Analysis of the proteins synthesized in ultraviolet light-irradiated Escherichia coli following infection with the bacteriophages lambdadrifd 18 and lambdadfus-3

Abstract

The presence of EF-Tu, RNA polymerase subunit alpha, and EF-G on the lambdadfus-3 genome and EF-Tu, ribosomal proteins L7/L12, and RNA polymerase subunit beta on the lambdadrifd 18 genome has been confirmed using a two-dimensional gel electrophoresis technique sensitive to changes in isoelectric point and molecular weight. In this system two EF-Tu gene products could not be resolved. Following infection of ultraviolet light-irradiated Escherichia coli with either lambdadfus-3 or lambdadrifd18, the EF-Tu gene, tufA, near 65 minutes on the genetic map is expressed as 3-4 copies per EF-G molecule. The EF-Tu gene, tufB, near 79 minutes on the genetic map, is expressed at about one-third of this rate. alpha is expressed as 1 copy per EF-G molecule, beta as 0.14 per EF-G molecule and L7/L12 as 2.5 per EF-G. These figures compare well with the relative amounts found in exponentially-growing cells, in which the ratio of EF-Tu to EF-G is approximately 5. Almost 90% of the total number of proteins (calculated on a molecular weight basis) which theoretically can be encoded on the lambdadrifd18 have been identified on the two-dimensional gel.