Multiple Actin Isotypes in Plants: Diverse Genes for Diverse Roles?

Kateřina Šlajcherová,Kateřina Schwarzerová,Jindřiška Fišerová,Lukáš Fischer

doi:10.3389/fpls.2012.00226

Abstract

Plant actins are encoded by a gene family. Despite the crucial significance of the actin cytoskeleton for plant structure and function, the importance of individual actin isotypes and their specific roles in various plant tissues or even single cells is rather poorly understood. This review summarizes our current knowledge about the plant actin gene family including its evolution, gene and protein structure, and the expression profiles and regulation. Based on this background information, we review mutant and complementation analyses in Arabidopsis to draw an emerging picture of overlapping and specific roles of plant actin isotypes. Finally, we examine hypotheses explaining the mechanisms of isotype-specific functions.

Highlights

Actin is an essential protein that is expressed throughout the plant body in many distinct isotypes
To better understand the existence and role of multiple actin isotypes in plants, this review first summarizes what is known about the structure of actin genes, evolution of the gene family, and expression regulation
The function of the 5 UTR as a regulatory element was described for ACT7 (Gilliland et al, 2003) and ACT1 (Vitale et al, 2003), suggesting that the leader intron plays a crucial role in actin expression and that this regulation may be common to all actin isotypes

Summary

INTRODUCTION

Actin is an essential protein that is expressed throughout the plant body in many distinct isotypes (the term isotype is commonly used for closely related proteins, and isoform or isovariant are often used as synonyms to isotype). To better understand the existence and role of multiple actin isotypes in plants, this review first summarizes what is known about the structure of actin genes, evolution of the gene family, and expression regulation. MULTIPLE ACTIN GENES AND THEIR STRUCTURE The numbers of actin genes in various plant species examined so far indicate that this gene family is quite variable. The total number of actin family members present in public databases (National Center for Biotechnology Information, NCBI1, Plant Genome Database, and Phytozome; Table 1) partially reflects the complexity of the respective organism. The plant actin gene family seems to be rather more diversified and complex compared with other multicellular organisms. Other factors are likely to contribute to the evolution of the complex actin gene family in plants. The family contains 10 actin genes (ACT ), eight of which encode functional proteins and www.frontiersin.org

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Possible roles

Callus formation

Findings

CONCLUSION