Identification and characterization of a matrix metalloproteinase (Pta1-MMP) expressed during Loblolly pine (Pinus taeda) seed development, germination completion, and early seedling establishment

Abstract

Extracellular matrix (ECM) modifications occur during plant growth, development, and in response to environmental stimuli. Key modulators of ECM modification in vertebrates, the extracellular matrix metalloproteinases (MMPs), have also been described in a few plants. Here, we report the identification of Loblolly pine (Pinus taeda) Pta1-MMP and its characterization during seed development and germination. Pta1-MMP protein has the structural characteristics of other plant MMPs, the recombinant protein exhibits Zn(2+)-dependent protease activity, and is inhibited by EDTA and the active site-binding hydroxamate inhibitor GM6001. The Pta1-MMP gene is expressed in both embryo and megagametophyte, with transcript levels increasing in both during the period from proembryo to early cotyledonary stage, then declining during late embryogenesis and maturation drying. Protein extracts exhibited similar developmental-stage MMP-like activity. Seed germination was stimulated by GA(3) and inhibited by ABA, and the timing of germination completion was mirrored by the presence of MMP-like protease activity in both water- and GA(3)-imbibed embryos. Pta1-MMP gene transcript levels increased in association with radicle protrusion for both GA(3)- and water-treated embryos, in agreement with MMP-like activity. In contrast, by 11 days after imbibition, Pta1-MMP gene transcripts in ABA-treated embryos were at levels similar to the other treatments, although MMP-like activity was not observed. The application of GM6001 during Loblolly pine seed germination inhibited radicle protrusion. Our results suggest that MMP activity may be involved in ECM modification, facilitating the cell division and expansion required during seed development, germination completion, and subsequent seedling establishment.

Biochemical properties of the matrix metalloproteinase NtMMP1 from Nicotiana tabacum cv. BY-2 suspension cells

“…ion in the active site (Maidment et al 1999). In contrast, the processing of recombinant Pta1-MMP occurs spontaneously without the addition of APMA Ratnaparkhe et al 2009). APMA does also not affect the processing of NtMMP1 (Schiermeyer et al 2009) suggesting that NtMMP1 does not use the cysteine switch mechanism despite having the corresponding motif.…”

“…MMPs are structurally diverse, but most require zinc ions for their activity, others relying on cobalt or nickel ions. MMPs have been isolated from a variety of plant species, including the angiosperms Arabidopsis thaliana (Maidment et al 1999), Glycine max (Pak et al 1997;Liu et al 2001), Cucumis sativus (Delorme et al 2000), Medicago truncatula (Combier et al 2007) and Nicotiana tabacum (Schiermeyer et al 2009) and the gymnosperm Pinus taeda (Ratnaparkhe et al 2009). They are thought to play roles in plant development (Graham et al 1991), senescence (Delorme et al 2000) and defense (Pak et al 1997;Schiermeyer et al 2009), although their precise functions and natural substrates remain unknown.…”

Cell death control by matrix metalloproteinases in tomato

“…Plant MMPs have been described in several species, including soybean (Glycine max; Graham et al, 1991;McGeehan et al, 1992;Pak et al, 1997;Liu et al, 2001), cucumber (Cucumis sativus; Delorme et al, 2000), pine (Pinus spp. ; Ratnaparkhe et al, 2009), Nicotiana benthamiana (Schiermeyer et al, 2009;Mandal et al, 2010), tomato (Solanum lycopersicum; Li et al, 2015), and Arabidopsis (Arabidopsis thaliana; Maidment et al, 1999;Golldack et al, 2002). Some of these enzymes have been characterized with respect to activity and specificity for small peptide substrates in vitro, but their physiological substrates and functions in vivo remain elusive (Flinn, 2008;Marino and Funk, 2012;Marino et al, 2014).…”

“…Some of these enzymes have been characterized with respect to activity and specificity for small peptide substrates in vitro, but their physiological substrates and functions in vivo remain elusive (Flinn, 2008;Marino and Funk, 2012;Marino et al, 2014). Largely based on expression patterns, plant MMPs have been implicated in a variety of physiological processes, including seed development and germination (Ratnaparkhe et al, 2009), programmed cell death (Delorme et al, 2000), and pathogen defense Frick and Schaller, 2002;Schiermeyer et al, 2009). In a few studies, the role of plant MMPs was addressed more directly by loss-of-function analysis.…”

NMMP1, a Matrix Metalloprotease in Nicotiana benthamiana Has a Role in Protection against Bacterial Infection

“…Several matrixins have been isolated from plants, including soybean (Graham et al, 1991;Liu et al, 2001;McGeehan et al, 1992;Pak et al, 1997), Arabidopsis (Maidment et al, 1999;Golldack et al, 2002), cucumber (Delorme et al, 2000), alfalfa (Combier et al, 2007), Pinus taeda (Ratnaparkhe et al, 2009), and Nicotiana tabacum (Schiermeyer, 2009). Matrixins have zinc at their catalytic center and are sensitive to EDTA (McGeehan et al, 1992).…”