Molecular cloning and characterization of profilin from tobacco (Nicotiana tabacum): increased profilin expression during pollen maturation

Abstract

Profilin has recently been identified as an actin-binding protein in higher plants. A cDNA coding for tobacco profilin, which shared an average sequence identity of 75% with other plant profilins, was isolated from a tobacco pollen cDNA library by antibody screening. Tobacco profilin was expressed in Escherichia coli and purified by affinity to poly-(L-proline) Sepharose. A rabbit antiserum was raised against recombinant tobacco profilin and used to estimate the amount of profilin expressed in different tobacco tissues. Profilin can be detected in different somatic tissues, but the expression is 50-100 fold higher in mature pollen. Immunofluorescence and confocal laser scanning microscopy showed a homogeneous distribution of profilin in the cytoplasm of in vitro cultured pollen grains and pollen tubes of tobacco whereas some growing pollen tubes were stained more intensively a their tip. A possible role of pollen profilin as a developmentally upregulated microfilament precursor in mature pollen is discussed.

Profilin Is Essential for Tip Growth in the MossPhyscomitrella patens

“…In general, plants contain many profilin isoforms; for example, Arabidopsis has five Kandasamy et al, 2002), maize (Zea mays) has at least five (Staiger et al, 1993;Gibbon et al, 1998;Kovar et al, 2001a), and tobacco (Nicotiana tabacum) has at least three (Mittermann et al, 1995). To identify how many profilin genes are present in P. patens, we searched the P. patens genome (http://genome.jgi-psf.org//Phypa1_1/ Phypa1_1.home.html) and found three profilin genes.…”

Cytoskeleton-Associated Large RNP Complexes in Tobacco Male Gametophyte (EPPs) Are Associated with Ribosomes and Are Involved in Protein Synthesis, Processing, and Localization

“…33 To examine whether they also contained other transcripts, RT-PCR analysis was performed. Several tobacco pollen-specific genes were tested including profilin, 39 actin depolymerizing factor 1 (ADF1), 40 eukaryotic translation initiation factors eIF4E, eIFiso4E 41 and R-tubulin A1 (accession number AJ421411; D. Brevario, direct submission). RT-PCR analysis revealed that all tested transcripts were present in the EPP fractions isolated by ultracentrifugation as well as directly from SEC ( Figure 3).…”

Signaling and the Modulation of Pollen Tube Growth

“…Furthermore, several actin binding protein families, for example, actin depolymerizing factors and profilin, have been identified and cloned in pollen tubes (Staiger et al, 1993;Mitterman et al, 1995;Lopez et al, 1996;Vidali and Hepler, 1997;Yu et al, 1998). Although it is thought that pollen profilins play an important role in pollen tube growth by regulating microfilament formation, a thorough understanding of the regulation of actin dynamics and the exact role of the cytoskeleton in pollen tube growth is currently lacking.…”