The novel transmembrane <i>Escherichia coli</i> proteins involved in the amino acid efflux

Zakataeva, Natalia P.; Aleshin, Vladimir V.; Tokmakova, Irina L.; Troshin, Petr V.; Livshits, Vitaliy A.

doi:10.1016/s0014-5793(99)00625-0

Cited by 104 publications

(72 citation statements)

References 34 publications

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“…1C), suggesting that M and T could provide additional cooperative benefit to one another specifically for this pairing. Furthermore, the presence of characterized exporters for L-methionine and L-threonine could further facilitate syntrophy in this subgroup (26).The synergistic effect of branched pathway shunt is also seen for the M-I, K-I, K-T, and G-C pairs, although to a lesser extent. Lower synergism in these pairs may be due to increasing numbers of intermediates and potential for branch down-regulation as previously suggested (14).…”

Section: Resultsmentioning

confidence: 91%

“…Such membrane transport systems have been recently characterized and many more are being found with the help of metagenomic sequencing. Our E. coli genome encodes several amino acid exporters for excretion of different amino acids including L-threonine (RhtA and RhtC) (26), L-leucine (YeaS) (29), L-aromatic amino acids (YddG) (30), L-arginine (YggA) (31), L-alanine (alaE) (32), and L-homoserine (RhtB) (26). Other exporters have been documented in related organisms including lysE for L-lysine export and brnFE for L-isoleucine and L-methionine export in Corynebacterium glutamicum (33,34).…”

Section: Discussionmentioning

confidence: 99%

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Syntrophic exchange in synthetic microbial communities

Mee

Collins

Church

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

505

526

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Metabolic crossfeeding is an important process that can broadly shape microbial communities. However, little is known about specific crossfeeding principles that drive the formation and maintenance of individuals within a mixed population. Here, we devised a series of synthetic syntrophic communities to probe the complex interactions underlying metabolic exchange of amino acids. We experimentally analyzed multimember, multidimensional communities of Escherichia coli of increasing sophistication to assess the outcomes of synergistic crossfeeding. We find that biosynthetically costly amino acids including methionine, lysine, isoleucine, arginine, and aromatics, tend to promote stronger cooperative interactions than amino acids that are cheaper to produce. Furthermore, cells that share common intermediates along branching pathways yielded more synergistic growth, but exhibited many instances of both positive and negative epistasis when these interactions scaled to higher dimensions. In more complex communities, we find certain members exhibiting keystone species-like behavior that drastically impact the community dynamics. Based on comparative genomic analysis of >6,000 sequenced bacteria from diverse environments, we present evidence suggesting that amino acid biosynthesis has been broadly optimized to reduce individual metabolic burden in favor of enhanced crossfeeding to support synergistic growth across the biosphere. These results improve our basic understanding of microbial syntrophy while also highlighting the utility and limitations of current modeling approaches to describe the dynamic complexities underlying microbial ecosystems. This work sets the foundation for future endeavors to resolve key questions in microbial ecology and evolution, and presents a platform to develop better and more robust engineered synthetic communities for industrial biotechnology.synthetic ecosystem | amino acid exchange | population modeling M icrobes are abundantly found in almost every part of the world, living in communities that are diverse in many facets. Although it is clear that cooperation and competition within microbial communities is central to their stability, maintenance, and longevity, there is limited knowledge about the general principles guiding the formation of these intricate systems. Understanding the underlying governing principles that shape a microbial community is key for microbial ecology but is also crucial for engineering synthetic microbiomes for various biotechnological applications (1-3). Numerous such examples have been recently described including the bioconversion of unprocessed cellulolytic feedstocks into biofuel isobutanol using fungal-bacterial communities (4) and biofuel precursor methyl halides using yeast-bacterial cocultures (5). Other emerging applications in biosensing and bioremediation against environmental toxins such as arsenic (6) and pathogens such as Pseudomonas aeruginosa and Vibrio cholerae have been demonstrated using engineered quorum-sensing Escherichia coli (7, 8). These ...

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Section: Resultsmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Syntrophic exchange in synthetic microbial communities

Mee

Collins

Church

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

505

526

View full text Add to dashboard Cite

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“…For example, Escherichia coli encodes multiple proteins for the export of sugars, such as glucose and lactose (1), and for arabinose (2,3). In addition, the occurrence of proteins mediating export of amino acids, such as alanine (4), arginine (5), aromatic amino acids (6), cysteine (7,8), leucine (9), threonine (10,11) and valine (12), in E. coli has been reported. While the physiological basis for the existence of amino acid exporters is not clear, their occurrence is relatively widespread in bacteria (13,14).…”

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confidence: 99%

Distinct Paths for Basic Amino Acid Export in Escherichia coli: YbjE (LysO) Mediates Export of l -Lysine

Pathania

Sardesai

2015

J Bacteriol

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In Escherichia coli, argO encodes an exporter for L-arginine (Arg) and its toxic analogue canavanine (CAN), and its transcriptional activation and repression, by Arg and L-lysine (Lys), respectively, are mediated by the regulator ArgP. Accordingly argO and argP mutants are CAN supersensitive (CAN ss IMPORTANCEThis work ascribes a lysine export function to the product of the ybjE gene of Escherichia coli, leading to a physiological scenario wherein two proteins, ArgO and YbjE, perform the task of separately exporting arginine and lysine, respectively, which is distinct from that seen for Corynebacterium glutamicum, where the ortholog of ArgO, LysE, mediates export of both arginine and lysine. Repression of argO transcription by lysine is thought to effect this separation. Accordingly, ArgO mediates lysine export when repression of its transcription by lysine is bypassed. Repression of ybjE transcription by arginine via the ArgR repressor, together with the lysine repression of argO effected by ArgP, is indicative of a mechanism of maintenance of arginine/lysine balance in E. coli. Bacteria possess membrane exporters for a variety of compounds. Their activities to a large extent are thought to play an adaptive role in mitigating the detrimental effects on bacterial growth caused by the presence of biotic stresses, such as those imposed by antibiotics, heavy metals, and other toxic compounds, in their natural environments. While it is easy to come to terms with the existence of proteins that mediate export of compounds described above, the presence of specific export systems for cellular metabolites such as sugars and amino acids appears somewhat enigmatic. For example, Escherichia coli encodes multiple proteins for the export of sugars, such as glucose and lactose (1), and for arabinose (2, 3). In addition, the occurrence of proteins mediating export of amino acids, such as alanine (4), arginine (5), aromatic amino acids (6), cysteine (7, 8), leucine (9), threonine (10, 11) and valine (12), in E. coli has been reported. While the physiological basis for the existence of amino acid exporters is not clear, their occurrence is relatively widespread in bacteria (13,14). It is thought that an amino acid exporter may serve to contribute to the fitness of an organism during conditions of metabolic imbalance resulting from excessive levels of its amino acid substrate in the cytoplasm (13,14). An alternative view could be that export of the amino acid occurs by chance, with the cognate substrate being a naturally occurring structurally related antimetabolite present in the environment. As an example of the latter, one mechanism contributing to the resistance of E. coli to the plant-derived antimetabolite canavanine (CAN), an L-arginine analogue, involves its export by ArgO, the ortholog of the basic amino acid exporter LysE of Corynebacterium glutamicum, following its uptake (5). Harnessing the amino acid export potential of a given bacterium has found widespread application in the commercial production of amin...

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“…However, an Arg efflux system is not known to exist in E. coli, and indeed only a few amino acid exporters have been characterized for any bacterium (reviewed in references 1, 9, and 17). The amino acid exporters so far identified for E. coli include RhtB and RhtC, for threonine and homoserine (27,43), and YdeD and YfiK, for cysteine and O-acetylserine (16,18). The exporter LysE, for both Lys and Arg, has been well characterized in Corynebacterium glutamicum, and the primary sequence of LysE is similar to the product of an E. coli open reading frame called yggA (3,7,8,42).…”

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confidence: 99%

Evidence for an Arginine Exporter Encoded by yggA ( argO ) That Is Regulated by the LysR-Type Transcriptional Regulator ArgP in Escherichia coli

2004

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The anonymous open reading frame yggA of Escherichia coli was identified in this study as a gene that is under the transcriptional control of argP (previously called iciA), which encodes a LysR-type transcriptional regulator protein. Strains with null mutations in either yggA or argP were supersensitive to the arginine analog canavanine, and yggA-lac expression in vivo exhibited argP ؉ -dependent induction by arginine. Lysine supplementation phenocopied the argP null mutation in that it virtually abolished yggA expression, even in the argP ؉ strain. The dipeptides arginylalanine and lysylalanine behaved much like arginine and lysine, respectively, to induce and to turn off yggA transcription. Dominant missense mutations in argP (argP d ) that conferred canavanine resistance and rendered yggA-lac expression constitutive were obtained. The protein deduced to be encoded by yggA shares similarity with a basic amino acid exporter (LysE) of Corynebacterium glutamicum, and we obtained evidence for increased arginine efflux from E. coli strains with either the argP d mutation or multicopy yggA ؉ . The null yggA mutation abolished the increased arginine efflux from the argP d strain. Our results suggest that yggA encodes an ArgP-regulated arginine exporter, and we have accordingly renamed it argO (for "arginine outward transport"). We propose that the physiological function of argO may be either to prevent the accumulation to toxic levels of canavanine (which is a plant-derived antimetabolite) or arginine or to maintain an appropriate balance between the intracellular lysine and arginine concentrations.

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The novel transmembrane Escherichia coli proteins involved in the amino acid efflux

Cited by 104 publications

References 34 publications

Syntrophic exchange in synthetic microbial communities

Syntrophic exchange in synthetic microbial communities

Distinct Paths for Basic Amino Acid Export in Escherichia coli: YbjE (LysO) Mediates Export of l -Lysine

Evidence for an Arginine Exporter Encoded by yggA ( argO ) That Is Regulated by the LysR-Type Transcriptional Regulator ArgP in Escherichia coli

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