2026-06-14T03:40:27Zhttps://repisalud.isciii.es/rest/oai/request

oai:repisalud.isciii.es:20.500.12105/160962025-05-08T13:09:44Zcom_20.500.12105_2052com_20.500.12105_2051col_20.500.12105_19609col_20.500.12105_25179

00925njm 22002777a 4500 dc de Vasconcelos Júnior, Antônio Alexandre author Tirado-Velez, JM author Martin-Galiano, Antonio Javier author Megías, Diego author Ferrandiz-Avellano, Maria-Jose author Hernández, Pablo author Amblar, Monica author de la Campa, Adela G author 2023-03-22 The DNA topoisomerases gyrase and topoisomerase I as well as the nucleoid-associated protein HU maintain supercoiling levels in Streptococcus pneumoniae, a main human pathogen. Here, we characterized, for the first time, a topoisomerase I regulator protein (StaR). In the presence of sub-inhibitory novobiocin concentrations, which inhibit gyrase activity, higher doubling times were observed in a strain lacking staR, and in two strains in which StaR was over-expressed either under the control of the ZnSO4-inducible PZn promoter (strain ΔstaRPZnstaR) or of the maltose-inducible PMal promoter (strain ΔstaRpLS1ROMstaR). These results suggest that StaR has a direct role in novobiocin susceptibility and that the StaR level needs to be maintained within a narrow range. Treatment of ΔstaRPZnstaR with inhibitory novobiocin concentrations resulted in a change of the negative DNA supercoiling density (σ) in vivo, which was higher in the absence of StaR (σ = -0.049) than when StaR was overproduced (σ = -0.045). We have located this protein in the nucleoid by using super-resolution confocal microscopy. Through in vitro activity assays, we demonstrated that StaR stimulates TopoI relaxation activity, while it has no effect on gyrase activity. Interaction between TopoI and StaR was detected both in vitro and in vivo by co-immunoprecipitation. No alteration of the transcriptome was associated with StaR amount variation. The results suggest that StaR is a new streptococcal nucleoid-associated protein that activates topoisomerase I activity by direct protein-protein interaction. Int J Mol Sci. 2023 Mar 22;24(6):5973. 10.3390/ijms24065973 1422-0067 International journal of molecular sciences 36983048 http://hdl.handle.net/20.500.12105/16096 DNA gyrase DNA supercoiling DNA topoisomerase I StaR Nucleoid-associated proteins Supercoiling homeostasis Supercoiling regulation Topsoisomerase regulator StaR Is a Positive Regulator of Topoisomerase I Activity Involved in Supercoiling Maintenance in Streptococcus pneumoniae