Structural and functional diversification of HORMA domain‐containing proteins

Abstract

HORMA domain-containing proteins play important roles in cell cycle regulation and DNA repair, acting as adaptors to recruit other proteins. Although containing the conserved HORMA domain in structure, different types of HORMA proteins have diverged significantly in function. The mechanisms underlying the evolution and functional diversification of HORMA proteins remain unclear. Here we conduct an integrative approach, combining sequence, structural, gene coexpression and protein-protein interaction data, to trace the structural and functional evolution of HORMA proteins. Comparative sequence and structure analysis revealed that variations in both amino acid sequence and domain composition contributed to the functional diversification of different HORMA domaincontaining proteins. Multiple amino acid substitutions at the C-terminal region promoted the functional divergence between MAD2 and REV7 by facilitating interaction with different partners. The emergence of the HOP1CTD domain contributed to the function of HOP1 as a meiosis-specific structural component of the lateral elements of the synaptonemal complex. Additionally, different types of HORMA proteins were recruited into different functional modules in the genetic network while functioning distinctly.Key words: Gene coexpression, HORMA proteins, protein-protein interaction, structure-function relationship.The HORMA domain was named after the proteins HOP1, REV7, and MAD2, which were first identified in the yeast Saccharomyces cerevisiae (Lawrence et al., 1985;Hollingsworth & Byers, 1989;Boguski et al., 1992). The typical HORMA domain consists of 180-240 amino acid residues and forms a b-sheet complex with associated a-helices (Aravind & Koonin, 1998). HORMA domain-containing proteins play important roles in cell cycle regulation and DNA repair, acting as adaptors to recruit other proteins. HOP1 is a meiosis-specific protein involved in synaptonemal complex assembly that is required for chiasma formation in meiotic recombination (Hollingsworth et al., 1990;Latypov et al., 2010). REV7 is a subunit of the DNA polymerase z that is involved in translesion DNA synthesis, and is required for DNA double-strand break (DSB) repair (Murakumo et al., 2000). MAD2 is a key component of the mitotic spindle assembly checkpoint complex, which prevents separation of the duplicated chromosomes until each chromosome is properly attached to the spindle apparatus (Kabeche & Compton, 2012;Zich et al., 2012).HORMA domain-containing proteins have been identified in a wide range of eukaryotes (Aravind & Koonin, 1998;Muniyappa et al., 2014). Based on amino acid sequence homology and domain architectures, HORMA domain-containing proteins can be divided into three distinct types: HOP1, REV7, and MAD2 types (Muniyappa et al., 2014). Sequences of the same type protein from different species may have different names (e.g., the HOP1 homologues from Arabidopsis ASY1, ASY2, and the mammalian HOP1 homologues HORMAD1, HORMAD2), but share similar structures. The MAD2-and REV7-type prot...

Comparative genomics of HORMA domain-containing proteins in prokaryotes and eukaryotes

“…This supports the suggestion that the eukaryotic mitotic spindle checkpoint might evolve from a similar cell cycle control mechanism during Chlamydial cell division. Alignment of eukaryotic HOP1, REV7 and MAD2 sequences, along with gene co-expression and protein-protein interaction data, provide evidence that the MAD2 gene may have evolved earlier than the REV7 and HOP1 genes, which the single-celled eukaryotes only possess the MAD2 gene [62].…”