 51 publications

A unique sigma/anti-sigma system involved in dormancy and revival of bacterial sporangiospores

A unique sigma/anti-sigma system involved in dormancy and revival of bacterial sporangiospores

A unique sigma/anti-sigma system in the actinomycete Actinoplanes missouriensis

Computational assessment of saikosaponins as adjuvant treatment for COVID-19: molecular docking, dynamics, and network pharmacology analysis

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