title: Identification of Rbd2 as a candidate protease for sterol regulatory element binding protein (SREBP) cleavage in fission yeast.
abstract: Lipid homeostasis in mammalian cells is regulated by sterol regulatory element-binding protein (SREBP) transcription factors that are activated through sequential cleavage by Golgi Site-1 and Site-2 proteases. Fission yeast SREBP, Sre1, engages a different mechanism involving the Golgi Dsc E3 ligase complex, but it is not clearly understood exactly how Sre1 is proteolytically cleaved and activated. In this study, we screened the Schizosaccharomyces pombe non-essential haploid deletion collection to identify missing components of the Sre1 cleavage machinery. Our screen identified an additional component of the SREBP pathway required for Sre1 proteolysis named rhomboid protein 2 (Rbd2). We show that an rbd2 deletion mutant fails to grow under hypoxic and hypoxia-mimetic conditions due to lack of Sre1 activity and that this growth phenotype is rescued by Sre1N, a cleaved active form of Sre1. We found that the growth inhibition phenotype under low oxygen conditions is specific to the strain with deletion of rbd2, not any other fission yeast rhomboid-encoding genes. Our study also identified conserved residues of Rbd2 that are required for Sre1 proteolytic cleavage. All together, our results suggest that Rbd2 is a functional SREBP protease with conserved residues required for Sre1 cleavage and provide an important piece of the puzzle to understand the mechanisms for Sre1 activation and the regulation of various biological and pathological processes involving SREBPs.
authors.affiliation: Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Jinsil
authors.initials: J
authors.lastname: Kim
authors.affiliation: Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Hye-Jeong
authors.initials: HJ
authors.lastname: Ha
authors.affiliation: Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Functional Genomics, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Sujin
authors.initials: S
authors.lastname: Kim
authors.affiliation: Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Ah-Reum
authors.initials: AR
authors.lastname: Choi
authors.affiliation: Department of New Drug Discovery and Development, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea.
authors.forename: Sook-Jeong
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of New Drug Discovery and Development, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea. Electronic address: kwanghoe@cnu.ac.kr.
authors.forename: Kwang-Lae
authors.initials: KL
authors.lastname: Hoe
authors.affiliation: Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea. Electronic address: kimdongu@kribb.re.kr.
authors.forename: Dong-Uk
authors.initials: DU
authors.lastname: Kim
mesh_terms: D001665:Binding Sites; D049109:Cell Proliferation / Q000502:physiology; D004789:Enzyme Activation; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000502:physiology*; D012568:Schizosaccharomyces / Q000378:metabolism*; D051779:Sterol Regulatory Element Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D051779:Sterol Regulatory Element Binding Proteins; D010447:Peptide Hydrolases; C000604520:Rbd2 protein, S cerevisiae; D010100:Oxygen
keywords: Hypoxia; Lipid homeostasis; Rbd2; SREBP; Schizosaccharomyces pombe; Sre1