Faculty of Natural Sciences

TY - JOUR

T1 - Structure-function analysis of the GmRIC1 signal peptide and CLE domain required for nodulation control in soybean

AU - Reid, Dugald

AU - Li, Dongxue

AU - Ferguson, Brett J

AU - Gresshoff, Peter M

PY - 2013/4

Y1 - 2013/4

N2 - Legumes control the nitrogen-fixing root nodule symbiosis in response to external and internal stimuli, such as nitrate, and via systemic autoregulation of nodulation (AON). Overexpression of the CLV3/ESR-related (CLE) pre-propeptide-encoding genes GmNIC1 (nitrate-induced and acting locally) and GmRIC1 (Bradyrhizobium-induced and acting systemically) suppresses soybean nodulation dependent on the activity of the nodulation autoregulation receptor kinase (GmNARK). This nodule inhibition response was used to assess the relative importance of key structural components within and around the CLE domain sequences of these genes. Using a site-directed mutagenesis approach, mutants were produced at each amino acid within the CLE domain (RLAPEGPDPHHN) of GmRIC1. This approach identified the Arg1, Ala3, Pro4, Gly6, Pro7, Asp8, His11, and Asn12 residues as critical to GmRIC1 nodulation suppression activity (NSA). In contrast, none of the mutations in conserved residues outside of the CLE domain showed compromised NSA. Chimeric genes derived from combinations of GmRIC1 and GmNIC1 domains were used to determine the role of each pre-propeptide domain in NSA differences that exist between the two peptides. It was found that the transit peptide and CLE peptide regions of GmRIC1 significantly enhanced activity of GmNIC1. In contrast, the comparable GmNIC1 domains reduced the NSA of GmRIC1. Identification of these critical residues and domains provides a better understanding of how these hormone-like peptides function in plant development and regulation.

AB - Legumes control the nitrogen-fixing root nodule symbiosis in response to external and internal stimuli, such as nitrate, and via systemic autoregulation of nodulation (AON). Overexpression of the CLV3/ESR-related (CLE) pre-propeptide-encoding genes GmNIC1 (nitrate-induced and acting locally) and GmRIC1 (Bradyrhizobium-induced and acting systemically) suppresses soybean nodulation dependent on the activity of the nodulation autoregulation receptor kinase (GmNARK). This nodule inhibition response was used to assess the relative importance of key structural components within and around the CLE domain sequences of these genes. Using a site-directed mutagenesis approach, mutants were produced at each amino acid within the CLE domain (RLAPEGPDPHHN) of GmRIC1. This approach identified the Arg1, Ala3, Pro4, Gly6, Pro7, Asp8, His11, and Asn12 residues as critical to GmRIC1 nodulation suppression activity (NSA). In contrast, none of the mutations in conserved residues outside of the CLE domain showed compromised NSA. Chimeric genes derived from combinations of GmRIC1 and GmNIC1 domains were used to determine the role of each pre-propeptide domain in NSA differences that exist between the two peptides. It was found that the transit peptide and CLE peptide regions of GmRIC1 significantly enhanced activity of GmNIC1. In contrast, the comparable GmNIC1 domains reduced the NSA of GmRIC1. Identification of these critical residues and domains provides a better understanding of how these hormone-like peptides function in plant development and regulation.

KW - Amino Acid Motifs

KW - Amino Acid Sequence

KW - Bradyrhizobium

KW - Gene Expression Regulation, Plant

KW - Genes, Plant

KW - Molecular Sequence Data

KW - Mutagenesis, Site-Directed

KW - Nitrogen Fixation

KW - Plant Proteins

KW - Plant Root Nodulation

KW - Plants, Genetically Modified

KW - Point Mutation

KW - Protein Sorting Signals

KW - Soybeans

KW - Static Electricity

KW - Structure-Activity Relationship

KW - Symbiosis

U2 - 10.1093/jxb/ert008

DO - 10.1093/jxb/ert008

M3 - Journal article

C2 - 23386683

VL - 64

SP - 1575

EP - 1585

JO - Journal of Experimental Botany

JF - Journal of Experimental Botany

IS - 6

ER -