Properties of Bacteriophage T4 Baseplate Protein Encoded by Gene 8

M. M. Shneider^1*, S. P. Boudko^1,2, A. Lustig², and V. V. Mesyanzhinov¹

¹Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, ul. Miklukho-Maklaya 16/10, Moscow, 117871 Russia; fax: (095) 336-6022; E-mail: shneider@mail.ibch.ru

²Biozentrum, University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland

^* To whom correspondence should be addressed.

Received November 30, 2000

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Gene product 8 (gp8, 344 amino acids per monomer) of bacteriophage T4 is one of the baseplate structural proteins. We constructed an expression vector of gp8 and developed a method for purification of recombinant protein. CD spectroscopy showed that gp8 is an alpha/beta type structural protein. Its polypeptide chain consists of nearly 40% beta-structure and 15% alpha-helix. These data agree with results of prediction of secondary structure based on the amino acid sequence of the protein. The sedimentation coefficient under standard conditions (S_20,w) is 4.6S. Analytical ultracentrifugation results demonstrated that gp8 in solution has two types of oligomers--dimer and tetramer. The tetramer of gp8 may be included in the wedge (1/6 of the baseplate), and the dimer may be an intermediate product of association.

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KEY WORDS: bacteriophage T4, baseplate, gene product 8, CD spectroscopy, alpha/beta proteins

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