title: Molecular characterization of a novel gene family encoding ACT domain repeat proteins in Arabidopsis.
abstract: 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-beta-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.
authors.affiliation: Department of Genetics, Harvard Medical School, and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Ming-Hsiun
authors.initials: MH
authors.lastname: Hsieh
authors.forename: Howard M
authors.initials: HM
authors.lastname: Goodman
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D003080:Cold Temperature; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; D010937:Plant Growth Regulators; D011956:Receptors, Cell Surface; D012965:Sodium Chloride; C462019:ACR4 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D005966:Glucuronidase