scholarly journals Identification of Cold Shock Gene Loci inSinorhizobium meliloti by Using a luxABReporter Transposon

2000 ◽  
Vol 66 (1) ◽  
pp. 401-405 ◽  
Author(s):  
Kevin P. O'Connell ◽  
Ann M. Gustafson ◽  
M. Deane Lehmann ◽  
Michael F. Thomashow
Keyword(s):  
Escherichia Coli ◽  
Sinorhizobium Meliloti ◽  
Cold Shock ◽  
Insertion Site ◽  
Temperature Shift ◽  
Rrna Genes ◽  
23S Rrna ◽  
Shock Gene ◽  
23S Rrna Genes ◽  
Transposon Insertions

ABSTRACT Using a luxAB reporter transposon, seven mutants ofSinorhizobium meliloti were identified as containing insertions in four cold shock loci. LuxAB activity was strongly induced (25- to 160-fold) after a temperature shift from 30 to 15°C. The transposon and flanking host DNA from each mutant was cloned, and the nucleic acid sequence of the insertion site was determined. Unexpectedly, five of the seven luxAB mutants contained transposon insertions in the 16S and 23S rRNA genes of two of the threerrn operons of S. meliloti. Directed insertion of luxAB genes into each of the three rrnoperons revealed that all three operons were similarly affected by cold shock. Two other insertions were found to be located downstream of a homolog of the major Escherichia coli cold shock gene,cspA. Although the cold shock loci were highly induced in response to a shift to low temperature, none of the insertions resulted in a statistically significant decrease in growth rate at 15°C.

scholarly journals Transcriptional Organization and Regulation of a Polycistronic Cold Shock Operon in Sinorhizobium meliloti RM1021 Encoding Homologs of the Escherichia coli Major Cold Shock Gene cspA and Ribosomal Protein GenerpsU

2000 ◽  
Vol 66 (1) ◽  
pp. 392-400 ◽  
Author(s):  
Kevin P. O'Connell ◽  
Michael F. Thomashow
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Protein ◽  
Sinorhizobium Meliloti ◽  
Cold Shock ◽  
Open Reading Frames ◽  
Mrna Accumulation ◽  
Transcription Analysis ◽  
E Coli ◽  
Shock Gene ◽  
Shock Locus

ABSTRACT A homolog of the major eubacterial cold shock gene cspAwas identified in Sinorhizobium meliloti RM1021 byluxAB reporter transposon mutagenesis. Here we further characterize the organization and regulation of this locus. DNA sequence analysis indicated that the locus includes three open reading frames (ORFs) encoding homologs corresponding to CspA, a novel 10.6-kDa polypeptide designated ORF2, and a homolog of the Escherichia coli ribosomal protein S21. Transcription analysis indicated that this locus produced two different-sized cspA-hybridizing transcripts upon cold shock, a 400-nucleotide (nt) RNA encodingcspA alone and a 1,000-nt transcript encodingcspA-ORF2-rpsU. The sizes of the transcripts agreed with the location of the transcription start site determined by primer extension and the locations of two putative transcriptional terminators. The promoter of the cspA-ORF2-rpsU locus had −10 and −35 elements similar to the E. coliς70 consensus promoter and, like the cspAlocus of E. coli, included an AT-rich region upstream of the −35 hexamer. The promoter of the S. meliloti cspAlocus was found to impart cold shock-induced mRNA accumulation. In addition, the 5′-untranslated region (5′ UTR) was found to increase the fold induction of cspA transcripts after cold shock and depressed the level of luxAB mRNA prior to cold shock, another feature similar to cspA regulation in E. coli. No “cold box” was identified upstream of the S. meliloti cspA gene, however, and there was no other obvious sequence identity between the S. meliloti 5′ UTR and that of E. coli. DNA hybridization analysis indicated that outside the cspA-ORF2-rpsU cold shock locus there are several additional cspA-like genes and a secondrpsU homolog.

scholarly journals Construction and Initial Characterization of Escherichia coli Strains with Few or No Intact Chromosomal rRNA Operons

1999 ◽  
Vol 181 (12) ◽  
pp. 3803-3809 ◽  
Author(s):  
Tsuneaki Asai ◽  
Ciarán Condon ◽  
Justina Voulgaris ◽  
Dmitry Zaporojets ◽  
Binghua Shen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Rrna Operon ◽  
Rrna Genes ◽  
23S Rrna ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Protein Ratio ◽  
23S Rrna Genes

ABSTRACT The Escherichia coli genome carries seven rRNA (rrn) operons, each containing three rRNA genes. The presence of multiple operons has been an obstacle to many studies of rRNA because the effect of mutations in one operon is diluted by the six remaining wild-type copies. To create a tool useful for manipulating rRNA, we sequentially inactivated from one to all seven of these operons with deletions spanning the 16S and 23S rRNA genes. In the final strain, carrying no intact rRNA operon on the chromosome, rRNA molecules were expressed from a multicopy plasmid containing a single rRNA operon (prrn). Characterization of these rrndeletion strains revealed that deletion of two operons was required to observe a reduction in the growth rate and rRNA/protein ratio. When the number of deletions was extended from three to six, the decrease in the growth rate was slightly more than the decrease in the rRNA/protein ratio, suggesting that ribosome efficiency was reduced. This reduction was most pronounced in the Δ7 prrn strain, in which the growth rate, unlike the rRNA/protein ratio, was not completely restored to wild-type levels by a cloned rRNA operon. The decreases in growth rate and rRNA/protein ratio were surprisingly moderate in the rrndeletion strains; the presence of even a single operon on the chromosome was able to produce as much as 56% of wild-type levels of rRNA. We discuss possible applications of these strains in rRNA studies.

scholarly journals Ribosomal Mutations in Arcanobacterium pyogenes Confer a Unique Spectrum of Macrolide Resistance

2004 ◽  
Vol 48 (3) ◽  
pp. 1021-1023 ◽  
Author(s):  
B. Helen Jost ◽  
Hien T. Trinh ◽  
J. Glenn Songer ◽  
Stephen J. Billington
Keyword(s):  
Escherichia Coli ◽  
Macrolide Resistance ◽  
Rrna Genes ◽  
23S Rrna ◽  
23S Rrna Genes ◽  
Arcanobacterium Pyogenes

ABSTRACT Four macrolide-resistant Arcanobacterium pyogenes isolates contained A2058T, A2058G, or C2611G (Escherichia coli numbering) mutations in their 23S rRNA genes. While these mutations conferred resistance to erythromycin, oleandomycin, and spiramycin, they did not confer resistance to tylosin.

Demonstration of the absence of intervening sequences within 23S rRNA genes fromCampylobacter lari

2009 ◽  
Vol 49 (4) ◽  
pp. 386-394 ◽  
Author(s):  
Akihiro Tazumi ◽  
Yuki Kakinuma ◽  
John E. Moore ◽  
Cherie B. Millar ◽  
Ikue Taneike ◽  
...  
Keyword(s):  
Rrna Genes ◽  
23S Rrna ◽  
Intervening Sequences ◽  
23S Rrna Genes

scholarly journals tRNA genes are found between the 16S and 23S rRNA genes in Bacillus subtilis

1982 ◽  
Vol 10 (5) ◽  
pp. 1607-1624 ◽  
Author(s):  
Kate Loughney ◽  
Elsebet Lund ◽  
James E. Dahlberg
Keyword(s):  
Bacillus Subtilis ◽  
Rrna Genes ◽  
23S Rrna ◽  
Trna Genes ◽  
23S Rrna Genes

scholarly journals Spontaneous Erythromycin Resistance Mutation in a 23S rRNA Gene, rrlA, of the Extreme Thermophile Thermus thermophilus IB-21

2001 ◽  
Vol 183 (14) ◽  
pp. 4382-4385 ◽  
Author(s):  
Steven T. Gregory ◽  
Jamie H. D. Cate ◽  
Albert E. Dahlberg
Keyword(s):  
Genetic Manipulation ◽  
Thermus Thermophilus ◽  
Resistance Mutation ◽  
Rrna Genes ◽  
23S Rrna ◽  
Rrna Gene ◽  
Erythromycin Resistance ◽  
23S Rrna Gene ◽  
Resistant Mutants ◽  
23S Rrna Genes

ABSTRACT Spontaneous, erythromycin-resistant mutants of Thermus thermophilus IB-21 were isolated and found to carry the mutation A2058G in one of two 23S rRNA operons. The heterozygosity of these mutants indicates that A2058G confers a dominant or codominant phenotype in this organism. This mutation provides a valuable tool for the genetic manipulation of the 23S rRNA genes ofThermus.

scholarly journals Heterogeneous Macrolide Resistance and Gene Conversion in the Pneumococcus

2006 ◽  
Vol 50 (1) ◽  
pp. 359-361 ◽  
Author(s):  
Nicole Wolter ◽  
Anthony M. Smith ◽  
David J. Farrell ◽  
Keith P. Klugman
Keyword(s):  
Streptococcus Pneumoniae ◽  
Gene Conversion ◽  
Clinical Isolate ◽  
Resistant Strain ◽  
Macrolide Resistance ◽  
Fitness Cost ◽  
Rrna Genes ◽  
23S Rrna ◽  
Resistant Phenotype ◽  
23S Rrna Genes

ABSTRACT A macrolide-resistant clinical isolate of Streptococcus pneumoniae with 23S rRNA mutations showed a heterogeneous phenotype and genotype. The mutant 23S rRNA genes from this isolate transformed susceptible strain R6 to resistance. Culture of resistant strain R6 in the absence of antibiotic pressure showed gene conversion to occur between the four 23S rRNA alleles, resulting in reversion to susceptibility with the resistant phenotype showing a fitness cost. These data explain the disappearance on subculture of heterogeneous macrolide resistance in the pneumococcus.

Analysis of 23S rRNA genes in metagenomes – A case study from the Global Ocean Sampling Expedition

2011 ◽  
Vol 34 (6) ◽  
pp. 462-469 ◽  
Author(s):  
Pelin Yilmaz ◽  
Renzo Kottmann ◽  
Elmar Pruesse ◽  
Christian Quast ◽  
Frank Oliver Glöckner
Keyword(s):  
Global Ocean ◽  
Rrna Genes ◽  
23S Rrna ◽  
Global Ocean Sampling ◽  
Ocean Sampling ◽  
23S Rrna Genes

scholarly journals Pathophysiology of Antibiotic Resistance: Clarithromycin

2000 ◽  
Vol 14 (10) ◽  
pp. 891-894 ◽  
Author(s):  
Diane E Taylor
Keyword(s):  
Inhibitory Concentration ◽  
Natural Transformation ◽  
Rrna Genes ◽  
23S Rrna ◽  
Cross Resistance ◽  
In Vitro Mutagenesis ◽  
Clarithromycin Resistance ◽  
23S Rrna Genes ◽  
H Pylori

Resistance ofHelicobacter pylorito antibiotics ranges from 3% to 10% and may exceed these levels in some countries. The pathophysiology of clarithromycin resistance is reviewed, including the mode of action by which the antibiotic inhibits protein synthesis and the mechanism of resistance, which involves a mutation at position 2142 or 2143 in the V loop domain of the 23S rRNA genes. Mutations of A2142G confer a higher minimum inhibitory concentration than mutations of A2143G. The former demonstrate cross-resistance to macrolide, lincosamide and streptogramin antibiotics, whereas the latter are susceptible to streptogramin B. In vitro mutagenesis combined with natural transformation were used to create several types of clarithromycin-resistant mutants.H pyloristrains with A2142G and A2143G mutations had a higher growth rate than those with A2142C, A2143 or A2142T mutations. Data from this study indicate why clarithromycin-resistant clinical isolates ofH pyloriare more likely to have A2142G or A2143G mutations and only occasionally A2142C mutations.

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