Biochemical and physiological properties of a protein inducing protoplast release during conjugation in theClosterium peracerosum-strigosum-littorale complex

Abstract

When mating-type minus (mt(-)) and plus (mt(+)) cells of theClosterium peracerosum-strigosum-littorale complex were mixed together in a nitrogen-deficient mating medium, cells of both types released protoplasts, this release being the first step in the process of conjugation. Release of protoplasts by mt(-) cells also proceeded without pairing in a medium in which mt(-) and mt(+) cells had previously been cultured together. A protein with the ability to induce the release of protoplasts was purified from this medium by sequential column-chromatographic steps, and named PR-IP (protoplast-release-inducing protein). The PR-IP had an apparent molecular mass (Mr) of 95000 on gel filtration and could be separated into several isoforms by anion-exchange chromatography. Each isoform consisted of two glycopolypeptides of Mrs 42000 and 19000, while the deglycosylated polypeptides had Mrs of 34000 and 18000, respectively. From an analysis of dose-response curves, the numbers of PR-IP molecules required for the release of a protoplast by a single cell was calculated as 1.5·10(9) and the concentration required for 50% of the maximum response (ED50) as 4.1·10(-9)M. We suggest that the PR-IP is a biologically active glycoprotein which induces the release of gametic protoplasts from mt(-) cells of thisClosterium complex.

Gene Expression Profiling Using cDNA Microarray Analysis of the Sexual Reproduction Stage of the Unicellular Charophycean Alga Closterium peracerosum-strigosum-littorale Complex

“…The respective vegetative cells (mt 1 -V and mt 2 -V) were obtained from cultures grown in nitrogen-supplemented medium (C medium; http://www.nies.go.jp/biology/ mcc/home.htm), as described previously (Sekimoto et al, 1990). The sexual reproduction of C. pslc was induced as follows.…”

“…The deduced amino acid sequences of CpAQP1 and CpAQP2 showed 93.1% identity with each other and contained Asn-Pro-Ala motifs, which were conserved within the family. During sexual reproduction, condensation of the cytoplasm and release of protoplasts from the cell wall are observed (Sekimoto et al, 1990). For these processes, the content of water and/or some solutes in cells must undergo change.…”

Sexual Reproduction of a Unicellular Charophycean Alga, Closterium peracerosum-strogosum-littorale Complex

“…28.1 ). Sekimoto et al ( 1990 ) successfully isolated the fi rst Closterium pheromone from the C. psl. complex and designated it as protoplast-release-inducing protein (PR-IP) (Sekimoto et al 1990 ).…”

“…Sekimoto et al ( 1990 ) successfully isolated the fi rst Closterium pheromone from the C. psl. complex and designated it as protoplast-release-inducing protein (PR-IP) (Sekimoto et al 1990 ). The PR-IP is a glycoprotein that consists of subunits of 42 and 19 kDa: it is released by mt + cells (NIES-67) and is responsible for inducing the release of protoplasts from mt − cells (NIES-68) ( Fig.…”

Effect of antibiotics on cell proliferation in the Closterium peracerosum-strigosum-littorale complex (Charophyceae, Chlorophyta)

“…complex) belongs to unicellular charophycean green algae that have been used to elucidate aspects of sexual reproduction processes in plants, especially for the sexual differentiation and matingrelated cell-cell interaction (Sekimoto et al 2000). It has been well understood that these organisms secrete two sex pheromones, a protoplast-release-inducing protein (PR-IP) and a PR-IP Inducer which are critically involved in the progress of sexual reproductive processes under nutritional starved conditions (Sekimoto et al 1990;Nojiri et al 1995;Tsuchikane et al 2005;Akatsuka et al 2006). Recently, tools for studying the transcriptional basis of these organisms such as expressed sequence tag (EST) and microarray during reproductive processes have been established (Sekimoto et al 2003.…”