Crystal structure of the 30 K protein from the silkworm Bombyx mori reveals a new member of the β-trefoil superfamily

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• 作者：Jie-Pin Yang^a ; Xiao-Xiao Ma^a ; Yong-Xing He^a ; Wei-Fang Li^a ; Yan Kang^a ; Rui Bao^a ; Yuxing Chen ; ^a ; ^{cyxing@ustc.edu.cn"" rel=""nofollow} ; Cong-Zhao Zhou ; ^a ; ^{zcz@ustc.edu.cn"" rel=""nofollow}
• 关键词：Silkworm ; Crystal structure ; 30 K proteins ; β ; -Trefoil superfamily ; Sugar-binding site
• 刊名：Journal of Structural Biology
• 出版年：2011
• 出版时间：July 2011
• 年：2011
• 卷：175
• 期：1
• 页码：97-103
• 全文大小：2062 K

文摘

The hemolymph of the fifth instar larvae of the silkworm Bombyx mori contains a group of homologous proteins with a molecular weight of approximately 30 kDa, termed B. mori low molecular weight lipoproteins (Bmlps), which account for about 5 % of the total plasma proteins. These so-called “30 K proteins” have been reported to be involved in the innate immune response and transportation of lipid and/or sugar. To elucidate their molecular functions, we determined the crystal structure of a 30 K protein, Bmlp7, at 1.91 Å. It has two distinct domains: an all-α N-terminal domain (NTD) and an all-β C-terminal domain (CTD) of the β-trefoil fold. Comparative structural analysis indicates that Bmlp7 represents a new family, adding to the 14 families currently identified, of the β-trefoil superfamily. Structural comparison and simulation suggest that the NTD has a putative lipid-binding cavity, whereas the CTD has a potential sugar-binding site. However, we were unable to detect the binding of either lipid or sugar. Therefore, further investigations are needed to characterize the molecular function of this protein.