The thanatos mutation in Arabidopsis thaliana cellulose synthase 3 (AtCesA3) has a dominant-negative effect on cellulose synthesis and plant growth.
Genetic functional analyses of mutants in plant genes encoding cellulose synthases (CesAs) have suggested that cellulose deposition requires the activity of multiple CesA proteins. Here, a genetic screen has led to the identification of thanatos (than), a semi-dominant mutant of Arabidopsis thaliana with impaired growth of seedlings. Homozygous seedlings of than germinate and grow but do not survive. In contrast to other CesA mutants, heterozygous plants are dwarfed and display a radially swollen root phenotype. Cellulose content is reduced by approximately one-fifth in heterozygous and by two-fifths in homozygous plants, showing gene-dosage dependence. Map-based cloning revealed an amino acid substitution (P578S) in the catalytic domain of the AtCesA3 gene, indicating a critical role for this residue in the structure and function of the cellulose synthase complex. Ab initio analysis of the AtCesA3 subdomain flanking the conserved proline residue predicted that the amino acid substitution to serine alters protein secondary structure in the catalytic domain. Gene dosage-dependent expression of the AtCesA3 mutant gene in wild-type A. thaliana plants resulted in a than dominant-negative phenotype. We propose that the incorporation of a mis-folded CesA3 subunit into the cellulose synthase complex may stall or prevent the formation of functional rosette complexes.
Daras
Gerasimos
G
Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, Athens 118 55, Greece.
Rigas
Stamatis
S
Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, Athens 118 55, Greece.
Penning
Bryan
B
Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA.
Milioni
Dimitra
D
Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, Athens 118 55, Greece.
McCann
Maureen C
MC
Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA.
Carpita
Nicholas C
NC
Department of Botany and Plant Pathology, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA.
Fasseas
Constantinos
C
Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, Athens 118 55, Greece.
Hatzopoulos
Polydefkis
P
Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, Athens 118 55, Greece.
D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D020134:Catalytic Domain; D002482:Cellulose / Q000096:biosynthesis*; D002874:Chromosome Mapping; D020090:Chromosome Segregation; D019295:Computational Biology; D017124:Conserved Sequence; D047108:Embryonic Development; D018628:Gene Dosage; D005799:Genes, Dominant; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D036226:Seedlings / Q000201:enzymology / Q000254:growth & development; D017550:Spectroscopy, Fourier Transform Infrared
D029681:Arabidopsis Proteins; D002482:Cellulose; C516179:At5g05170 protein, Arabidopsis; D005964:Glucosyltransferases