Location of livA gene participating in the high-affinity transport of branched-chain amino acids in Salmonella typhimurium lt2.

Matsubara, Keiko; Ohnishi, Kouhei; Kiritani, Kazuyoshi

doi:10.1266/jjg.62.189

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…One explanation for these results is that the proZ mutations may activate a cryptic proline transport system (13). However, since isoleucine and leucine competitively inhibit proline transport by proZ mutants (Table 6), the ProZ phenotype may be due to a novel substrate specificity mutation in the branched-chain amino acid transport system encoded by the liv genes (17). We plan to test this prediction by fine-structure genetic mapping of proZ mutations versus liv mutations.…”

Section: Resultsmentioning

confidence: 99%

Activation of a new proline transport system in Salmonella typhimurium

1990

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Proline uptake can be mediated by three different transport systems in wild-type Salmonella typhimurium: a high-affinity proline transport system encoded by the putP gene and two glycine-betaine transport systems with a low affinity for proline encoded by the proP and proU genes. However, only the PutP permease transports proline well enough t allow growth on proline as a sole carbon or nitrogen source. By selecting for mutations that allow a putP mutant to grow on proline as a sole nitrogen source, we isolated mutants (designated proZ) that appeared to activate a cryptic proline transport system. These mutants enhanced the transport of proline and proline analogs but did not require the function of any of the known proline transport genes. The mutations mapped between 75 and 77.5 min on the S. typhimurium linkage map. Proline transport by the proZ mutants was competitively inhibited by isoleucine and leucine, which suggests that the ProZ phenotype may be due to unusual mutations that alter the substrate specificity of the branched-chain amino acid transport system encoded by the liv genes.

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Section: Resultsmentioning

confidence: 99%

Activation of a new proline transport system in Salmonella typhimurium

1990

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“…Clones that complement the branched-chain amino acid transport defect were isolated from a random library of S. typhimurium chromosomal DNA cloned into pBR328. Plasmids from this library were introduced into KA261 by selecting for Amp r transformants, and the resulting colonies were screened for growth on minimal glucose plates supplemented with glycyl-valine and isoleucine (Matsubara et al ., 1987).…”

Section: Resultsmentioning

confidence: 99%

“…W e previously isolated mutants in a gene designated proZ which suppress this phenotype, allowing putP mutants to grow o n proline as sole nitrogen source (Ekena et al, 1990). To further characterize the proZ mutant, we wanted to clone the and proY in the BamHI site of pBR328 Matsubara et al (1987) Myers et al (1991 Laboratory collection Ekena et al (1990) 1985Stratagene Covarrubias et al (1981Covarrubias et al (1981Mead et al (1986…”

Section: Multicopy Suppression Of Putpmentioning

confidence: 99%

A cryptic proline permease in Salmonella typhimurium

1997

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Wild-type Salmonella typhimurium expresses three proline transport systems : a high-affinity proline transport system encoded by the putP gene, and two glycine betaine transport systems with a lower affinity for proline encoded by the prop and proU genes. Although proline uptake by the Prop and ProU transport systems is sufficient to supplement a proline auxotroph, it is not efficient enough to allow proline utilization as a sole source of carbon or nitrogen. Thus, the PutP transport system is required for utilization of proline as a carbon or nitrogen source. In this study, an overexpression suppressor, designated pmY, which allows proline utilization in a putP genetic background and does not require the function of any of the known proline transport systems, was cloned and characterized. The suppressor gene, designated proY, maps at 8 min on the 5. typhimurium linkage map, distant from any of the other characterized proline transport genes. The DNA sequence of the proY gene predicts that it encodes a hydrophobic integral membrane protein, with strong similarity to a family of amino acid transporters. The suppressor phenotype requires either a multicopy clone of the pmY+ gene or both a single copy of the p r o p gene and a pmZ mutation. These results indicate that the proY gene is the structural gene for a cryptic proline transporter that is silent unless overexpressed on a multicopy plasmid or activated by a proZ mutation.

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“…The LIV-I system contains a periplasmic binding protein binding to leucine, isoleucine, valine, and threonine (Ohnishi and Kiritani, 1983). A structural gene, livA, controlling the LIV-I system is located at 76-77 min on the Salmonella genetic map (Matsubara et al, 1987). The LIV-II system appears to be the major transport system as judged by kinetic and genetic analyses (Matsubara et al, 1988), and is governed by the brnQ gene, located at 8 min on the map (Kiritani, 1974;Sanderson and Roth, 1983).…”

Section: Introductionmentioning

confidence: 99%