Characterization of regions within the n-terminal 6-kilodalton domain of phytochrome A that modulate its biological activity

• Published in: Plant physiology (Bethesda) Vol. 115; no. 2; pp. 693 - 704
• Main Authors: Jordan, E.T, Marita, J.M, Clough, R.C, Vierstra, R.D
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.10.1997
• Subjects: ALANINA; ALANINE; Alanine - genetics; Amino Acid Sequence; AMINO ACID SEQUENCES; Amino acids; APOPROTEINAS; APOPROTEINE; APOPROTEINS; Avena - genetics; AVENA SATIVA; Base Sequence; Biological and medical sciences; CHEMICAL COMPOSITION; Chromophores; Codons; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; CRECIMIENTO; CROISSANCE; Development and Growth Regulation; DNA Mutational Analysis; Dose-Response Relationship, Radiation; ETAPAS DE DESARROLLO DE LA PLANTA; EXPRESION GENICA; EXPRESSION DES GENES; FAR RED LIGHT; FITOCROMA; Fluence; FOTORECEPTORES; Fundamental and applied biological sciences. Psychology; GENE EXPRESSION; GENE TRANSFER; GENETIC REGULATION; GENETIC VARIATION; GENETICA; GENETICS; GENETIQUE; GROWTH; Hypocotyl - radiation effects; Hypocotyls; INTERACTIONS; LIGHT; LIGHT HARVESTING COMPLEXES; LUMIERE; LUZ; Mature plants; Metabolism; MOLECULAR SEQUENCE DATA; Mutagenesis, Site-Directed; Nicotiana - genetics; Nicotiana - radiation effects; NICOTIANA TABACUM; Oats; Phenotype; PHOTORECEPTEUR; PHOTORECEPTORS; PHYTOCHROME; Phytochrome - chemistry; Phytochrome - genetics; Phytochrome - metabolism; Phytochrome A; PLANT DEVELOPMENTAL STAGES; Plant physiology and development; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants; Plants, Genetically Modified - radiation effects; Plants, Toxic; PLANTULAS; PLANTULE; Protein Conformation; PROTEINAS; PROTEINE; PROTEINS; RED LIGHT; SEEDLINGS; Sequence Deletion; SERINA; SERINE; Signal Transduction; Spectrophotometry; STADE DE DEVELOPPEMENT VEGETAL; Storage and secretion, pigments, phytochrome; TRANSFERENCIA DE GENES; TRANSFERT DE GENE; TRANSGENIC PLANTS; VARIACION GENETICA; VARIATION GENETIQUE; Avena sativa; Monocotyledones; Interaction; Site directed mutagenesis; Photoreceptor; Red light; Nicotiana tabacum; Structure function relationship; Biological activity; Regulation(control); Gramineae; Apoproteins; Dicotyledones; Angiospermae; Phytochrome; N terminal-Sequence; Deletion; Regulatory sequence; Spermatophyta; Transgenic plant; Solanaceae; Chromophore
• DOI: 10.1104/pp.115.2.693
• ISSN: 0032-0889

Phytochrome A (phyA) is a red/far-red (FR) light photoreceptor responsible for initiating numerous light-mediated plant growth and developmental responses, especially in FR light-enriched environments. We previously showed that the first 70 amino acids of the polypeptide contain at least two regions with potentially opposite functions (E.T. Jordan, J.R. Cherry, J.M. Walker, R.D. Vierstra [1996] Plant J 9:243-257). One region is required for activity and correct apoprotein/chromophore interactions, whereas the second appears to regulate phytochrome activity. We have further resolved these functional regions by analysis of N-terminal deletion and alanine-scanning mutants of oat (Avena sativa) phyA in transgenic tobacco (Nicotiana tabacum). The results indicate that the region involved in chromophore/apoprotein interactions contains two separate segments (residues 25-33 and 50-62) also required for biological activity. The region that regulates phyA activity requires only five adjacent serines (Sers) (residues 8-12). Removal or alteration of these Sers generates a photoreceptor that increases the sensitivity of transgenic seedlings to red and FR light more than intact phyA. Taken together, these data identify three distinct regions in the N-terminal domain necessary for photoreceptor activity, and further define the Ser-rich region as an important site for phyA regulation