Tail Tip Proteins Related to Bacteriophage λ gpL Coordinate an Iron-Sulfur Cluster

JOURNAL OF MOLECULAR BIOLOGY

卷:425

Article

Tam, William¹  Pell, Lisa G.²  Bona, Diane³  Tsai, Alex¹  Dai, Xiao Xian⁴  Edwards, Aled M.²  Hendrix, Roger W.⁴  Maxwell, Karen L.^2,3  Davidson, Alan R.^1,2 

[1] Univ Toronto, Dept Biochem, Toronto, ON M5S 1A8, Canada

[2] Univ Toronto, Dept Mol Genet, Toronto, ON M5S 1A8, Canada

[3] Univ Toronto, Donnelly Ctr Cellular & Biomol Res, Toronto, ON M5S 3E1, Canada

[4] Univ Pittsburgh, Dept Biol Sci, Pittsburgh, PA 15260 USA

关键词: bacteriophage;    iron-sulfur cluster;    phage tail assembly;    phage lambda gpL;   

DOI  :  10.1016/j.jmb.2013.03.032

来源: Elsevier

【 摘 要 】

The assembly of long non-contractile phage tails begins with the formation of the tail tip complex (TTC). TTCs are multi-functional protein structures that mediate host cell adsorption and genome injection. The TTC of phage lambda is assembled from multiple copies of eight different proteins, including gpL. Purified preparations of gpL and several homologues all displayed a distinct reddish color, suggesting the binding of iron by these proteins. Further characterization of the gpL homologue from phage N15, which was most amenable to in vitro analyses, showed that it contains two domains. The C-terminal domain was demonstrated to coordinate an iron-sulfur cluster, providing the first example of a viral structural protein binding to this type of metal group. We characterized the iron-sulfur cluster using inductively coupled plasma-atomic emission spectroscopy, absorbance spectroscopy, and electron paramagnetic resonance spectroscopy and found that it is an oxygen-sensitive [4Fe-4S](2+) cluster. Four highly conserved cysteine residues were shown to be required for coordinating the iron-sulfur cluster, and substitution of any of these Cys residues with Ser or Ala within the context of lambda gpL abolished biological activity. These data imply that the intact iron-sulfur cluster is required for function. The presence of four conserved Cys residues in the C-terminal regions of very diverse gpL homologues suggest that utilization of an iron-sulfur cluster is a widespread feature of non-contractile tailed phages that infect Gram-negative bacteria. In addition, this is the first example of a viral structural protein that binds an iron-sulfur cluster. (C) 2013 Elsevier Ltd. All rights reserved.

【 授权许可】

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