Substitution in vivo of the holin inhibitor RI of bacteriophage T4 by the homologous protein of T-even phage RB69

Abstract

Lysis inhibition is the ability to delay lysis of a bacterial cell primarily infected by a T-even phage for several hours in response to secondary T-even phage adsorption. This phenomenon is a unique attribute of the T-even family of phages. Recently, it has been established that the interaction between the T holin and the holin inhibitor RI plays the major role in the mechanism of lysis inhibition of phage T4. Bacteriophage RB69 is a member of this family, yet the relation of RB69 to lysis inhibition is undefined. In the present study, we constructed a T4 mutant which had its lysis inhibition gene rI replaced by a homologous gene of the phage RB69. The lysis profile of the recombinant phage showed that the lysis of infected cells was delayed for several hours. This result indicates that protein RI of RB69 can effectively substitute the holin inhibitor RI of phage T4 in lysis inhibition. Keywords: bacteriophage RB69, lysis inhibition, holin inhibitor RI