A gene, yaeQ, that suppresses reduced operon expression caused by mutations in the transcription elongation gene rfaH in Escherichia coli and Salmonella typhimurium

1998 ◽  
Vol 257 (6) ◽  
pp. 693-696 ◽  
Author(s):  
K. R. Wong ◽  
C. Hughes ◽  
V. Koronakis
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Transcription Elongation ◽  
Operon Expression

scholarly journals Deletion Formation Between the Two Salmonella typhimurium Flagellin Genes Encoded on the Mini F Plasmid: Escherichia coli ssb Alleles Enhance Deletion Rates and Change Hot-Spot Preference for Deletion Endpoints

Genetics ◽  
1997 ◽  
Vol 145 (3) ◽  
pp. 563-572 ◽  
Author(s):  
Takafumi Mukaihara ◽  
Masatoshi Enomoto
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Hot Spots ◽  
Hot Spot ◽  
Direct Repeats ◽  
Replication Slippage ◽  
Detection Systems ◽  
Deletion Formation ◽  
Homologous Sequences ◽  
Deletion Detection

Deletion formation between the 5′-mostly homologous sequences and between the 3′-homeologous sequences of the two Salmonella typhimurium flagellin genes was examined using plasmid-based deletion-detection systems in various Escherichia coli genetic backgrounds. Deletions in plasmid pLC103 occur between the 5′ sequences, but not between the 3′ sequences, in both RecA-independent and RecA-dependent ways. Because the former is predominant, deletion formation in a recA background depends on the length of homologous sequences between the two genes. Deletion rates were enhanced 30- to 50-fold by the mismatch repair defects, mutS, mutL and uvrD, and 250-fold by the ssb-3 allele, but the effect of the mismatch defects was canceled by the ΔrecA allele. Rates of the deletion between the 3′ sequences in plasmid pLC107 were enhanced 17- to 130-fold by ssb alleles, but not by other alleles. For deletions in pLC107, 96% of the endpoints in the recA+ background and 88% in ΔrecA were in the two hot spots of the 60- and 33-nucleotide (nt) homologous sequences, whereas in the ssb-3 background >50% of the endpoints were in four- to 14-nt direct repeats dispersed in the entire 3′ sequences. The deletion formation between the homeologous sequences is RecA-independent but depends on the length of consecutive homologies. The mutant ssb allele lowers this dependency and results in the increase in deletion rates. Roles of mutant SSB are discussed with relation to misalignment in replication slippage.

scholarly journals Autophagy—A Story of Bacteria Interfering with the Host Cell Degradation Machinery

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 110
Author(s):  
Anna K. Riebisch ◽  
Sabrina Mühlen ◽  
Yan Yan Beer ◽  
Ingo Schmitz
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Immune Response ◽  
Mycobacterium Tuberculosis ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Innate Immune ◽  
Intracellular Pathogens ◽  
Response Mechanism ◽  
Pathogenic Escherichia Coli

Autophagy is a highly conserved and fundamental cellular process to maintain cellular homeostasis through recycling of defective organelles or proteins. In a response to intracellular pathogens, autophagy further acts as an innate immune response mechanism to eliminate pathogens. This review will discuss recent findings on autophagy as a reaction to intracellular pathogens, such as Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, and pathogenic Escherichia coli. Interestingly, while some of these bacteria have developed methods to use autophagy for their own benefit within the cell, others have developed fascinating mechanisms to evade recognition, to subvert the autophagic pathway, or to escape from autophagy.

How Optimized Is the Translational Machinery in Escherichia coli, Salmonella typhimurium and Saccharomyces cerevisiae?

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Xuhua Xia
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Salmonella Typhimurium ◽  
Codon Usage ◽  
Translational Efficiency ◽  
Square Root ◽  
Translational Machinery ◽  
Mutual Adaptation ◽  
Trna Species

Abstract The optimization of the translational machinery in cells requires the mutual adaptation of codon usage and tRNA concentration, and the adaptation of tRNA concentration to amino acid usage. Two predictions were derived based on a simple deterministic model of translation which assumes that elongation of the peptide chain is rate-limiting. The highest translational efficiency is achieved when the codon recognized by the most abundant tRNA reaches the maximum frequency. For each codon family, the tRNA concentration is optimally adapted to codon usage when the concentration of different tRNA species matches the square-root of the frequency of their corresponding synonymous codons. When tRNA concentration and codon usage are well adapted to each other, the optimal content of all tRNA species carrying the same amino acid should match the square-root of the frequency of the amino acid. These predictions are examined against empirical data from Escherichia coli, Salmonella typhimurium, and Saccharomyces cerevisiae.

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