Transformation of a Fragment of beta-Structural Bacteriophage T4 Adhesin to Stable alpha-Helical Trimer

K. A. Miroshnikov^1,2, N. V. Sernova², M. M. Shneider², and V. V. Mesyanzhinov^2*

¹Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky pr. 33, Moscow, 117071 Russia

²Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117871 Russia; fax: (095) 336-6022; E-mail: vvm@mail.ibch.ru

^* To whom correspondence should be addressed.

Received April 18, 2000; Revision received August 21, 2000

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Gene product 12 of bacteriophage T4, adhesin, serves to adhere the virus to host cells. Adhesin is a fibrous homotrimer, and a novel tertiary structure element, a beta-helix, is supposed to be a major structural feature of this protein. We have constructed two truncated gp12 mutants, 12N1 and 12N2, containing 221 and 135 N-terminal residues, respectively. When expressed in E. coli cells, these gp12 fragments formed labile beta-structural trimers. Another hybrid protein, 12FN, containing 179 N-terminal amino acid residues of gp12 fused to the C-terminal domain (31 amino acids) of T4 fibritin, was shown to have a trimeric proteolytically resistant alpha-helical structure. This structure is probably similar to that of fibritin, which has a triple alpha-helical coiled-coil structure. Hence, we have demonstrated the possibility of global transformation of fibrous protein structure using fusion with a C-terminal domain that initiates trimerization.

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KEY WORDS: bacteriophage T4, protein folding, adhesin, fibritin, protein engineering, fibrous proteins

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