The speciation of conger eel galectins by rapid adaptive evolution

Abstract

Many cases of accelerated evolution driven by positive Darwinian selection are identified in the genes of venomous and reproductive proteins. This evolutional phenomenon might have important consequences in their gene-products' functions, such as multiple specific toxins for quick immobilization of the prey and the establishment of barriers to fertilization that might lead to speciation, and in the molecular evolution of novel genes. Recently, we analyzed the molecular evolution of two galectins isolated from the skin mucus of conger eel (Conger myriaster), named congerins I and II, by cDNA cloning and X-ray structural analysis, and we found that they have evolved in the rapid adaptive manner to emergence of a new structure including strand-swapping and a unique new ligand-binding site. In this review article we summarize and discuss the molecular evolution, especially the rapid adaptive evolution, and the structure-function relationships of conger eel galectins.

An Overview of the Immunological Defenses in Fish Skin

“…As the skin mucus is exposed to the surrounding outer environment, proteins in the skin mucus are required to maintain their activities under severe conditions such as higher temperature and hydraulic pressure [86]. Mucus is a viscid (sticky) gel; there are few surfaces to which it does not stick.…”

Molecular diversity of proteins in biological offense and defense systems

“…Many thanks are also extended to professor Dr. Shu-Kun Lin (Editor-in-Chief) for his assistance. Porin protein 1 Bacteria (Neisseria) [7] CSP, TRAP, MSA-2 & PF83 Protozoa [8] Resistance to antibiotics b-lactamase Bacteria (TEM) [9] Toxin Colicin Bacteria [10] Conotoxins GD Mollusc (Conus) [11 -14] Phospholipase A2/Serine protease/Zn protease/3 finger toxins/CTLP GD Reptile (Snake) [15 -20] Spider toxins/Scorpion toxins GD Arthropod [21 -24] Immunity Immunoglobulin VH GD Mammals [25] MHC GD Mammals [26] Enzyme inhibitors a1-Proteinase inhibitor GD Rodents [27] Elafin GD Mammals [28] Polygalacturonase inhibitor Plant (Legume) [29] Type I interferon-omega Mammals [30] Phospholipase A2 inhibitor GD Reptile (Snake) [31] Innate immunity Siglec GD Mammals [32] Class1 chitinase Plant (Arabidopsis) [33] Congerins GD Fish [34,35] Transferrin Fish [36] Defensin GD Mammals [37,38] RH, RH50 blood group GD Primates and rodents [39] RNase A GD Mammals [40,41] Cytidine deaminase Mammals [42] Reproduction Cell recognition 18-kDa fertilization protein/Sperm lysin/TMAP/lysine-R Mollusc (Haliotis) [43 -45] Bindin/suREJ Echinoderm [46,47] Protamine P1 Primates [48] ZP2/ZP3 Rodents [49] S-Rnase GD Plant [50] Reproduction behavior control Acp26Aa, Acp70A GD Drosophila [51] Androgen-binding protein Rodents [52] Reproductive transcription factor Sry gene Primates [53] Ods homeobox Drosophila [54] Pem homeobox GD Rodents [55] Others Transcription factor Asr2 Plant (Lycopersicon)…”

Lgals6, a 2-Million-Year-Old Gene in Mice: A Case of Positive Darwinian Selection and Presence/Absence Polymorphism

“…In the fish Conger myriaster, this is also the case for the galectin-1-related protein congerin-I. Since this protein is expressed in the fish's skin mucus cells, where it can recognize bacteria such as Vibrio anguillarum, it has been proposed that it might be involved in innate or acquired immunity through its agglutinating activity (Ogawa et al 2004). In rats, the Lgals5 gene derives from a recent duplication of the Lgals9 gene (Houzelstein et al 2004).…”