Diverse Roles of CCCH Zinc Finger Proteins in Stress and Plant Development Responses

Proteins containing zinc finger domains are highly abundant in eukaryotes. Of these, the CCCH class of motifs, where a zinc ion is postulated to be coordinated by three cysteine and one histidine residues, are present in a large number of proteins. Recent studies have implicated the members of this class in a wide variety of cellular functions ranging from developmental activities to amelioration of biotic and abiotic stresses. Animal CCCH zinc finger proteins recognize destabilizing AU-rich elements in the 3'-untranslated regions of messenger RNAs targeting them for degradation. Genetic analysis of plant proteins indicates their involvement in mRNA processing, floral morphogenesis, senescence, hormone-mediated environmental, biotic and abiotic stress responses. Furthermore, plant proteins exhibit differential expression patternsindicating diverse biological roles. Several plant proteins have similar functions and properties, such as trafficking between the nucleus and cytoplasm, and co-localizing with markers of processing bodies (PBs) or stress granules, although such proteins differ in zinc finger motif number they possess. Biochemical studies reveal that individual motifs of tandem fingers might participate in protein-protein interactions, nucleic acid binding, contributing ribonuclease activity or even calmodulin-mediated calcium signaling. This chapter summarizes the recent advances and current thinking of this protein family in plants including genome level characterization, classification, nucleic acid binding features, site directed mutagenesis based functional characterization, and finally, the future directions to fill the gaps in structural information.And copy 2012 Nova Science Publishers, Inc.