Amino Acid Transport in Bacteria

Haney, Steven; Oxender, Dale L.

doi:10.1016/s0074-7696(08)62673-x

Cited by 17 publications

(7 citation statements)

References 177 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A previous report described the cloning of a gene that complemented the livR phenotype (4). This gene was subsequently found to map near min 18 (3), and its role in regulation of high-affinity transport of leucine is likely posttranscriptional (8).…”

mentioning

confidence: 99%

Lrp, a leucine-responsive protein, regulates branched-chain amino acid transport genes in Escherichia coli

et al. 1992

View full text Add to dashboard Cite

Branched-chain amino acids are transported into Escherichia coli by a low-affinity system, LIV-II, and by two high-affinity systems, 18). The latter two high-affinity systems are the focus of this paper. The LIV-I system transports leucine, isoleucine, and valine, whereas the LS system transports only leucine. The two systems have a common set of membrane components and are distinguished by the specificities of their periplasmic binding proteins (9). The LIV-I binding protein binds L-leucine, L-isoleucine, and L-valine with approximately equal affinity and is coded for by the livJ gene, whereas the LS binding protein binds D-and L-leucine but neither isoleucine nor valine and is coded for by livK, the first gene in an operon that also codes for the common membrane components. The genes are closely linked near min 76 on the E. coli chromosome within a region referred to as the LIV-I locus.The LIV-I locus is regulated by leucine, as determined by assaying the transport and leucine binding activities of periplasmic shock fluids (1,19 scribed and termed lrp (leucine-responsive regulatory protein) (11, 16). Mutations in lrp affect the expression of a number of operons, including ilvIH (16), serA (11,20), sdaA (11), tdh (11,20), and oppABCDF (5). The expression of each of these operons, like those composing the LIV-I locus, is altered by growing cells in the presence of leucine. Given the similarity in map location and the common connection to leucine, it seemed possible that livR and lrp are the same locus. Rex et al. raised this possibility recently in connection with studies showing that a livR allele had a dramatic effect upon the regulation of the tdh and serA operons (20). Here we show that livR and lrp are indeed the same gene. A livRJ-containing strain had mutations in lrp, and these mutations were shown to affect the expression of ilvIH, an operon known to be regulated by lrp. Moreover, lrp mutations that arose under conditions having nothing to do with amino acid transport were shown to affect the expression of livJ and livK.An important finding that came out of these studies is the amino acid transport phenotype of a strain with a null mutation in lrp. Such a strain shows high, constitutive transport of branched-chain amino acids. This result reflects the fact that expression from the livJ and livK promoters is similarly high and constitutive. These results suggest that Lrp, the product of lrp, negatively regulates livJ and livK expression. As we point out in the Discussion, a negative effect of lrp coupled with leucine-mediated repression is a pattern that is unique for operons known to be regulated by lrp.

show abstract

mentioning

confidence: 99%

Lrp, a leucine-responsive protein, regulates branched-chain amino acid transport genes in Escherichia coli

et al. 1992

View full text Add to dashboard Cite

show abstract

“…The pattern of uptake of amino acids may play an important role in the fermentation physiology. The regulation of uptake of nitrogen substrates has been studied extensively in prokaryotes,22–29 lower eukaryotes such as Saccharomyces cerevisiae 30–34 and the filamentous fungus Aspergillus nidulans 35–38. These organisms regulate the amino acid uptake through multiple amino acid transporters.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and thermal behavior of thermotropic terpolymers based on 8‐(3‐hydroxyphenyl)octanoic acid, 2,6‐naphthalenedicarboxylic acid, and substituted hydroquinones

Vijayanathan

Prasad

Pillai

2001

J of Applied Polymer Sci

View full text Add to dashboard Cite

Aromatic–aliphatic thermotropic liquid crystalline terpolyesters derived from 2,6‐naphthalenedicarboxylic acid, hydroquinones, and 8‐(3‐hydroxyphenyl)octanoic acid (HPOA), a monomer with built‐in kink and flexible moieties, were prepared by a melt polycondensation reaction. These polymers were characterized for their thermotropic liquid crystalline properties. The effect of variation in the composition of the polyester on the liquid crystalline behavior and thermal properties was also studied. Increasing the content of kinked units increased the amount of structural irregularity and decreased the isotropization temperature. The Tm and thermal stability of the polyesters were found to decrease with increase in the HPOA content. The formation of the liquid crystalline phase was not prevented by the introduction of up to 40 mol % of HPOA in the copolyester. The effect of substituents on the thermal properties of the terpolyesters was also studied. Introduction of a phenyl substituent on the hydroquinone ring was found to lower the transition temperature compared to substituents such as methyl or methoxy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1021–1029;2001

show abstract

“…The existence of this transporter was predicted earlier on the basis of detection of its function-transport of threonine in symport with sodium cation [170,171]. Targeted inactivation of the sstT gene is used in design ing threonine producing strains on the basis of a strain with a minimized genome (see below); however, the effect of its inactivation was not assessed [63].…”

Section: Threonine Transport Into a Cellmentioning

confidence: 99%

“…Targeted inactivation of the sstT gene is used in design ing threonine producing strains on the basis of a strain with a minimized genome (see below); however, the effect of its inactivation was not assessed [63]. In addi tion, the transport of threonine into a cell is also per formed by the LIV I system of transport of branched amino acids, which is encoded by the livJ and livKH MGF genes [171,172], and at least one other uniden tified transporter [173].…”

Section: Threonine Transport Into a Cellmentioning

confidence: 99%

Directed modification of Escherichia coli metabolism for the design of threonine-producing strains

Yuzbashev

Vybornaya

Larina

et al. 2013

Appl Biochem Microbiol

View full text Add to dashboard Cite

The modification of Escherichia coli K 12 metabolism leading to threonine overproduction is the most studied system in synthetic biology that has been used to elaborate the majority of the currently known approaches to constructing microbial producers. They include optimization of biosynthesis through search for rate limiting stages, modification of substrate and product transport, elimination of side metabolic path ways and degradation systems, reinforcement of the regeneration of coenzymes that are required for product biosynthesis, and exclusion of futile cycles and metabolic pathways with low energy efficiency. Extensive research in functional genomics made it possible to selectively remove the "unnecessary genes," the functions of which are useless for producing a strain or adversely affect its properties. In total, using various approaches to designing threonine producing strains, over 150 genome loci that affect more than 30% genes in E. coli were directly modified, thus providing interesting data for researchers in the field of microbial synthesis, as well as in related biological sciences. This review is dedicated to the assessment of genetic engineering mod ifications in E. coli metabolism (primarily, on the basis of modern patent literature) that ensure threonine overproduction.

show abstract

Amino Acid Transport in Bacteria

Cited by 17 publications

References 177 publications

Lrp, a leucine-responsive protein, regulates branched-chain amino acid transport genes in Escherichia coli

Lrp, a leucine-responsive protein, regulates branched-chain amino acid transport genes in Escherichia coli

Synthesis and thermal behavior of thermotropic terpolymers based on 8‐(3‐hydroxyphenyl)octanoic acid, 2,6‐naphthalenedicarboxylic acid, and substituted hydroquinones

Directed modification of Escherichia coli metabolism for the design of threonine-producing strains

Contact Info

Product

Resources

About