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Local Pheromone Release from Dynamic Polarity Sites Underlies Cell-Cell Pairing
during Yeast Mating
#MMPMID27020743
Merlini L
; Khalili B
; Bendezú FO
; Hurwitz D
; Vincenzetti V
; Vavylonis D
; Martin SG
Curr Biol
2016[Apr]; 26
(8
): 1117-25
PMID27020743
show ga
Cell pairing is central for many processes, including immune defense, neuronal
connection, hyphal fusion, and sexual reproduction. How does a cell orient toward
a partner, especially when faced with multiple choices? Fission yeast
Schizosaccharomyces pombe P and M cells, which respectively express P and M
factor pheromones [1, 2], pair during the mating process induced by nitrogen
starvation. Engagement of pheromone receptors Map3 and Mam2 [3, 4] with their
cognate pheromone ligands leads to activation of the G? protein Gpa1 to signal
sexual differentiation [3, 5, 6]. Prior to cell pairing, the Cdc42 GTPase, a
central regulator of cell polarization, forms dynamic zones of activity at the
cell periphery at distinct locations over time [7]. Here we show that Cdc42-GTP
polarization sites contain the M factor transporter Mam1, the general secretion
machinery, which underlies P factor secretion, and Gpa1, suggesting that these
are sub-cellular zones of pheromone secretion and signaling. Zone lifetimes scale
with pheromone concentration. Computational simulations of pair formation through
a fluctuating zone show that the combination of local pheromone release and
sensing, short pheromone decay length, and pheromone-dependent zone stabilization
leads to efficient pair formation. Consistently, pairing efficiency is reduced in
the absence of the P factor protease. Similarly, zone stabilization at reduced
pheromone levels, which occurs in the absence of the predicted GTPase-activating
protein for Ras, leads to reduction in pairing efficiency. We propose that
efficient cell pairing relies on fluctuating local signal emission and
perception, which become locked into place through stimulation.
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