Does myosin xi interact with phospholipids and if so is this interaction important for tip growth in the moss Physcomitrella?

Physcomitrella patens is a type of moss which has recently sparked interest in plant studies because of the moss’ unique ability for several genetic manipulations, not possible in other plants. Nonetheless, because Physcomitrella patens have only recently been introduced as a prominent source of genetic manipulation, much is still not known about the moss; in particular to what is behind the movement of the tips of the cells. Tip-growth in plant cells is known to be the cell’s reaction to active secretion and polarization of several cellular components. It has been suggested that the primary source of this tip-growth is the transport of secretory vesicles through the molecular motor myosin-XI. It has also been suggested that in vivo this myosin can interact with phospholipids which could potentially indicate that these phospholipids could have a primary function in tip-growth. The interaction site in Physcomitrella patens is a positively charged area of the myosin molecule. We plan to take this positively charged region of the myosin molecule and interchange the argininines for alanines (AAA mutant). In making the AAA mutant we will then use RNAi complementation assay to stress the capacity of the mutant’s ability to complement the loss-function phenotype. If the AAA mutant fails to complement the loss-of-function phenotype, then this is a good indication that phospholipids are a definite functional source of interaction in the conserved region. This research will lead to a better understanding of tip growth, and potentially show us what this species of moss is capable of.