Gage MJ, Robinson AS. C-terminal hydrophobic interactions play a critical role in oligomeric assembly of the P22 tailspike trimer.
Protein Sci 2003;
12:2732-47. [PMID:
14627734 PMCID:
PMC2366982 DOI:
10.1110/ps.03150303]
[Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2003] [Revised: 09/08/2003] [Accepted: 09/08/2003] [Indexed: 10/26/2022]
Abstract
The tailspike protein from the bacteriophage P22 is a well characterized model system for folding and assembly of multimeric proteins. Folding intermediates from both the in vivo and in vitro pathways have been identified, and both the initial folding steps and the protrimer-to-trimer transition have been well studied. In contrast, there has been little experimental evidence to describe the assembly of the protrimer. Previous results indicated that the C terminus plays a critical role in the overall stability of the P22 tailspike protein. Here, we present evidence that the C terminus is also the critical assembly point for trimer assembly. Three truncations of the full-length tailspike protein, TSPDeltaN, TSPDeltaC, and TSPDeltaNC, were generated and tested for their ability to form mixed trimer species. TSPDeltaN forms mixed trimers with full-length P22 tailspike, but TSPDeltaC and TSPDeltaNC are incapable of forming similar mixed trimer species. In addition, mutations in the hydrophobic core of the C terminus were unable to form trimer in vivo. Finally, the hydrophobic-binding dye ANS inhibits the formation of trimer by inhibiting progression through the folding pathway. Taken together, these results suggest that hydrophobic interactions between C-terminal regions of P22 tailspike monomers play a critical role in the assembly of the P22 tailspike trimer.
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