Two Clusters of Genes for RNA Polymerase and Ribosome Components in Escherichia coli

Abstract

INTRODUCTION
To understand the regulation of the biosynthesis of ribosomes, we have been investigating the organization of ribosomal protein (r-protein) genes in E. coli. Many r-protein genes in E. coli have been mapped near 64 minutes on the genetic map (Taylor and Trotter 1972) at the “str-spc” region (for a review, see Jaskunas, Nomura and Davies 1974). However, the structural gene for r-protein S18 has been mapped far from this cluster, at 84 minutes (Bollen et al. 1973; DeWilde, Michel and Broman 1974). Thus it seems possible that some of the unmapped r-protein genes are not part of the str-spc cluster.

Friesen et al. (1974) isolated and characterized a mutant of E. coli at the relC locus. The phenotype of this mutant suggested that the relC locus could be a structural gene for a 50S r-protein. Since the relC locus was mapped close to rif, the structural gene for the β subunit of RNA polymerase (Heil and Zillig 1970; di Mauro et al. 1969), we thought that the relC locus might be on λrif^d18, which carries bacterial DNA from this region of the E. coli chromosome (Kirschbaum and Konrad 1973).

Investigations of the genes on λrif^d 18 have revealed that this phage carries genes for several 50S r-proteins (Lindahl et al. 1975), a gene for elongation factor EF-Tu (tuf B) (Jaskunas et al. 1975) and genes for 16S, 23S and 5S rRNA and tRNA₂^Glu (Lindahl et al. 1975; Lund et al. 1976; Yamamoto, Lindahl and Nomura 1976), in addition to...