REGULATION OF TRANSCRIPTION FACTOR-RHO AND ALPHA-SUBUNIT OF RNA-POLYMERASE IN ESCHERICHIA-COLI B-R

Transcriptional termination factor .rho., the .alpha. subunit of RNA polymerase (RNA nucleotidyltransferase, nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6), and ribosomal protein S6 were resolved from whole-cell extracts of E. coli B/r by a high-resolution, 2-dimensional polyacrylamide gel electrophoretic technique, and were identified through coelectrophoresis with the purified proteins. The regulation of .rho., .alpha. and S6 was studied in steady-state cultures of E. coli B/r growing at rates of 0.6-2.1 generations/h by this gel technique and a double radioisotope labeling procedure. The regulatory patterns of .rho. and .alpha. are distinct from, but similar to, one another. Neither .rho. nor .alpha. shows the sharply increasing levels with increasing growth rate shown by the ribosomal proteins as exemplified by S6. The difference between the levels of .rho. and .alpha. and .rho. and S6, is most pronounced during rapid growth. The regulatory pattern of .alpha. is interesting, given the recent suggestion that the gene coding for .alpha. is cotranscribed with genes coding for ribosomal proteins.