The Biochemical Requirements for Bacterial Division.

We are searching for biochemical events related to the process of bacterial division. Data obtained with intact bacteria, using inhibitors primarily, august that protein synthesis must occur through most of the division cycle in order that a bacterium can divide at the end of the cycle. Hence, one approach is to look for a protein that Is made throughout the division cycle and whose production is related to ability of the bacteria to divide. Dr Masayorl Inouye modified the ability of the bacterium Escherichia coli to divide, using mutants, inhibitors or nutritional deficiencies, and then looked for alterations in the pattern formed by electropharesis of membrane proteins on polyacrylamide gels. One protein peak on the gels was strongly increased whenever the cells Were prevented from dividing. We named this protein "X"; it has a molecular weight of about 50000. A role was sought for the protein made throughout the cycle but showing its effect only at the end, Earlier observations by Dr Helene Smith showed that brief heating of the bacteria, (16 min at 45 °C) produced synchronous cell division; heating delayed division in a way suggesting that a protein needed for division had been damaged and must be resynthesized before division occurs. Damage to this protein causes the celis to swell; this swelling appears to be the prime basis far the delay of cell division, as shown recently by Dr Po Chi Wu. The swelling caused by an osmotic shift similarly delayed cell division; a result that is support for this hypothesis. A model is proposed for the role of the X protein as a sort af "girdle" that must be built up during the cycle, and that constricts the cells at the time of division. [ABSTRACT FROM AUTHOR]