Divergent FH2 domains of nematode FOZI-1-like proteins belong to the FMNL subtype.

<p><b>(A) Domain organizations of conventional nematode FMNL homologs and FOZI-1-related proteins.</b> Predicted structural domains are shown for FMNL-subtype FH2 domain-containing proteins from <i>M</i>. <i>musculus</i> (Mm) and five nematodes, <i>A</i>. <i>suum</i> (As), <i>C</i>. <i>elegans</i> (Ce), <i>S</i>. <i>ratti</i> (Sr), <i>R</i>. <i>culicivorax</i> (Rc), and <i>T</i>. <i>suis</i> (Ts). The nematode proteins fall into two classes. The conventional FMNL proteins largely resemble <i>M</i>. <i>musculus</i> FMNL1 with a Drf-type N-terminal domain organization (G-DID-DD) and pair of WH2/DAD-like motifs (red bars) C-terminal to the FH2 domain. The second set of proteins, including <i>C</i>. <i>elegans</i> FOZI-1, have N-terminal zinc fingers (ZF) followed by a C-terminal FH2 domain and no additional formin homology. The scale bar indicates protein length in amino acid residue number. <b>(B) ML phylogenetic tree of full-length nematode and other bilaterian FH2 domain sequences.</b> The evolutionary history for 93 FH2 domain sequences from five nematodes belonging to two orders (chromadorea and enoplea), and from six non-nematode bilaterians, was inferred by the ML method for 280 amino acid positions fully occupied in all sequences. All bootstrap values are indicated, and the scale bar indicates the number of substitutions per site for branch lengths. All nematode FH2 domains fell within one of the nine subtypes. Within the FMNL subtype, the divergent FOZI-1-related proteins of the chromadorean nematodes formed a subgroup that was positioned closely to the chromadorean conventional FMNL formins.