Bioinformatics Analysis Of Leucine-rich Repeat Motifs Molecular And VLRs In The Lamprey

Vertebrates with jaws (ganthostomes) possess a remarkable adaptive immune system that can recognize and initiate a protective response against potentially lethal pathogens rapidly and effectively. Gnathostome vertebrates inhabit in an environment filled with complex and shifting population of microorganisms, so they need to defense them and survive. It has widely been accepted that Gnathostome vertebrates have immunoglobulin molecules which consisted of Ig domains. These molecules play a decisive role in the adaptive immune responses.Jawless vertebrates are the ancestors of gnathostome vertebrates in the perspective of biological evolution. The lampreys are modern representatives of the jawless vertebrates, which are thought to be the ancestor of jawed vertebrates. The researches which are on the characteristics of adaptive immune response, the important immune molecules and the immune response mechanism will enrich people's understanding of the adaptive immune. In this paper, we report a new type of variable lymphocyte receptors in the lampreys. By the method of bioinformatics, we compare three types of VLRs in the amino acid sequences and find LRR-NT and LRR-CT have a higher conservation. Molecular diversity of VLRs are determined by the inserted number and types of LRRs. We also predict the spatial structure of the molecular, curvature and hydrophobic characteristics of VLRs. According to the literature, the germline VLR gene and mature VLR gene are compared, then we find the possible mechanisms of the germline gene. We speculate that the mature process of germline VLR gene is mediate by the cytosine deaminase. There are two types of cytosine deaminase gene are retrieved in the lamprey genome database. GVFD residues are in the end of each LRR, so we infer cytosine deaminase can identified these nucleotide sequence which encode the conserved GVFD sequence. The dispersed LRRV germline gene can been identified and connected by cytosine deaminase. In the search process of the molecule which are contain LRR structure, we find LaTLRA / B and the platelet glycoprotein. Through sequence analysis and evolutionary tree construction confirmed that LaTLRA / B and the platelet glycoprotein have higher homology with jawed vertebrates, and they also have conserved motif in special position. The topology tree presented that VLRs family maybe family may have evolved from the GPIBA.