Influence of mRNA determinants on translation initiation in Escherichia coli

Hartz, Dieter; McPheeters, David S.; Gold, Larry

doi:10.1016/0022-2836(91)90875-7

Cited by 97 publications

(81 citation statements)

References 38 publications

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“…Comparison of the wild-type gltA sequence with the one found in strain JE3777 revealed a single point mutation that converted the start methionine codon from ATG to GTG. Although GTG encodes for methionine, it is rarely used as the start codon in enteric bacteria (53), suggesting that strain JE3777 would make low levels of wild-type GltA protein because of the limited pools of the GTG-tRNA-Met. Hereafter, the allele in strain JE3777 is referred to as gltA GTG to distinguish it from mutations that alter the amino acid sequence of the wild-type GltA protein.…”

Section: -Methylcitrate a Potent Inhibitor Of Cell Growthmentioning

confidence: 99%

Studies of Propionate Toxicity in Salmonella enterica Identify 2-Methylcitrate as a Potent Inhibitor of Cell Growth

Horswill¹,

Dudding

Escalante‐Semerena

2001

Journal of Biological Chemistry

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Salmonella enterica serovar Typhimurium LT2 showed increased sensitivity to propionate when the 2-methylcitric acid cycle was blocked. A derivative of a prpC mutant (which lacked 2-methylcitrate synthase activity) resistant to propionate was isolated, and the mutation responsible for the newly acquired resistance to propionate was mapped to the citrate synthase (gltA) gene. These results suggested that citrate synthase activity was the source of the increased sensitivity to propionate observed in the absence of the 2-methylcitric acid cycle. DNA sequencing of the wild-type and mutant gltA alleles revealed that the ATG start codon of the wild-type gene was converted to the rare GTG start codon in the revertant strain. This result suggested that lower levels of this enzyme were present in the mutant. Consistent with this change, cell-free extracts of the propionate-resistant strain contained 12-fold less citrate synthase activity. This was interpreted to mean that, in the wild-type strain, high levels of citrate synthase activity were the source of a toxic metabolite. In vitro experiments performed with homogeneous citrate synthase enzyme indicated that this enzyme was capable of synthesizing 2-methylcitrate from propionyl-CoA and oxaloacetate. This result lent further support to the in vivo data, which suggested that citrate synthase was the source of a toxic metabolite.

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Section: -Methylcitrate a Potent Inhibitor Of Cell Growthmentioning

confidence: 99%

Studies of Propionate Toxicity in Salmonella enterica Identify 2-Methylcitrate as a Potent Inhibitor of Cell Growth

Horswill¹,

Dudding

Escalante‐Semerena

2001

Journal of Biological Chemistry

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“…These results, together with those from dnaX, demonstrate that the spacing between the SD sequence and the shift site is more flexible in the -1 dnaX frameshift case than in the +1 RF2 gene case. The longer spacers with dnaX approach or equal the number of nucleotides 5' of the coding site expected to be encompassed by the ribosome, on the basis of nuclease protection experiments (30,31), sequence nonrandomness around initiation codons (27), and toe-printing P-site experiments (13).…”

Section: Sd --Ccg--------sd --Tact--------sd --Tacc--------sd --Taccgmentioning

confidence: 99%

rRNA-mRNA base pairing stimulates a programmed -1 ribosomal frameshift

et al. 1994

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Base pairing between the 3' end of 16S rRNA and mRNA is shown to be important for the programmed -1 frameshifting utilized'in decoding the Escherchia coli dnaX gene. This pairing is the same as the ShineDalgarno pairing used by prokaryotic ribosomes in selection of translation initiators, but for frameshifting the interaction occurs within elongating ribosomes. For dnaX -1 frameshifting, the 3' base of the Shine-Dalgarno sequence is 10 nucleotides 5' of the shift site. Previously, Shine-Dalgarno rRNA-mRNA pairing was shown to stimulate the + 1 frameshifting necessary for decoding the release factor 2 gene. However, in the release factor 2 gene, the Shine-Dalgarno sequence is located 3 nucleotides 5' of the shift site. When the Shine-Dalgarno sequence is moved to the same position relative to the dnaX shift site, it is inhibitory rather than stimulatory.Shine-Dalgarno interactions by elongating ribosomes are likely to be used in stimulating -1 frameshifting in the decoding of a variety of genes.Programmed ribosomal frameshifting is used for a variety of purposes in the decoding of a significant minority of genes in probably all organisms (1). For instance, in decoding the Escherichia coli dnaX gene, half of the ribosomes frameshift internally in the coding sequence and terminate to yield a short product (4, 10, 36). Accessory mRNA sequence elements, stimulators, serve to elevate the level of frameshifting at the shift site. In all known cases of -1 frameshifting, the stimulators are 3' to the shift site. The only known 5' stimulator is involved in + 1 frameshifting. In decoding the E. coli polypeptide chain release factor 2 (RF2), a Shine-Dalgarno (SD)-like sequence 5' of the shift site base pairs with its complement near the 3' end of 16S rRNA (8,(39)(40)(41). This is the same interaction that is well known to be crucial in selection of ribosome initiation sites. It is also known that ribosome binding to SD sequences can be independent of initiation (32, 38; see also reference 14). The involvement of the internal SD sequence in RF2 frameshifting shows that elongating ribosomes must unexpectedly be able to continuously scan mRNA for potential pairing.In this paper, we show that an upstream SD-like interaction can also mediate -1 frameshifting, as in expression of E. coli dnaX, which encodes DNA polymerase III subunits. E. coli DNA polymerase III consists of three core subunits and seven accessory subunits (20). Of the seven accessory subunits, T and ry are both translated from the same dnaX transcript. T is the 71-kDa full-length product of the dnaX gene translated entirely in the zero frame. ry is produced by a remarkably efficient (-50%) -1 ribosomal frameshift. After translating two-thirds of the gene, half of the ribosomes slip from the zero to the -1 frame. One codon later, the shifted ribosomes reach a UGA stop codon and produce the y (47-kDa) subunit (4, 10, 36).To date, two essential elements of the dnaX -1 frameshifting have been identified. These two cis elements are an A AAA AAG heptanucleotide shift s...

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“…Many different N-terminal tags can confer the advantage of increased yield (Table 1), the only requirement being that ribosomes efficiently initiate translation at the N-terminal methionine residue of the tag. When problems arise, it is often because a secondary structure in the mRNA interferes with the binding of ribosomes [1]. Deleterious secondary structures are more likely to occur in conjunction with small N-terminal tags because shortrange RNA-RNA interactions tend to be more stable than long-range interactions.…”

Section: Introductionmentioning

confidence: 99%