Plant ADF

Plant ADF/Cofilins

Page updated 12/11/02

Historically, members of the ADF/Cofilin protein family from plants have been described as ADFs (Actin Depolymerizing Factors) rather than cofilins, since the first plant member identified from cDNA (Lilium and Brassica), bore a more immediately recognisable sequence to animal ADFs (Kim et al, 1993). These cDNAs encoding putative plant ADFs were determined to be genuine actin-binding proteins some three years later (Lopez et al, 1996). They were characterized as having the usual actin-binding properties of their animal homologs but some are less able to sever actin filaments and are thus associated with F-actin structures within the living plant cell (Allwood et al, 2002). Like animal ADF/cofilins, they are pH dependent (Gungabissoon et al, 2001; Allwood et al, 2002) tending to bind F-actin at low pH and actin monomer at higher values. Single plant species tend to express multiple ADF genes Arabidopsis for example has ten genes

Name	Function	References
AIP1	An actin-binding protein that synergises with ADF/cofilins to increase depolymerising activity	Allwood et al, 2002
CAPS	An adenylate cyclase associated protein that also interacts with ADF/cofilins	Barrero et al, 2002
CDPK	Calmodulin-like domain protein kinase. There are many CDPKs in plant tissues and they perform a variety of different functions. The type of CDPK that regulates ADF has yet to be identified.	Allwood et al, 2001; Smertenko et al, 1998

Figure 1 ADF interacting plant proteins

Intriguingly not only do AIP1 and CAP1 interact with ADF, but they have been shown (yeast 2 hybrid) to interact with each other (Drees et al, 2001). Animal cells express LIM and TES kinases whose only known substrates are animal ADF/cofilins, however, it seems that there are no homologs in the now complete Arabidopsis genome (Allwood et al, 2001), and mammalian LIM kinases do not phosphorylate plant ADFs (Bamburg, 1999). The residue that is phosphorylated is like other ADF/cofilins is close to the N-terminus (Serine 6 in many plant ADFs) (Smertenko et al, 1998). The N-terminus of plant ADFs is slightly extended compared to other ADF/cofilins (Figure 2).

MANAASGMAVHDDCKLRFLELKAKRTHRFIVYK    Arabidopsis thaliana     ADF1, AF102173 U48938
MANASSGVAVSDDCKLKFQELQRKKAFLFIVFK   Psychomitrella patens   ADF, BU051611
MANAASGMAVLDECKLKFLELKAKRNYRFIVFK    Nicotiana tabacum        Pollen specific ADF2, AY081942 (Chen et al, 2002).
        MASGVAVSDGVIKVFNDMKVRKSSTPEEVK Human non-muscle         Cofilin, 105664

Figure 2 N-terminus of various plant ADF compared to vertebrate cofilin phosphorylated serine in bold blue.

Sub-cellular localization
Animal ADF/cofilins are only very occasionally localised along F-actin containing structures (the exception being stress induced nuclear and cytoplasmic rods). In plant cells however, ADFs are often seen in association with actin filament bundles and other F-actin containing structures in normal stress free situations. ADF is localized to the growing root tip in maize, not F-actin bundles (Jiang et al, 1997a) and a similar pattern has been found in the growing pollen tube (), although other studies report ADF being concentrated with "sub-cellular" particles within the pollen tube (Chung et al, 1995).

References:-

Allwood, E. G., Smertenko, A. P. & Hussey, P. J. (2001) Phosphorylation of plant actin-depolymerising factor by calmodulin-like domain protein kinase. FEBS letters. 499, 97-100.

Allwood, E. G., Anthony, R. G., Smertenko, A. P., Reichelt, S., Drobak, B. K., Doonan, J. H., Weeds, A. G. & Hussey, P. J. (2002) Regulation of the pollen-specific actin-depolymerizing factor LiADF1. Plant Cell. 14, 2915-2927.

Bamburg, J. R. (1999) Proteins of the ADF/cofiln family: Essential regulators of actin dynamics. Ann.Rev.Cell Dev.Biol. 15, 185-230.

Barrero, R. A., Umeda, M., Yamamura, S. & Uchimiya, H. (2002) Arabidopsis CAP regulates the actin cytoskeleton necessary for plant cell elongation and division. The Plant Cell. 14, 149-163.

Bowman, G. D., Nodelman, I. M., Hong, Y., Chua, N.-H., Linberg, U. & Schutt, C. E. (2000) A comparative structural analysis of the ADF/Cofilin family. Proteins. 41, 374-384.

Chen, C. Y., Wong, E. I., Vidali, L., Estavillo, A., Hepler, P. K., Wu, H.-m. & Cheung, A. Y. (2002) The Regulation of Actin Organization by Actin-Depolymerizing Factor in Elongating Pollen Tubes. Plant Cell. 14, 2175-2190.

Chung, Y. Y., Magnuson, N. S. & An, G. H. (1995) Subcellular-localization of actin depolymerizing factor in mature and germinating pollen. Molecules And Cells. 5, 224-229.

Dong, C.-H., Kost, B., Xia, G. & Chua, N.-H. (2001) Molecular identification and characterization of the Arabidopsis AtADF1, AtADF5 and AtADF6 genes. Plant Mol. Biol. 45, 517-527.

Dong, C.-H., Xia, G.-X., Hong, Y., Ramachandran, S., Kost, B. & Chua, N. H. (2001) ADF proteins are involved in the control of flowering and regulate F-actin organization, cell expansions, and organ growth in Arabidopsis. Plant Cell. 13, 1333-1346.

Drees, B.L. et al. (2001) A protein interaction map for cell polarity development. J.Cell Biol. 154, 549-571.

Galkin, V. E., Orlova, A., Lukoyanova, N., Wriggers, W. & Egelman, E. H. (2001) Actin depolymerization factor stabilizes an existing state of F-actin and can change the tilt of F-actin subunits. J.Cell Biol. 153, 75-86.

Gungabissoon, R. A., Khan, S., Hussey, P. J. & Maciver, S. K. (2001) Interaction of EF1a from Zea mays (ZmEF1a) with F-actin and interplay with the maize actin severing protein, ZmADF3. Cell Motility Cytoskeleton. 49, 104-111.

Hepler, P. K., Vidali, L. & Cheung, A. Y. (2001) Polarized cell growth in higher plants. Annu.Rev.Cell Dev.Biol. 17, 159-187.

Jiang, C.-J., A.G., W. & Hussey, P. J. (1997a) The maize actin-depolymerizing factor, ZmADF3, redistributes to the growing tip of elongating root hairs and can be induced to translocate into the nucleus with actin., Plant J. 12, 1035-1043.

Jiang, C.-J., Weeds, A. G., Khan, S. & Hussey, P. J. (1997b) F-actin and G-actin binding are uncoupled by mutation of conserved tyrosine residues in maize actin depolymerizing factor (ZmADF). Proc.Nat.Acad.Sci.USA. 94.

Kim, S.-R., Kim, Y. & An, G. (1993) Molecular cloning and characterization of anther-preferential cDNA encoding a putative actin-depolymerizing factor. Plant Mol. Biol. 21, 39-45.

Lopez, I., Anthony, R. G., Maciver, S. K., Jiang, C.-J., Khan, S., Weeds, A. G. & Hussey, P. J. (1996) Pollen specific expression of maize genes encoding actin depolymerizing factor-like proteins. Proc. Natl. Acad. Sci. 93, 7415-7420.

Maciver, S. K. & Hussey, P. J. (2002) The ADF/cofilin family: Actin-remodeling proteins. Genome Biology. 3, 3007.1-3007.12.

McCurdy, D. W., Kovar, D. R. & Staiger, C. J. (2001) Actin and actin-binding proteins in higher plants. Protoplasma. 215, 89-104.

Mun, J.-H., Yu, H.-J., Lee, H. S., Kwon, Y. M., Lee, J. S., Lee, I. & Kim, S.-G. (2000) Two closely related cDNA encoding actin-depolymerizing factors of Petunia are mainly expressed in vegetative tissues. Gene. 257, 167-176.

Ouellet, F., Carpentier, E., Cope, M. J. T. V., Monroy, A. F. & Sarhan, F. (2001) Regulation of a wheat Actin-Depolymerizing Factor during cold acclimation. Plant Physiol. 125.

Ressad, F., Didry, D., Xia, G.-X., Hong, Y., Chua, N.-H., Pantaloni, D. & Carlier, M. F. (1998) Kinetic analysis of the interaction of actin-depolymerizing factor (ADF)/cofilin with G- and F-actins. J.Biol.Chem. 273, 20894-20902.

Smertenko, A. P., Allwood, E. G., Khan, S., Jiang, C.-J., Maciver, S. K., Weeds, A. G. & Hussey, P. J. (2001) Interaction of pollen-specific actin-depolymerizing factor with actin. Plant J. 25, 1-11.

Smertenko, A. P., Jiang, C.-J., Simmons, N. J., Weeds, A. G., Davies, D. R. & Hussey, P. J. (1998) Ser6 in the maize actin-depolymerizing factor, ZmADF3, is phosphorylated by a calcium-stimulated protein kinase and is essential for the control of functional activity. Plant J. 14, 187-193.

Volkmann, D. & Baluska, F. (1999) Actin cytoskeleton in plants: from transport networks to signaling networks. Microsc.Res.Tech. 47, 135-154.