Apical myosin XI anticipates F‐actin during polarized growth of Physcomitrella patens cells. (26th November 2012)

• Record Type: Journal Article
• Authors: Furt, Fabienne; Liu, Yen‐Chun; Bibeau, Jeffrey P.; Tüzel, Erkan; Vidali, Luis
• Is Part Of: Plant journal. Volume 73:Number 3(2013:Feb.)
• Page Start: 417
• Page End: 428
• Publication Date: 2012-11-26
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12039
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12039-abs-0001"> <title>Summary</title> <p>Tip growth is essential for land colonization by bryophytes, plant sexual reproduction and water and nutrient uptake. Because this specialized form of polarized cell growth requires both a dynamic actin cytoskeleton and active secretion, it has been proposed that the F‐actin‐associated motor myosin XI is essential for this process. Nevertheless, a spatial and temporal relationship between myosin XI and F‐actin during tip growth is not known in any plant cell. Here, we use the highly polarized cells of the moss <italic>Physcomitrella patens</italic> to show that myosin XI and F‐actin localize, <italic>in vivo</italic>, at the same apical domain and that both signals fluctuate. Surprisingly, phase analysis shows that increase in myosin XI anticipates that of F‐actin; in contrast, myosin XI levels at the tip fluctuate in identical phase with a vesicle marker. Pharmacological analysis using a low concentration of the actin polymerization inhibitor latrunculin B showed that the F‐actin at the tip can be significantly diminished while myosin XI remains elevated in this region, suggesting that a mechanism exists to cluster myosin XI‐associated structures at the cell's apex. In addition, this approach uncovered a mechanism for actin polymerization‐dependent motility in the moss cytoplasm, where myosin XI‐associated structures seem to anticipate and organize the actin polymerization machinery. From our results, we inferred a model where the interaction between myosin XI‐associated vesicular structures and F‐actin polymerization‐driven motility function at the cell's apex to maintain polarized cell growth. We hypothesize this is a general mechanism for the participation of myosin XI and F‐actin in tip growing cells.</p> </abstract>