PROTEIN SYNTHESIS IN PROTOPLASTS* 



S. Spiegelman 



Department of Bacteriology, University of Illinois 



Introduction 



Weibull (1953) observed that exposure of Bacillus 

 megaterium cells to lysozyme under hypertonic conditions 

 leads to the formation of structures he labelled as protoplasts. 

 Usually each rod-like cell yields two or three of the spherical 

 protoplasts. Osmotically stabilized suspensions of the proto- 

 plasts were metabolically active, possessing a high endogenous 

 respiration (Weibull, 1953) and capable of glucose oxidation 

 at constant rates for extended periods of time (Wiame, 

 Storck and Vanderwinckel, 1955). It was quite generally re- 

 cognized that a subcellular system had been uncovered which 

 could be potentially useful in the analysis of cell function. A 

 number of laboratories immediately undertook a study of 

 the synthetic capacity of protoplasts. It is the purpose of the 

 present paper to summarize the results obtained to date. 



The Synthetic Potentiality of Protoplasts 



While we shall be mainly concerned with the synthesis of 

 specific proteins, it is of interest to begin with studies demon- 

 strating that protoplasts can support rather involved and 

 extensive synthetic processes. It Was shown independently 

 in two laboratories (Brenner and Stent, 1955; Salton and 

 McQuillen, 1955) that bacteriophage multiplication occurs in 

 protoplasts of B. megaterium if the bacteria are infected or 

 induced prior to the removal of the cell wall. Virus yields 



* The original investigations described stemming from the author's labora- 

 tory were aided by grants from the National Cancer Institute of the U.S. 

 Public Health Service and from the Office of Naval Research. 



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