Putative Arabidopsis homologues of metazoan coiled‐coil cytoskeletal proteins

Abstract

The Arabidopsis thaliana genome encodes about 386 proteins with coiled-coil domains of at least 50 amino acids in length. In mammalian systems, many coiled-coil proteins are part of various cytoskeletal networks including intermediate filament protein, actin-binding proteins and MAP (microtubule-associated proteins). Immunological evidence suggests that some of these cytoskeletal proteins, such as lamins, keratins and tropomyosins, may be conserved in Arabidopsis. However, coiled-coil proteins are of low complexity, and thus, traditional sequence comparison algorithms, such as BLAST may not detect homologies. Here, we use the PROPSEARCH algorithm to detect putative coiled-coil cytoskeletal protein homologues in Arabidopsis. This approach reveals putative intermediate filament protein homologues of filensin, lamin and keratin; putative actin-binding homologues of ERM (ezrin/radixin/moesin), periplakin, utrophin, tropomyosin and paramyosin, and putative MAP homologues of restin/CLIP-170 (cytoplasmic linker protein-170). We suggest that the AtFPP (Arabiopsis thaliana filament-like plant protein) and AtMAP70 (Arabidopsis microtubule-associated protein 70) families of coiled-coil proteins may, in fact, be related to lamins and function as intermediate filament proteins.

Arabidopsis CROWDED NUCLEI (CRWN) proteins are required for nuclear size control and heterochromatin organization

“…Recent analysis based on secondary structure for analogues of Arabidopsis coiled-coil proteins indicates that CRWN proteins are candidates for paramyosin homologues [11]. Paramyosin is a structural protein found in invertebrate muscles, where it forms the core of thick filaments and bundles with myosin motors.…”

“…Although NMCP1 and related proteins are plant-specific and share no significant amino acid similarity to lamins, their tripartite structure with an extensive central coiled-coil domain and their localization at the nuclear periphery suggest that NMCP1-related plant proteins might be functional analogs of this core component of the animal nuclear lamina [9,10]. More recent computational analysis [11], however, has suggested that the NMCP class of plant proteins shares more structural similarities to myosins or paramyosins than to lamins.…”

Overexpressed TPX2 causes ectopic formation of microtubular arrays in the nuclei of acentrosomal plant cells

“…In metazoans, coiled-coil proteins group as various cytoskeletal networks comprising intermediate filament proteins, actin-binding proteins, and microtubule-associated proteins (Burkhard et al , 2001; Korolev et al , 2005). Albeit several proteins closely related to the intermediate filament protein were identified in silico (Gardiner et al , 2011), knowledge of plant coiled-coil proteins is limited. The current work found that overproduced AtTPX2 accumulated in interphase nuclei and observed TPX2-dependent fibrillar arrays interconnecting nuclei with the nuclear periphery.…”

Mechanisms for shaping, orienting, positioning and patterning plant secondary cell walls

“…Interestingly, a recent paper suggested that AtMAP70 may be related to animal intermediate filaments. 19 In plants, MAP70s are organized into a small multigenic family ranging from two isoforms in Selaginella sp. to ten in Glycine max (Fig.…”