The lurlenes, a new class of plastoquinone-related mating pheromones from Chlamydomonas allensworthii (Chlorophyceae)

Chlamydomonas allensworthii is a recently described species, which differs phenotypically and in its reproductive behaviour from other members of this genus of flagellated green protists. Its female cells temporarily or constantly excrete a luring signal into the medium to attract the male cells for mating. The sperm is susceptible to the pheromone either all the time or only after a maturation process. Maturation in this species is accompanied with a colour shift from green to khaki (strain from Lemon cove CA) or to olive (strain from Catarina TX), apparently due to degradation of chloroplast material. In the bioassay with polyacrylamide beads (plain or DEAE-substituted) to which the lures are bound, acting as mock females, Catarina-strain males are only attracted to Catarina strain lures, whereas Lemon-Cove-strain males are attracted to Lemon-Cove-strain lures and to a lesser extent, to Catarina-strain lures. Being amphiphilic acid, Lemon-Cove-strain lure is more tightly bound to DEAE beads. Catarina-strain lure is an uncharged amphiphile. The two signal compounds have been isolated and identified by chemical analysis and mass and NMR spectroscopies as O(5)-beta-D-xylosylated degradation products of the chloroplast electron transporter hydroplastoquinone, its polyprenoid side chain being oxidatively cleaved at the fourth double bond. Lurlenic acid (lurlene L) is the resulting acid and lurlenol (lurlene C) the corresponding alcohol. The pheromonal activities of both compounds have a threshold at 1 pM, and are destroyed by deglycosylation and subsequent oxidation to the quinonoid aglycon. This class of amphiphilic lures, having the same basic glycosylated hydroquinone structure, is named lurlenes.