nMAT1, a nuclear-encoded maturase involved in the trans-splicing of nad1 intron 1, is essential for mitochondrial complex I assembly and function

Plant J. 2012 Aug;71(3):413-26. doi: 10.1111/j.1365-313X.2012.04998.x. Epub 2012 May 22.


Mitochondrial genomes (mtDNAs) in angiosperms contain numerous group II-type introns that reside mainly within protein-coding genes that are required for organellar genome expression and respiration. While splicing of group II introns in non-plant systems is facilitated by proteins encoded within the introns themselves (maturases), the mitochondrial introns in plants have diverged and have lost the vast majority of their intron-encoded ORFs. Only a single maturase gene (matR) is retained in plant mtDNAs, but its role(s) in the splicing of mitochondrial introns is currently unknown. In addition to matR, plants also harbor four nuclear maturase genes (nMat 1 to 4) encoding mitochondrial proteins that are expected to act in the splicing of group II introns. Recently, we established the role of one of these proteins, nMAT2, in the splicing of several mitochondrial introns in Arabidopsis. Here, we show that nMAT1 is required for trans-splicing of nad1 intron 1 and also functions in cis-splicing of nad2 intron 1 and nad4 intron 2. Homozygous nMat1 plants show retarded growth and developmental phenotypes, modified respiration activities and altered stress responses that are tightly correlated with mitochondrial complex I defects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis / physiology
  • Arabidopsis / ultrastructure
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Cell Nucleus / genetics
  • Cell Respiration
  • Gene Expression Regulation, Plant / genetics*
  • Gene Knockout Techniques
  • Introns / genetics
  • Metabolome
  • Mitochondria / metabolism*
  • Mitochondrial Proteins / genetics
  • Mutation
  • Nucleotidyltransferases / genetics
  • Nucleotidyltransferases / metabolism*
  • Phenotype
  • RNA / genetics
  • RNA, Mitochondrial
  • RNA, Plant / genetics
  • RNA-Directed DNA Polymerase / genetics
  • RNA-Directed DNA Polymerase / metabolism
  • Reactive Oxygen Species / metabolism
  • Stress, Physiological / physiology
  • Trans-Splicing / genetics*


  • Arabidopsis Proteins
  • Mitochondrial Proteins
  • RNA, Mitochondrial
  • RNA, Plant
  • Reactive Oxygen Species
  • RNA
  • Nucleotidyltransferases
  • mat1 maturase
  • RNA-Directed DNA Polymerase
  • nMat1a protein, Arabidopsis