Biochemical characterization of an Escherichia coli hisT strain

Lawther, Robert P.; Hatfield, W

doi:10.1128/jb.130.1.552-557.1977

Cited by 34 publications

(11 citation statements)

References 16 publications

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“…It is clear from Table 2 that pE-directed expression of ilvE is negligible when cells are grown in LB-broth. This is consistent with previous results that show literally no ilvGMEDA expression in vivo when cells are grown in LB-broth (13,30,31). There appears to be a 40-60% repression of pE in the presence of ile, let and val, which is consistent with the results of Smith et al (8).…”

Section: Discussionsupporting

confidence: 93%

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Analysis and comparison of the internal promoter, pE, of the ilvGMEDA operons fromEscherichia coliK-12 andSalmonella typhimurium

Lopes¹,

Lawther²

1986

Nucl Acids Res

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It was previously determined that the distal portion of the ilvGMEDA operon was expressed despite the insertion of transposons into ilvG and ilvE. This observation suggested the existence of internal promoters upstream of ilvE (pE) and ilvD (pD). The internal promoter pE, responsible for part of ilvEDA expression, has been analyzed both in vivo and in vitro. Our results indicate that: pE exists in both E. coli K-12 and S. typhimurium; pE is located in the distal end of the ilvM coding sequence; the pE sequence is highly conserved in the two bacteria; the amino acid sequence of the ilvM gene product is 93% homologous between the two bacteria; transcription from pE can be demonstrated both in vivo and in vitro; the efficiency of pE is essentially equivalent in the two bacteria.

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Section: Discussionsupporting

confidence: 93%

“…leucine (leu) and valine (val). Furthermore, expression of the ilvGMEDA operon is almost completely repressed when cells are grown in LB-broth (13,30,31).…”

Section: Expression Of Transaminase B (Ilve) From Pementioning

confidence: 99%

Analysis and comparison of the internal promoter, pE, of the ilvGMEDA operons fromEscherichia coliK-12 andSalmonella typhimurium

Lopes¹,

Lawther²

1986

Nucl Acids Res

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“…It is also possible that translation, possibly of a portion of a his mRNA "leader" sequence extending from P1 to Atn, may play a role in the activation process (3,4). his operon regulation in Escherichia coli appears to proceed by mechanisms identical to those effective in S. typhimurium (8,18,24,28).…”

mentioning

confidence: 99%

“…Histidine input into the operon-attenuated control system depends strictly upon the concentration of charged, pseudouridine-modified tRNAHIS and not on total tRNAHiS or on free histidine (7,26). The regulatory system is essentially histidine independent in the absence of pseudouridine modifications in the tRNAH"' anticodon loop (7,26), modifications mediated by the hisT gene product (8,11,12,24,37). Thus, while the unmodified tRNAH'i apparently is unimpaired in protein synthesis and is charged normally with histidine (26), it appears relatively inefficient in histidine regulation.…”

mentioning

confidence: 99%

Promoter- and attenuator-related metabolic regulation of the Salmonella typhimurium histidine operon

Winkler¹,

Roth²,

Hartman³

1978

J Bacteriol

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Expression of the histidine (his) operon in Salmonella typhimurium was found to be positively correlated with the intracellular level of guanosine tetraphosphate (ppGpp). Limitation for amino acids other than histidine elicited a histidineindependent metabolic regulation of the operon. In bacteria grown at decreased growth rates, his operon expression was metabolically regulated up to a point, after which further decreases in growth rate no longer resulted in further enhancement of operon expression. Studies using strains carrying various regulatory and deletion mutations indicated that metabolic regulation is achieved predominantly by increased RNA chain initiations at the primary (P1) and internal (P2) promoters. Metabolic regulation ordinarily did not involve changes in RNA chain terminations at the attenuator site of the his operon. A model is proposed that involves ppGpp-induced changes in RNA polymerase initiation specificity at particular promoters. A second, special form of metabolic regulation may operate which also is histidine independent, but does involve relief of attenuation. Expression of the histidine (his) operon inSalmonella typhimurium is exerted predominantly at the level of mRNA production (22) and appears to involve two major control sites, the primary promoter (P1) and a transcriptional barrier called the attenuator (Atn) (3,22). Thus, overall operon expression involves both the frequency of RNA chain initiations at P1 and the frequency ofpremature RNA chain terminations at Atn (Fig. 1). Data obtained from in vivo and in vitro experiments indicate that mutation hisO2355 at least in part defines the P1 site and deletion hisO1242 defines the Atn site (13,15,22).The model also hypothesizes the existence of a positive factor (46), acting to relieve the transcriptional terminations otherwise occurring at the attenuator (anti-Atn). Three mutational sites, hisO2965, hisO2966, and hisO3148, seem to affect relief of attenuation (13, 22); thus, the site of positive-factor interaction is represented by the broad bracket labeled "Anti-Atn" in Fig.

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“…hisT strains of E. coli and S. typhinurium are defective in pseudouridylate synthetase, which leaves uridine in place of pseudouridine in the anticodon loop of leucyl-, histidyl-, and some other tRNA's (5). This modification alters the regulatory properties of the tRNA (10). In S. typhimurium, leucine transport in a hisT strain was at repressed levels without the addition of leucine and was not changed by leucine concentrations that repressed transport in a hisT strain (13).…”

Section: Fixation Of Nh4' Into Amino Acids Requiresmentioning

confidence: 98%

Repression of Escherichia coli pyridine nucleotide transhydrogenase by leucine

Gerolimatos¹,

Hanson²

1978

J Bacteriol

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Reteive,d forpublication 26 October. 1977 Addition of 0.1% casein hydrolysate to a iniiiimal growth medium decreased membrane-bound transhydrogenase activity in Escherichia coli by about 80%. Of the amino acids added individually to the growth medium, only leucine and, toa lesser extent, methionine and alanine were effective. a-Ketoisocaproateand leucine-containing'peptides repressed the activity, and leucine also repressed activity in adenyl cyclase-deficient and relaxed strains. Derepression of transhy

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Biochemical characterization of an Escherichia coli hisT strain

Abstract: An Escherichia coli hisT strain was characterized biochemically and shown to contain altered transfer ribonucleic acid and to be altered in the regulation of amino acid biosynthesis.

Cited by 34 publications

References 16 publications

Analysis and comparison of the internal promoter, pE, of the ilvGMEDA operons fromEscherichia coliK-12 andSalmonella typhimurium

Analysis and comparison of the internal promoter, pE, of the ilvGMEDA operons fromEscherichia coliK-12 andSalmonella typhimurium

Promoter- and attenuator-related metabolic regulation of the Salmonella typhimurium histidine operon

Repression of Escherichia coli pyridine nucleotide transhydrogenase by leucine

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