NMAT4, a maturase factor required for nad1 pre‐mRNA processing and maturation, is essential for holocomplex I biogenesis in Arabidopsis mitochondria. (26th March 2014)

• Record Type: Journal Article
• Authors: Cohen, Sigal; Zmudjak, Michal; Colas des Francs‐Small, Catherine; Malik, Sunita; Shaya, Felix; Keren, Ido; Belausov, Eduard; Many, Yair; Brown, Gregory G.; Small, Ian; Ostersetzer‐Biran, Oren
• Is Part Of: Plant journal. Volume 78:Number 2(2014:Apr.)
• Page Start: 253
• Page End: 268
• Publication Date: 2014-03-26
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12466
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12466-abs-0001"> <title>Summary</title> <p>Group II introns are large catalytic RNAs that are found in bacteria and organellar genomes of lower eukaryotes, but are particularly prevalent within mitochondria in plants, where they are present in many critical genes. The excision of plant mitochondrial introns is essential for respiratory functions, and is facilitated <italic>in vivo</italic> by various protein cofactors. Typical group II introns are classified as mobile genetic elements, consisting of the self‐splicing ribozyme and its own intron‐encoded maturase protein. A hallmark of maturases is that they are intron‐specific, acting as cofactors that bind their intron‐containing pre‐RNAs to facilitate splicing. However, the degeneracy of the mitochondrial introns in plants and the absence of cognate intron‐encoded maturase open reading frames suggest that their splicing <italic>in vivo</italic> is assisted by '<italic>trans</italic>'‐acting protein factors. Interestingly, angiosperms harbor several nuclear‐encoded maturase‐related (<italic>nMat</italic>) genes that contain N‐terminal mitochondrial localization signals. Recently, we established the roles of two of these paralogs in Arabidopsis, nMAT1 and nMAT2, in the splicing of mitochondrial introns. Here we show that nMAT4 (At1g74350) is required for RNA processing and maturation of <italic>nad1</italic> introns 1, 3 and 4 in Arabidopsis mitochondria. Seed germination, seedling establishment and development are strongly affected in homozygous <italic>nmat4</italic> mutants, which also show modified respiration phenotypes that are tightly associated with complex I defects.</p> </abstract>