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Loss of Biliverdin Reductase Increases Oxidative Stress in the Cyanobacterium Synechococcus sp. PCC 7002.
Schluchter, Wendy M; Babin, Courtney H; Liu, Xindi; Bieller, Amori; Shen, Gaozhong; Alvey, Richard M; Bryant, Donald A.
Afiliación
  • Schluchter WM; Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA.
  • Babin CH; Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA.
  • Liu X; Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA.
  • Bieller A; Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA.
  • Shen G; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
  • Alvey RM; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
  • Bryant DA; Biology Department, Bloomington, Illinois Wesleyan University, Bloomington, IL 61702, USA.
Microorganisms ; 11(10)2023 Oct 20.
Article en En | MEDLINE | ID: mdl-37894251
Oxygenic photosynthesis requires metal-rich cofactors and electron-transfer components that can produce reactive oxygen species (ROS) that are highly toxic to cyanobacterial cells. Biliverdin reductase (BvdR) reduces biliverdin IXα to bilirubin, which is a potent scavenger of radicals and ROS. The enzyme is widespread in mammals but is also found in many cyanobacteria. We show that a previously described bvdR mutant of Synechocystis sp. PCC 6803 contained a secondary deletion mutation in the cpcB gene. The bvdR gene from Synechococcus sp. PCC 7002 was expressed in Escherichia coli, and recombinant BvdR was purified and shown to reduce biliverdin to bilirubin. The bvdR gene was successfully inactivated in Synechococcus sp. PCC 7002, a strain that is naturally much more tolerant of high light and ROS than Synechocystis sp. PCC 6803. The bvdR mutant strain, BR2, had lower total phycobiliprotein and chlorophyll levels than wild-type cells. As determined using whole-cell fluorescence at 77 K, the photosystem I levels were also lower than those in wild-type cells. The BR2 mutant had significantly higher ROS levels compared to wild-type cells after exposure to high light for 30 min. Together, these results suggest that bilirubin plays an important role as a scavenger for ROS in Synechococcus sp. PCC 7002. The oxidation of bilirubin by ROS could convert bilirubin to biliverdin IXα, and thus BvdR might be important for regenerating bilirubin. These results further suggest that BvdR is a key component of a scavenging cycle by which cyanobacteria protect themselves from the toxic ROS byproducts generated during oxygenic photosynthesis.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Microorganisms Año: 2023 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Suiza
Texto completo
Añadir a Mi BVS
Imprimir
XML
PubMed Links
Buscar en Google

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Microorganisms Año: 2023 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Suiza