TM20, a Gene Coding for a New Class of Transmembrane Proteins Expressed in the Meristematic Tissues of Maize

Stiefel, Virginia; Becerra, Eduardo López; Roca, Ramón; Bastida, Miriam; Jahrmann, Torben; Graziano, Enrique; Puigdomènech, Pere

doi:10.1074/jbc.274.39.27734

Cited by 16 publications

(34 citation statements)

References 24 publications

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“…In the genome of Arabidopsis, despite their large number, PCMP genes are rarely clustered in tandems and therefore, recombination events between recently (not too divergent) duplicate motifs, either in the same gene or in recently reverse transcribed genes, have been probably lessened. One of the most attractive hypotheses for PCMP block duplication is the involvement of local microrecombinations as previously suggested for the formation of a gene coding for a maize (Zea mays) membrane protein, TM20, made of 20 hydrophobic domains that can be grouped in five homologous classes of four domains (Stiefel et al, 1999). For PCMPs as for membrane polypeptides, physicochemical properties or secondary structures are the direct object of selection rather than the amino acid sequence stricto sensu and, even in the exceptionally favorable case of TM20, the sequence divergence between different repeats largely obscured the evolutionary relationships between them.…”

Section: Resultsmentioning

confidence: 99%

Formation of the Arabidopsis Pentatricopeptide Repeat Family

Rivals

Bruyère²,

Toffano‐Nioche³

et al. 2006

Plant Physiology

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In Arabidopsis (Arabidopsis thaliana) the 466 pentatricopeptide repeat (PPR) proteins are putative RNA-binding proteins with essential roles in organelles. Roughly half of the PPR proteins form the plant combinatorial and modular protein (PCMP) subfamily, which is land-plant specific. PCMPs exhibit a large and variable tandem repeat of a standard pattern of three PPR variant motifs. The association or not of this repeat with three non-PPR motifs at their C terminus defines four distinct classes of PCMPs. The highly structured arrangement of these motifs and the similar repartition of these arrangements in the four classes suggest precise relationships between motif organization and substrate specificity. This study is an attempt to reconstruct an evolutionary scenario of the PCMP family. We developed an innovative approach based on comparisons of the proteins at two levels: namely the succession of motifs along the protein and the amino acid sequence of the motifs. It enabled us to infer evolutionary relationships between proteins as well as between the inter-and intraprotein repeats. First, we observed a polarized elongation of the repeat from the C terminus toward the N-terminal region, suggesting local recombinations of motifs. Second, the most N-terminal PPR triple motif proved to evolve under different constraints than the remaining repeat. Altogether, the evidence indicates different evolution for the PPR region and the C-terminal one in PCMPs, which points to distinct functions for these regions. Moreover, local sequence homogeneity observed across PCMP classes may be due to interclass shuffling of motifs, or to deletions/insertions of non-PPR motifs at the C terminus.

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Section: Resultsmentioning

confidence: 99%

Formation of the Arabidopsis Pentatricopeptide Repeat Family

Rivals

Bruyère²,

Toffano‐Nioche³

et al. 2006

Plant Physiology

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“…The characterization of empty pericarp (emp) mutants showed that loss of the negative regulator of the heat shock response Emp2 (Fu et al, 2002) or the mitochondriontargeted pentatricopeptide repeat protein Emp4 (Gutierrez-Marcos et al, 2007) affects both embryo and endosperm development. Lesions in the Cys proteinase Dek1 (Lid et al, 2002) cause a defective kernel (dek) phenotype similar to the one observed after loss of the transmembrane protein Lachrima (Stiefel et al, 1999). Finally, the analysis of etched (et) mutants indicated that the zinc ribbon protein Etched1 (da Costa e Silva et al, 2004) is needed to avoid fissures and cracks in the maize kernel.…”

mentioning

confidence: 99%

Transcriptional and Metabolic Adjustments in ADP-Glucose Pyrophosphorylase-Deficientbt2Maize Kernels

et al. 2008

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During the cloning of monogenic recessive mutations responsible for a defective kernel phenotype in a Mutator-induced Zea mays mutant collection, we isolated a new mutant allele in Brittle2 (Bt2), which codes for the small subunit of ADP-glucose pyrophosphorylase (AGPase), a key enzyme in starch synthesis. Reverse transcription-polymerase chain reaction experiments with gene-specific primers confirmed a predominant expression of Bt2 in endosperm, of Agpsemzm in embryo, and of Agpslzm in leaf, but also revealed considerable additional expression in various tissues for all three genes. Bt2a, the classical transcript coding for a cytoplasmic isoform, was almost exclusively expressed in the developing endosperm, whereas Bt2b, an alternative transcript coding for a plastidial isoform, was expressed in almost all tissues tested with a pattern very similar to that of Agpslzm. The phenotypic analysis showed that, at 30 d after pollination (DAP), mutant kernels were plumper than wild-type kernels, that the onset of kernel collapse took place between 31 and 35 DAP, and that the number of starch grains was greatly reduced in the mutant endosperm but not the mutant embryo. A comparative transcriptome analysis of wild-type and bt2-H2328 kernels at middevelopment (35 DAP) with the 18K GeneChip Maize Genome Array led to the conclusion that the lack of Bt2-encoded AGPase triggers large-scale changes on the transcriptional level that concern mainly genes involved in carbohydrate or amino acid metabolic pathways. Principal component analysis of 1H nuclear magnetic resonance metabolic profiles confirmed the impact of the bt2-H2328 mutation on these pathways and revealed that the bt2-H2328 mutation did not only affect the endosperm, but also the embryo at the metabolic level. These data suggest that, in the bt2-H2328 endosperms, regulatory networks are activated that redirect excess carbon into alternative biosynthetic pathways (amino acid synthesis) or into other tissues (embryo).

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“…Homologues of TaTM20 exist in Oryza sativa and Z. mays (30,44), but not in Arabidopsis, which indicates that this family of proteins is unique to monocotyledonous plants. Ectopic expression of TaTM20 in Arabidopsis had little effect on the tolerance to Cd(II) or accumulation of Cd(II) (data not shown).…”

Section: Discussionmentioning

confidence: 99%

“…Only one protein of the TM20 family, ZmTM20 in Z. mays, has been characterized to date. ZmTM20 is expressed during embryogenesis (30) and was shown to transport auxin when expressed in Xenopus oocytes (44). However, transport of auxin by ZmTM20 has not been demonstrated in planta.…”

Section: Discussionmentioning

confidence: 99%

“…TaTM20 encodes a novel gene (GenBank TM accession number DQ323065), based on examination of expressed sequence tags (ESTs) and cDNA sequences deposited in the GenBank TM data base. We screened the TIGR data base for homologues of TaTM20 in rice, and found that at the amino acid level TaTM20 has 24% identity and 33% similarity with ZmTM20 (dek34 embryogenesis protein) from Zea mays (30), and 26 -50% identity and 36 -60% similarity with 20 rice homologues. Phylogenetic tree shows that TaTM20 is a member of a gene family with many members exclusively from monocotyledonous plants (supplemental Fig.…”

Section: Isolation Of a Cd(ii)mentioning

confidence: 99%

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