title: Over-synthesis and instability of sigma protein in a merodiploid strain of Escherichia coli.
abstract: We have used two different methods to study the rates of RNA polymerase subunit synthesis in haploid Escherichia coli K12, and a KLF10 rPOB, C+ merodiploid derivative, when grown in glucose-minimal medium at 37 degrees C. Our results indicate that the haploid strain produces beta, beta', alpha and sigma in the molar ratios 1.01:0.99: less than or equal to 2.90:0.26; and that all these subunits are reasonably stable during subsequent growth. The merodiploid produces alpha at the same rate as the haploid, beta and beta' at a 42% higher rate, and sigma at twice the rate. Some 40% of the newly synthesised beta and beta' is degraded within one hour; the residuum is as stable as in the haploid. Alpha is stable throughout. By contrast, sigma is subject to a marked and continuous turnover in the merodiploid. These results are discussed in terms of gene dosage and regulatory effects.
mesh_terms: D002876:Chromosomes, Bacterial; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis* / Q000235:genetics; D004586:Electrophoresis; D004792:Enzyme Precursors / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D007525:Isoelectric Focusing; D011003:Ploidies
chemical_list: D004792:Enzyme Precursors; D012321:DNA-Directed RNA Polymerases