2.1.1.170 malfunction construction of an rsmG null allele by deleting the rsmG coding sequence and replacing it with htk, encoding a heat-stable kanamycin adenyltransferase. This null allele retains the very N- and C-terminal rsmG coding sequences, in-frame with the htk coding sequence, in order to maintain the rsmG–parA overlap and minimize any effects on parA expression. This allele is designated DrsmGThtk2 and the mutant containing this allele is designated HG 917. Thermus thermophilus rsmG mutants are weakly resistant to the aminoglycoside antibiotic streptomycin. Growth competition experiments indicate a physiological cost to loss of RsmG activity, consistent with the conservation of the modification site in the decoding region of the ribosome -, 706725 2.1.1.170 malfunction enzyme loss confers low-level streptomycin resistance and may affect ribosomal functioning 733472 2.1.1.170 malfunction loss of the m7G527 modification confers low-level streptomycin resistance and may affect ribosomal functioning 721042 2.1.1.170 malfunction mutations within the gene gidB confer low-level streptomycin resistance. gidB Mmutations emerge spontaneously at a high frequency of 0.000001 and, once emerged, result in vigorous emergence of high-level streptomycin-resistant mutants at a frequency more than 2000 times greater than that seen in wild-type strains -, 705767 2.1.1.170 malfunction that the DELTArsmG mutant lacks a 7-methylguanosine modification in the 16S rRNA (possibly at position G518, which corresponds to G527 of Escherichia coli). The DELTArsmG mutant exhibits enhanced protein synthetic activity during the late growth phase. The DELTArsmG mutant shows neither greater stability of the 70S ribosomal complex nor increased expression of ribosome recycling factor -, 704272 2.1.1.170 malfunction the rsmG mutants are as fit as the wild-type strain under the various culture conditions tested -, 704273 2.1.1.170 malfunction the rsmG mutants show impaired ability to form aerial mycelia, and are somewhat deficient in sporulation. rsmG mutants show greater ability (two- to threefold) to produce streptomycin. The rsmG mutant exhibits elevated levels of metK, strR, strB1, strF and strD expression compared with the wild-type strain at late growth phase (36 h), thus underlying the enhanced production of streptomycin in the rsmG mutant. rsmG mutation is effective not only for enhancement of streptomycin production but also for activation of silent or poorly expressed genes in Streptomyces griseus -, 704222 2.1.1.170 additional information positively charged residues on the protein surface around the active site, K100/R101, R123, K165, and R197, might play a role in the binding of the incoming 530 loop since their change to alanine impairs the modification function of RsmG 721042 2.1.1.170 physiological function RsmG is an S-adenosyl-L-methionine-dependent methyltransferase responsible for the synthesis of m7G527 in the 530 loop of bacterial 16S rRNA. This loop is universally conserved, plays a key role in ribosomal accuracy, and is a target for streptomycin binding, mechanisms controlling RsmG expression and activity, overview. Gene rsmG as part of a bicistronic operon also has its own promoter, which appears, in actively growing cells, as a control device to offset both the relatively low stability of RsmG and inhibition of the operon promoter. Critical importance of some residues located in the active site of Escherichia coli RsmG for the m7G modification process, the residues play a role in rRNA binding and catalysis 721042