Regulation of the pollen-specific actin-depolymerizing factor LlADF1.
Pollen tube growth is dependent on a dynamic actin cytoskeleton, suggesting that actin-regulating proteins are involved. We have examined the regulation of the lily pollen-specific actin-depolymerizing factor (ADF) LlADF1. Its actin binding and depolymerizing activity is pH sensitive, inhibited by certain phosphoinositides, but not controlled by phosphorylation. Compared with its F-actin binding properties, its low activity in depolymerization assays has been used to explain why pollen ADF decorates F-actin in pollen grains. This low activity is incompatible with a role in increasing actin dynamics necessary to promote pollen tube growth. We have identified a plant homolog of actin-interacting protein, AIP1, which enhances the depolymerization of F-actin in the presence of LlADF1 by approximately 60%. Both pollen ADF and pollen AIP1 bind F-actin in pollen grains but are mainly cytoplasmic in pollen tubes. Our results suggest that together these proteins remodel actin filaments as pollen grains enter and exit dormancy.
Allwood
Ellen G
EG
Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
Anthony
Richard G
RG
Smertenko
Andrei P
AP
Reichelt
Stefanie
S
Drobak
Bjorn K
BK
Doonan
John H
JH
Weeds
Alan G
AG
Hussey
Patrick J
PJ
D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D029688:Brassica napus / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D003599:Cytoskeleton / Q000378:metabolism; D051345:Destrin; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D027762:Lilium / Q000235:genetics / Q000378:metabolism; D019684:Magnoliopsida / Q000235:genetics* / Q000378:metabolism; D008840:Microfilament Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D010743:Phospholipids / Q000494:pharmacology; D010766:Phosphorylation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011058:Pollen / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D003313:Zea mays / Q000235:genetics / Q000378:metabolism
C408685:AIP1 protein, Arabidopsis; D051339:Actin Depolymerizing Factors; D000199:Actins; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D051345:Destrin; D008840:Microfilament Proteins; D010743:Phospholipids; D010940:Plant Proteins; C115237:actin interacting protein 1