title: Tomato MBD5, a methyl CpG binding domain protein, physically interacting with UV-damaged DNA binding protein-1, functions in multiple processes.
abstract: In tomato (Solanum lycopersicum), high pigment mutations (hp-1 and hp-2) were mapped to genes encoding UV-damaged DNA binding protein 1 (DDB1) and de-etiolated-1 (DET1), respectively. Here we characterized a tomato methyl-CpG-binding domain protein SlMBD5 identified by yeast two-hybrid screening using SlDDB1 as a bait. Yeast two-hybrid assay demonstrated that the physical interaction of SlMBD5 with SlDDB1 is mediated by the C-termini of SlMBD5 and the β-propeller-C (BPC) of SlDDB1. Co-immunoprecipitation analyses revealed that SlMBD5 associates with SlDDB1-interacting partners including SlDET1, SlCUL4, SlRBX1a and SlRBX1b in vivo. SlMBD5 was shown to target to nucleus and dimerizes via its MBD motif. Electrophoresis mobility shift analysis suggested that the MBD of SlMBD5 specifically binds to methylated CpG dinucleotides but not to methylated CpHpG or CpHpH dinucleotides. SlMBD5 expressed in protoplast is capable of activating transcription of CG islands, whereas CUL4/DDB1 antagonizes this effect. Overexpressing SlMBD5 resulted in diverse developmental alterations including darker green fruits with increased plastid level and elevated pigmentation, as well as enhanced expression of SlGLK2, a key regulator of plastid biogenesis. Taken together, we hypothesize that the physical interaction of SlMBD5 with the CUL4-DDB1-DET1 complex component may affect its binding activity to methylated DNA and subsequently attenuate its transcription activation of downstream genes.
authors.affiliation: Ministry of education Key Laboratory for Bio-resource and Eco-environment, State key laboratory of Hydraulics and mountain River Engineering, College of Life Science, Sichuan University, Chengdu, 610064, China.
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Ministry of education Key Laboratory for Bio-resource and Eco-environment, State key laboratory of Hydraulics and mountain River Engineering, College of Life Science, Sichuan University, Chengdu, 610064, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Deng
authors.affiliation: School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, 230009, China.
authors.forename: Min
authors.initials: M
authors.lastname: Miao
authors.affiliation: Ministry of education Key Laboratory for Bio-resource and Eco-environment, State key laboratory of Hydraulics and mountain River Engineering, College of Life Science, Sichuan University, Chengdu, 610064, China.
authors.forename: Huirong
authors.initials: H
authors.lastname: Li
authors.affiliation: School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, 230009, China.
authors.forename: Shengxiong
authors.initials: S
authors.lastname: Huang
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
authors.forename: Songhu
authors.initials: S
authors.lastname: Wang
authors.affiliation: Ministry of education Key Laboratory for Bio-resource and Eco-environment, State key laboratory of Hydraulics and mountain River Engineering, College of Life Science, Sichuan University, Chengdu, 610064, China.|School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, 230009, China.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D018899:CpG Islands / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005638:Fruit / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D058685:Genetic Pleiotropy; D007976:Leupeptins / Q000494:pharmacology; D008027:Light; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D000070593:Methyl CpG Binding Domain; D010641:Phenotype; D010858:Pigmentation / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D063245:Plant Development / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000528:radiation effects; D055503:Protein Multimerization / Q000187:drug effects / Q000528:radiation effects; D055550:Protein Stability / Q000187:drug effects / Q000528:radiation effects; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects; D054875:Ubiquitination / Q000187:drug effects / Q000528:radiation effects
chemical_list: D004268:DNA-Binding Proteins; D007976:Leupeptins; D010940:Plant Proteins; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde
keywords: Cullin4 (CUL4); MBD; UV-damaged DNA binding protein 1 (DDB1); de-etiolated-1 (DET1); fruit quality; high pigment; plastid biogenesis; tomato (Solanum lycopersicum)