Molecular Recognition of the Tes LIM2–3 Domains by the Actin-related Protein Arp7A

Abstract

Actin-related proteins (Arps) are a highly conserved family of proteins that have extensive sequence and structural similarity to actin. All characterized Arps are components of large multimeric complexes associated with chromatin or the cytoskeleton. In addition, the human genome encodes five conserved but largely uncharacterized “orphan” Arps, which appear to be mostly testis-specific. Here we show that Arp7A, which has 43% sequence identity with β-actin, forms a complex with the cytoskeletal proteins Tes and Mena in the subacrosomal layer of round spermatids. The N-terminal 65-residue extension to the actin-like fold of Arp7A interacts directly with Tes. The crystal structure of the 1–65Arp7A·LIM2–3Tes·EVH1Mena complex reveals that residues 28–49 of Arp7A contact the LIM2–3 domains of Tes. Two alanine residues from Arp7A that occupy equivalent apolar pockets in both LIM domains as well as an intervening GPAK linker that binds the LIM2–3 junction are critical for the Arp7A-Tes interaction. Equivalent occupied apolar pockets are also seen in the tandem LIM domain structures of LMO4 and Lhx3 bound to unrelated ligands. Our results indicate that apolar pocket interactions are a common feature of tandem LIM domain interactions, but ligand specificity is principally determined by the linker sequence.

TES inhibits colorectal cancer progression through activation of p38

“…Human TES localizes to the cytoplasm as a component of focal adhesions and cell-cell contacts [13–18]. It contains a PET domain (found in a limited number of proteins, function has not been clarified to date [17]) and three tandemly arranged LIM domains (protein-interaction motifs that bind a wide range of different proteins [39]).…”

“…It contains a PET domain (found in a limited number of proteins, function has not been clarified to date [17]) and three tandemly arranged LIM domains (protein-interaction motifs that bind a wide range of different proteins [39]). TES interacts with a series of cytoskeletal proteins, such as Arp7A, alphaII-spectrin, talin, zyxin, Mena, EVL (Ena/vasodilator-stimulated, phosphoprotein-like protein), and actin [13–18]. Deletion of TES increases cell motility and decreases cell-cell connections, whereas TES overexpression causes the opposite effects [16, 18, 40].…”

“…The human TESTIN gene, also known as TES, has been implicated in cancer due to its loss of expression in prostate cancer [11, 12], its presence at the sites of focal adhesions, and its role in cytoskeletal organization [13–18]. TES was mapped to a common fragile site at chromosome 7q31.1/2, designated as FRA7G.…”

“…It is localized in the cytoplasm as a component of focal adhesions and cell-cell connections [13–18]. Lack of TES mRNA expression was found in several cancer-derived cell lines, particularly hematopoietic, breast, prostate, and ovarian cancer cell lines as well as in primary tumors.…”

Anti-ACTL7a antibodies: a cause of infertility

“…This protein plays an important role in spermiogenesis, primarily in the structural morphogenesis of spermatozoa (20). In spermatids, ACTL7a forms a complex with the cytoskeletal proteins Tes and Mena (21). However, a functional role for ACTL7a in the fertilizing potential of mammalian spermatozoa has not been reported.…”