Formins are evolutionarily conserved multi-domain proteins participating in the control of both actin and microtubule dynamics. Angiosperm formins form two evolutionarily distinct families, Class I and Class II, with class-specific domain layouts. The model plant Arabidopsis thaliana has 21 formin-encoding loci, including 10 Class II members. In this study, we analyze the subcellular localization of two A. thaliana Class II formins exhibiting typical domain organization, the so far uncharacterized formin AtFH13 (At5g58160) and its distant homolog AtFH14 (At1g31810), previously reported to bind microtubules. Fluorescent protein-tagged full length formins and their individual domains were transiently expressed in Nicotiana benthamiana leaves under the control of a constitutive promoter and their subcellular localization (including co-localization with cytoskeletal structures and the endoplasmic reticulum) was examined using confocal microscopy. While the two formins exhibit distinct and only partially overlapping localization patterns, they both associate with microtubules via the conserved formin homology 2 (FH2) domain and with the periphery of the endoplasmic reticulum, at least in part via the N-terminal PTEN (Phosphatase and Tensin)-like domain. Surprisingly, FH2 domains of AtFH13 and AtFH14 can form heterodimers in the yeast two-hybrid assay-a first case of potentially biologically relevant formin heterodimerization mediated solely by the FH2 domain.

• Klíčová slova
• At1g31810, At5g58160, AtFH13, AtFH14, FH2 domain, PTEN-like domain, class II formin, confocal laser scanning microscopy,
• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• dimerizace MeSH
• endoplazmatické retikulum metabolismus   MeSH
• exprese genu MeSH
• forminy genetika   metabolismus   MeSH
• mikrotubuly metabolismus   MeSH
• proteinové domény MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• rekombinantní proteiny genetika   metabolismus   MeSH
• tabák metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• forminy MeSH
• proteiny huseníčku MeSH
• rekombinantní proteiny MeSH

The cytoskeleton plays a central part in spatial organization of the plant cytoplasm, including the endomebrane system. However, the mechanisms involved are so far only partially understood. Formins (FH2 proteins), a family of evolutionarily conserved proteins sharing the FH2 domain whose dimer can nucleate actin, mediate the co-ordination between actin and microtubule cytoskeletons in multiple eukaryotic lineages including plants. Moreover, some plant formins contain transmembrane domains and participate in anchoring cytoskeletal structures to the plasmalemma, and possibly to other membranes. Direct or indirect membrane association is well documented even for some fungal and metazoan formins lacking membrane insertion motifs, and FH2 proteins have been shown to associate with endomembranes and modulate their dynamics in both fungi and metazoans. Here we summarize the available evidence suggesting that formins participate in membrane trafficking and endomembrane, especially ER, organization also in plants. We propose that, despite some methodological pitfalls inherent to in vivo studies based on (over)expression of truncated and/or tagged proteins, formins are beginning to emerge as candidates for the so far somewhat elusive link between the plant cytoskeleton and the endomembrane system.

• MeSH
• intracelulární membrány metabolismus   MeSH
• mikrofilamenta metabolismus   MeSH
• proteiny asociované s mikrotubuly chemie   genetika   metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• proteiny huseníčku chemie   genetika   metabolismus   MeSH
• rostlinné buňky metabolismus   MeSH
• transport proteinů MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• FH16 protein, Arabidopsis MeSH Prohlížeč
• FH5 protein, Arabidopsis MeSH Prohlížeč
• proteiny asociované s mikrotubuly MeSH
• proteiny buněčného cyklu MeSH
• proteiny huseníčku MeSH

Formins are evolutionarily conserved eukaryotic proteins participating in actin and microtubule organization. Land plants have three formin clades, with only two - Class I and II - present in angiosperms. Class I formins are often transmembrane proteins, residing at the plasmalemma and anchoring the cortical cytoskeleton across the membrane to the cell wall, while Class II formins possess a PTEN-related membrane-binding domain. Lower plant Class III and non-plant formins usually contain domains predicted to bind RHO GTPases that are membrane-associated. Thus, some kind of membrane anchorage appears to be a common formin feature. Direct interactions between various non-plant formins and integral or peripheral membrane proteins have indeed been reported, with varying mechanisms and biological implications. Besides of summarizing new data on Class I and Class II formin-membrane relationships, this review surveys such "non-classical" formin-membrane interactions and examines which, if any, of them may be evolutionarily conserved and operating also in plants. FYVE, SH3 and BAR domain-containing proteins emerge as possible candidates for such conserved membrane-associated formin partners.

• Klíčová slova
• actin, cell polarity, endocytosis, endomembranes, formin, plasmalemma, vesicle trafficking,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH