The SLOW GROWTH3 Pentatricopeptide Repeat Protein Is Required for the Splicing of Mitochondrial NADH Dehydrogenase Subunit7 Intron 2 in Arabidopsis

Plant Physiol. 2015 Jun;168(2):490-501. doi: 10.1104/pp.15.00354. Epub 2015 Apr 17.


Mitochondria play an important role in maintaining metabolic and energy homeostasis in the cell. In plants, impairment in mitochondrial functions usually has detrimental effects on growth and development. To study genes that are important for plant growth, we have isolated a collection of slow growth (slo) mutants in Arabidopsis (Arabidopsis thaliana). One of the slo mutants, slo3, has a significant reduction in mitochondrial complex I activity. The slo3 mutant has a four-nucleotide deletion in At3g61360 that encodes a pentatricopeptide repeat (PPR) protein. The SLO3 protein contains nine classic PPR domains belonging to the P subfamily. The small deletion in the slo3 mutant changes the reading frame and creates a premature stop codon in the first PPR domain. We demonstrated that the SLO3-GFP is localized to the mitochondrion. Further analysis of mitochondrial RNA metabolism revealed that the slo3 mutant was defective in splicing of NADH dehydrogenase subunit7 (nad7) intron 2. This specific splicing defect led to a dramatic reduction in complex I activity in the mutant as revealed by blue native gel analysis. Complementation of slo3 by 35S:SLO3 or 35S:SLO3-GFP restored the splicing of nad7 intron 2, the complex I activity, and the growth defects of the mutant. Together, these results indicate that the SLO3 PPR protein is a splicing factor of nad7 intron 2 in Arabidopsis mitochondria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / cytology
  • Arabidopsis / enzymology
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Cell Proliferation
  • DNA, Complementary / genetics
  • Electron Transport Complex I / metabolism
  • Genes, Plant
  • Genetic Complementation Test
  • Green Fluorescent Proteins / metabolism
  • Introns / genetics*
  • Mitochondria / enzymology*
  • Mitochondrial Proteins / chemistry
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism*
  • Molecular Sequence Data
  • Mutation / genetics
  • NADH Dehydrogenase / genetics*
  • NADH Dehydrogenase / metabolism
  • Phenotype
  • Plant Roots
  • Protein Transport
  • RNA Editing
  • RNA Splicing / genetics*
  • RNA Splicing Factors
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Repetitive Sequences, Amino Acid*
  • Seedlings / metabolism


  • Arabidopsis Proteins
  • DNA, Complementary
  • Mitochondrial Proteins
  • RNA Splicing Factors
  • RNA, Messenger
  • SLO3 protein, Arabidopsis
  • Green Fluorescent Proteins
  • NAD7 protein, Arabidopsis
  • NADH Dehydrogenase
  • Electron Transport Complex I

Associated data

  • GENBANK/AFW69255
  • GENBANK/ERP64851
  • RefSeq/NM_116000
  • RefSeq/NP_001058444
  • RefSeq/XP_002282912
  • RefSeq/XP_002438925
  • RefSeq/XP_003554843
  • RefSeq/XP_004237781