Novel subfamilies of actin-regulating proteins.

Ability of actin to polymerise and depolymerise makes it essential to key functions of eukaryotic cell. The functioning of actin is controlled by a host of regulatory proteins, the repertoire of which in diatoms is known to remarkably differ from other organisms. We have performed a phylogenetic analysis of 521 actin and actin-related proteins' aminoacid sequences, as well as 190 sequences of gelsolin family proteins from various genomic and transcriptomic datasets. Based on the results of this analysis, as well as on the presence of clade-specific indels in some of the actin-related proteins, we describe a novel ARP subfamily, dubbed ARP12, which is specific to heterokonts and related organisms. We also describe two novel diatom-specific subfamilies, dGRC1 and dGRC2, among short gelsolin repeat-containing proteins.