Protein Geranylgeranyltransferase I Is Involved in Specific Aspects of Abscisic Acid and Auxin Signaling in Arabidopsis

• Published in: Plant physiology (Bethesda) Vol. 139; no. 2; pp. 722 - 733
• Main Authors: Johnson, Cynthia D, Chary, S. Narasimha, Chernoff, Ellen A, Zeng, Qin, Running, Mark P, Crowell, Dring N
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.10.2005; American Society of Plant Physiologists
• Subjects: abscisic acid; Abscisic Acid - metabolism; Abscisic Acid - pharmacology; alkyl (aryl) transferases; Alkyl and Aryl Transferases - genetics; Alkyl and Aryl Transferases - metabolism; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Auxins; Base Sequence; Biological and medical sciences; Cell physiology; Development and Hormone Action; DNA, Bacterial - genetics; DNA, Plant - genetics; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Gene Targeting; Genes, Plant; Germination - drug effects; Guard cells; Indoleacetic Acids - metabolism; insertional mutagenesis; Molecular and cellular biology; Molecular Sequence Data; Mutagenesis, Insertional; Mutation; nucleotide sequences; Phenotype; Phenotypes; phenotypic variation; plant biochemistry; Plant cells; plant genetics; plant growth; Plant growth regulators; plant morphology; plant physiology; plant proteins; Plants; Polymerase chain reaction; protein geranylgeranyltransferase; Proteins; Pulmonary function tests; rooting; seed germination; Signal transduction; Signal Transduction - physiology; stomata; transfer DNA; transgenic plants; Auxin; Seeds; Root; Enzyme; Growth; Transferases; Germination; Stomata; Farnesyl-diphosphate farnesyltransferase; Guard cell; Meristem; Arabidopsis thaliana; Gene; Cruciferae; Dicotyledones; Angiospermae; Abscisic acid; Development; Spermatophyta; Inhibition; Mutation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.105.065045

Arabidopsis (Arabidopsis thaliana) mutants lacking a functional ERA1 gene, which encodes the [beta]-subunit of protein farnesyltransferase (PFT), exhibit pleiotropic effects that establish roles for protein prenylation in abscisic acid (ABA) signaling and meristem development. Here, we report the effects of T-DNA insertion mutations in the Arabidopsis GGB gene, which encodes the [beta]-subunit of protein geranylgeranyltransferase type I (PGGT I). Stomatal apertures of ggb plants were smaller than those of wild-type plants at all concentrations of ABA tested, suggesting that PGGT I negatively regulates ABA signaling in guard cells. However, germination of ggb seeds in response to ABA was similar to the wild type. Lateral root formation in response to exogenous auxin was increased in ggb seedlings compared to the wild type, but no change in auxin inhibition of primary root growth was observed, suggesting that PGGT I is specifically involved in negative regulation of auxin-induced lateral root initiation. Unlike era1 mutants, ggb mutants exhibited no obvious developmental phenotypes. However, era1 ggb double mutants exhibited more severe developmental phenotypes than era1 mutants and were indistinguishable from plp mutants lacking the shared [alpha]-subunit of PFT and PGGT I. Furthermore, overexpression of GGB in transgenic era1 plants partially suppressed the era1 phenotype, suggesting that the relatively weak phenotype of era1 plants is due to partial redundancy between PFT and PGGT I. These results are discussed in the context of Arabidopsis proteins that are putative substrates of PGGT I.