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Journal of Bacteriology, December 2004, p. 8363-8369, Vol. 186, No. 24
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.24.8363-8369.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

In Vivo Bypass of Chaperone by Extended Coiled-Coil Motif in T4 Tail Fiber

Yun Qu,1,{dagger} Paul Hyman,1,{ddagger} Timothy Harrah,1,2 and Edward Goldberg1*

Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston,1 Department of Biomedical Engineering, Tufts University, Medford, Massachusetts2

Received 9 July 2004/ Accepted 15 September 2004

The distal-half tail fiber of bacteriophage T4 is made of three gene products: trimeric gp36 and gp37 and monomeric gp35. Chaperone P38 is normally required for folding gp37 peptides into a P37 trimer; however, a temperature-sensitive mutation in T4 (ts3813) that suppresses this requirement at 30°C but not at 42°C was found in gene 37 (R. J. Bishop and W. B. Wood, Virology 72:244-254, 1976). Sequencing of the temperature-sensitive mutant revealed a 21-bp duplication of wild-type gene 37 inserted into its C-terminal portion (S. Hashemolhosseini et al., J. Mol. Biol. 241:524-533, 1994). We noticed that the 21-amino-acid segment encompassing this duplication in the ts3813 mutant has a sequence typical of a coiled coil and hypothesized that its extension would relieve the temperature sensitivity of the ts3813 mutation. To test our hypothesis, we crossed the T4 ts3813 mutant with a plasmid encoding an engineered pentaheptad coiled coil. Each of the six mutants that we examined retained two amber mutations in gene 38 and had a different coiled-coil sequence varying from three to five heptads. While the sequences varied, all maintained the heptad-repeating coiled-coil motif and produced plaques at up to 50°C. This finding strongly suggests that the coiled-coil motif is a critical factor in the folding of gp37. The presence of a terminal coiled-coil-like sequence in the tail fiber genes of 17 additional T-even phages implies the conservation of this mechanism. The increased melting temperature should be useful for "clamps" to initiate the folding of trimeric ß-helices in vitro and as an in vivo screen to identify, sequence, and characterize trimeric coiled coils.

* Corresponding author. Mailing address: Tufts University School of Medicine, Dept. of Molecular and Microbiology, 146 Harrison Ave., Boston, MA 02111. Phone: (617) 636-6754. Fax: (617) 636-0337. E-mail: eddie.goldberg{at}tufts.edu.

{dagger} Present address: Altus Biologics, Inc., Cambridge, MA 02139.

{ddagger} Present address: The Ohio State University, Mansfield, OH 44906.

Journal of Bacteriology, December 2004, p. 8363-8369, Vol. 186, No. 24
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.24.8363-8369.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Wu, L.-T., Chang, S.-Y., Yen, M.-R., Yang, T.-C., Tseng, Y.-H. (2007). Characterization of Extended-Host-Range Pseudo-T-Even Bacteriophage Kpp95 Isolated on Klebsiella pneumoniae. Appl. Environ. Microbiol. 73: 2532-2540 [Abstract] [Full Text]  


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