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Publication Abstract from PubMed

Interleukin-1 beta (IL-1beta) is an important cytokine in the immune system. The properties of avian IL-1betas are less well understood than the mammalian IL-1betas, and there is no available structure of avian IL-1betas in the Protein Data Bank. Here, we report the crystal structures of wild-type and Y157F mutant IL-1betas from chicken. Both the wild-type and mutant IL-1betas share a beta-trefoil conformation similar to that of human IL-1beta and also have an internal hydrophobic cavity. However, the cavity sizes clearly differ from that of human IL-1beta due to the packing of hydrophobic residues. Our studies also reveal that the relative thermal stability of IL-1betas does not correlate with cavity size but rather is dependent on the amino acid residues present around the cavity. This cavity serves as a scaffold for maintaining the structure of the IL-1beta core region but does not have a biological function per se. Moreover, we found that human IL-1beta cannot induce chemokine expression in chicken fibroblasts or elevate plasma cortisol levels in chickens, implying a lack of cross-species bioactivity. Close examination reveals that significant structural and sequence differences occur in the terminal and some loop regions between human and chicken IL-1betas. These variable regions have been shown to be critical for receptor binding, thus resulting in a lack of species cross-reactivity between human and chicken IL-1beta.

Structural and functional comparison of cytokine interleukin-1 beta from chicken and human.,Cheng CS, Chen WT, Lee LH, Chen YW, Chang SY, Lyu PC, Yin HS Mol Immunol. 2011 Mar;48(6-7):947-55. Epub 2011 Feb 1. PMID:21288573^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.