• Maobin Fu

      Articles written in Journal of Biosciences

    • Signatures of positive selection in LY96 gene in vertebrates

      Tonghai Dou Maobin Fu Yixia Wang Yang Zhao Zhengshi Wang Zhengqian Bian Yan Zhou

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      As a secreted glycoprotein that binds to the extracellular domain of Toll-like receptor 4 (TLR4), Lymphocyte Antigen 96 (LY96), also called myeloid differentiation 2 (MD2), is required for the activation of TLR4 by lipopolysaccharide (LPS) and plays an important role in innate immunity, which is the first line of defence against microbial infections. Previous studies have proposed that mammalian toll-like receptors (TLRs) have evolved under diversifying selection due to their role in pathogen detection. Given the fact that LY96 is highly functionally linked to TLR4, it would be interesting to test whether LY96 is under the intense pressure of natural selection. To investigate the natural selection hypothesis, we compared the coding sequences from 13 vertebrates and evaluated the molecular evolution of LY96 gene in these species. Result shows that natural selection at exon 4 has indeed played a role in shaping the function of LY96 in the course of evolution. In addition to the study of Nakajima, we found the two branch nodes with Ka/Ks ratios greater than 1: the one leading to cow and pig and the other to rabbit and the primates.

    • Signatures of positive selection at hemopexin (PEX) domain of matrix metalloproteinase-9 (MMP-9) gene

      Yang Liu Yang Zhao Chunlei Lu Maobin Fu Tonghai Dou Xiaoming Tan

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      Matrix metalloproteinases-9 (MMP-9) is an important cancer-associated, zinc-dependent endopeptidase. To investigate the natural selection hypothesis of MMP-9, the orthologous sequences from 12 vertebrates were compared and a molecular evolution analysis was performed. Results suggest that amino acid residues present in the middle region of the protein are more selectively constrained, whereas amino acid residues in the C-terminal region of the MM~P-9 protein including exon 13 showed lowest conservation level in non-primate species, suggesting that it is an exon with fast evolving rate compared to the others analyzed. InterProScan analysis shows that exon 13 was located in hemopexin (PEX) domain of MM~P-9. Positive selection was detected in PEX domain of MMP-9 protein between human and other species, which indicates that selective pressure may play a role in shaping the function of MM~P-9 in the course of evolution.

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