Molecular Characterization of a Novel Gene Family Encoding ACT Domain Repeat Proteins in Arabidopsis

• Published in: Plant physiology (Bethesda) 2002-12, Vol.130 (4), p.1797-1806
• Main Authors: Hsieh, Ming-Hsiun, Goodman, Howard M.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Amino acid metabolism; Amino Acid Sequence; Amino acids; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell biochemistry; Cell Biology and Signal Transduction; Cell physiology; Chromosome Mapping; Chromosomes; Cold Temperature; Complementary DNA; Darkness; DNA, Complementary - chemistry; DNA, Complementary - genetics; Enzymes; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - drug effects; Genes; Genes. Genome; Glucuronidase - genetics; Glucuronidase - metabolism; Hormones; Light; Messenger RNA; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Multigene Family - genetics; Plant Growth Regulators - pharmacology; Plant physiology and development; Plants; Plants, Genetically Modified; Promoter Regions, Genetic - genetics; Protein-Serine-Threonine Kinases; Proteins; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Seedlings; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Sodium Chloride - pharmacology; Standardized tests
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.007484

In bacteria, the regulatory ACT domains serve as amino acid-binding sites in some feedback-regulated amino acid metabolic enzymes. We have identified a novel type of ACT domain-containing protein family in Arabidopsis whose members contain ACT domain repeats (the "ACR" protein family). There are at least eight ACR genes located on each of the five chromosomes in the Arabidopsis genome. Gene structure comparisons indicate that the ACR gene family may have arisen by gene duplications. Northern-blot analysis indicates that each member of the ACR gene family has a distinct expression pattern in various organs from 6-week-old Arabidopsis. Moreover, analyses of an ACR3 promoter-β-glucuronidase (GUS) fusion in transgenic Arabidopsis revealed that the GUS activity formed a gradient in the developing leaves and sepals, whereas low or no GUS activity was detected in the basal regions. In 2-week-old Arabidopsis seedlings grown in tissue culture, the expression of the ACR gene family is differentially regulated by plant hormones, salt stress, cold stress, and light/dark treatment. The steady-state levels of ACR8 mRNA are dramatically increased by treatment with abscisic acid or salt. Levels of ACR3 and ACR4 mRNA are increased by treatment with benzyladenine. The amino acid sequences of Arabidopsis ACR proteins are most similar in the ACT domains to the bacterial sensor protein GlnD. The ACR proteins may function as novel regulatory or sensor proteins in plants.