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Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells.

Woriedh M, Merkl R, Dresselhaus T - J. Exp. Bot. (2015)

Bottom Line: Furthermore, peptide fragments were found to bind differently to fungal cells.Mapping of peptide interaction sites identified amino acids differing in pollen tube burst and fungal response reactions.In summary, these findings indicate that residues targeting pollen tube burst in maize are specific to the ES family, while residues targeting fungal growth are conserved within defensins and defensin-like peptides.

View Article: PubMed Central - PubMed

Affiliation: Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany.

No MeSH data available.


Related in: MedlinePlus

Sequences, phylogram, and 3D model of ES1–4 peptides and derived peptide fragments used in this study. (A) Amino acid sequences of maize ES1, ES2, ES3, and ES4 are highly similar and have in common a conserved defensin/DEFL motif of eight cysteines forming four intramolecular disulfide bridges. A black arrowhead marks predicted cleavage sites. Asterisks indicate identical amino acids of ES1–4 and double colons indicate mismatches. ES proteins were divided into five highly conserved peptide fragments (ES-a to ES-e including mutated fragments named mES) used for functional studies and mapping of interaction domains. Amino acids of ES-c and ES-d affecting maize pollen tube burst (see below) are highlighted in blue and red, respectively. Amino acids of ES-c and ES-d affecting growth of fungi are indicated by blue and red asterisks, respectively. (B) Protein sequences of ES1–4 were aligned by means of MEGA6.06 (Tamura et al., 2013) and used to compute a maximum likelihood tree. The tree indicates the close relationship of ES2, ES3, and ES4 and the isolation of ES1. (C) Knottin structure of ES1–4 containing an antiparallel βαββ sheet and four disulfide bridges. (D) 3D structure of ES4 showing properties of individual surface residues. Colour code: grey, polar; blue, hydrophobic; orange, acidic; and purple, basic. The image was generated using PyMOL.
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Figure 1: Sequences, phylogram, and 3D model of ES1–4 peptides and derived peptide fragments used in this study. (A) Amino acid sequences of maize ES1, ES2, ES3, and ES4 are highly similar and have in common a conserved defensin/DEFL motif of eight cysteines forming four intramolecular disulfide bridges. A black arrowhead marks predicted cleavage sites. Asterisks indicate identical amino acids of ES1–4 and double colons indicate mismatches. ES proteins were divided into five highly conserved peptide fragments (ES-a to ES-e including mutated fragments named mES) used for functional studies and mapping of interaction domains. Amino acids of ES-c and ES-d affecting maize pollen tube burst (see below) are highlighted in blue and red, respectively. Amino acids of ES-c and ES-d affecting growth of fungi are indicated by blue and red asterisks, respectively. (B) Protein sequences of ES1–4 were aligned by means of MEGA6.06 (Tamura et al., 2013) and used to compute a maximum likelihood tree. The tree indicates the close relationship of ES2, ES3, and ES4 and the isolation of ES1. (C) Knottin structure of ES1–4 containing an antiparallel βαββ sheet and four disulfide bridges. (D) 3D structure of ES4 showing properties of individual surface residues. Colour code: grey, polar; blue, hydrophobic; orange, acidic; and purple, basic. The image was generated using PyMOL.

Mentions: The sequences of ES1–4 peptides are highly similar to each other (Cordts et al., 2001). ES4 shows a sequence identity of about 97% with ES2 and ES3, and of about 91% with ES1 (Fig. 1A, B). Three C-terminal mismatches distinguish mature peptides of ES1 and ES4 and another mismatch occurs in the hypervariable region ES-d (see below). Thus, predicted mature ES1 and ES4 peptides consisting of 61 amino acids were selected for functional studies. Mature ES family peptides were first divided into five highly conserved fragments named ES-a, ES-b, ES-c, ES-d, and ES-e (13–16 amino acids in length; Fig. 1A, B). These peptides and variants of ES-d were used for interaction and mapping studies. Moreover, considering that ES1-4 genes encode peptides with structural homology to defensins and DEFLs, PyMOL (version 1.7.4; The PyMOL Molecular Graphics System, Version 1.7.4 Schrödinger, LLC) was used to generate homology models based on known 3D structures deduced from the protein data bank (Bernstein et al., 1977). The 3D structure is characterized by a well-defined 3-stranded anti-parallel beta-sheet and a short alpha helix. Four disulfide bridges are located in the hydrophobic core between helix and sheet, forming a cysteine-stabilized alpha-helical motif (Fig. 1C). This structure is homologous to plant defensins and DEFLs, and analogous to scorpion toxins and insect defensins. However, an extended loop occurs in the ES-d peptide between Cys5 and Cys6. Therefore, the two variants mature ES-d1 (mES-d1) and mES-d2, as well as an altered mES4 peptide, were generated (Fig. 1A). For ES4, the electrostatic surface was calculated by means of PyMOL in order to visualize the distribution of charges and of hydrophobic and polar surfaces in an amino-acid-specific manner in 3D (Fig. 1D). The model shows that ES1–4 are hydrophobic peptides, contain a flexible C-terminus, and the domain containing ES-d is exposed from the surface of the molecule.


Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells.

Woriedh M, Merkl R, Dresselhaus T - J. Exp. Bot. (2015)

Sequences, phylogram, and 3D model of ES1–4 peptides and derived peptide fragments used in this study. (A) Amino acid sequences of maize ES1, ES2, ES3, and ES4 are highly similar and have in common a conserved defensin/DEFL motif of eight cysteines forming four intramolecular disulfide bridges. A black arrowhead marks predicted cleavage sites. Asterisks indicate identical amino acids of ES1–4 and double colons indicate mismatches. ES proteins were divided into five highly conserved peptide fragments (ES-a to ES-e including mutated fragments named mES) used for functional studies and mapping of interaction domains. Amino acids of ES-c and ES-d affecting maize pollen tube burst (see below) are highlighted in blue and red, respectively. Amino acids of ES-c and ES-d affecting growth of fungi are indicated by blue and red asterisks, respectively. (B) Protein sequences of ES1–4 were aligned by means of MEGA6.06 (Tamura et al., 2013) and used to compute a maximum likelihood tree. The tree indicates the close relationship of ES2, ES3, and ES4 and the isolation of ES1. (C) Knottin structure of ES1–4 containing an antiparallel βαββ sheet and four disulfide bridges. (D) 3D structure of ES4 showing properties of individual surface residues. Colour code: grey, polar; blue, hydrophobic; orange, acidic; and purple, basic. The image was generated using PyMOL.
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Related In: Results  -  Collection

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Figure 1: Sequences, phylogram, and 3D model of ES1–4 peptides and derived peptide fragments used in this study. (A) Amino acid sequences of maize ES1, ES2, ES3, and ES4 are highly similar and have in common a conserved defensin/DEFL motif of eight cysteines forming four intramolecular disulfide bridges. A black arrowhead marks predicted cleavage sites. Asterisks indicate identical amino acids of ES1–4 and double colons indicate mismatches. ES proteins were divided into five highly conserved peptide fragments (ES-a to ES-e including mutated fragments named mES) used for functional studies and mapping of interaction domains. Amino acids of ES-c and ES-d affecting maize pollen tube burst (see below) are highlighted in blue and red, respectively. Amino acids of ES-c and ES-d affecting growth of fungi are indicated by blue and red asterisks, respectively. (B) Protein sequences of ES1–4 were aligned by means of MEGA6.06 (Tamura et al., 2013) and used to compute a maximum likelihood tree. The tree indicates the close relationship of ES2, ES3, and ES4 and the isolation of ES1. (C) Knottin structure of ES1–4 containing an antiparallel βαββ sheet and four disulfide bridges. (D) 3D structure of ES4 showing properties of individual surface residues. Colour code: grey, polar; blue, hydrophobic; orange, acidic; and purple, basic. The image was generated using PyMOL.
Mentions: The sequences of ES1–4 peptides are highly similar to each other (Cordts et al., 2001). ES4 shows a sequence identity of about 97% with ES2 and ES3, and of about 91% with ES1 (Fig. 1A, B). Three C-terminal mismatches distinguish mature peptides of ES1 and ES4 and another mismatch occurs in the hypervariable region ES-d (see below). Thus, predicted mature ES1 and ES4 peptides consisting of 61 amino acids were selected for functional studies. Mature ES family peptides were first divided into five highly conserved fragments named ES-a, ES-b, ES-c, ES-d, and ES-e (13–16 amino acids in length; Fig. 1A, B). These peptides and variants of ES-d were used for interaction and mapping studies. Moreover, considering that ES1-4 genes encode peptides with structural homology to defensins and DEFLs, PyMOL (version 1.7.4; The PyMOL Molecular Graphics System, Version 1.7.4 Schrödinger, LLC) was used to generate homology models based on known 3D structures deduced from the protein data bank (Bernstein et al., 1977). The 3D structure is characterized by a well-defined 3-stranded anti-parallel beta-sheet and a short alpha helix. Four disulfide bridges are located in the hydrophobic core between helix and sheet, forming a cysteine-stabilized alpha-helical motif (Fig. 1C). This structure is homologous to plant defensins and DEFLs, and analogous to scorpion toxins and insect defensins. However, an extended loop occurs in the ES-d peptide between Cys5 and Cys6. Therefore, the two variants mature ES-d1 (mES-d1) and mES-d2, as well as an altered mES4 peptide, were generated (Fig. 1A). For ES4, the electrostatic surface was calculated by means of PyMOL in order to visualize the distribution of charges and of hydrophobic and polar surfaces in an amino-acid-specific manner in 3D (Fig. 1D). The model shows that ES1–4 are hydrophobic peptides, contain a flexible C-terminus, and the domain containing ES-d is exposed from the surface of the molecule.

Bottom Line: Furthermore, peptide fragments were found to bind differently to fungal cells.Mapping of peptide interaction sites identified amino acids differing in pollen tube burst and fungal response reactions.In summary, these findings indicate that residues targeting pollen tube burst in maize are specific to the ES family, while residues targeting fungal growth are conserved within defensins and defensin-like peptides.

View Article: PubMed Central - PubMed

Affiliation: Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany.

No MeSH data available.


Related in: MedlinePlus