scholarly journals Analysis of the LIV System of Campylobacter jejuni Reveals Alternative Roles for LivJ and LivK in Commensalism beyond Branched-Chain Amino Acid Transport

2011 ◽  
Vol 193 (22) ◽  
pp. 6233-6243 ◽  
Author(s):  
Deborah A. Ribardo ◽  
David R. Hendrixson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Campylobacter Jejuni ◽  
Transport System ◽  
Amino Acid Transport ◽  
Branched Chain Amino Acids ◽  
Acid Transport ◽  
Content Type ◽  
Branched Chain Amino Acid ◽  
Branched Chain

Campylobacter jejuniis a leading cause of diarrheal disease in humans and an intestinal commensal in poultry and other agriculturally important animals. These zoonotic infections result in significant amounts ofC. jejunipresent in the food supply to contribute to disease in humans. We previously found that a transposon insertion inCjj81176_1038, encoding a homolog of theEscherichia coliLivJ periplasmic binding protein of the leucine, isoleucine, and valine (LIV) branched-chain amino acid transport system, reduced the commensal colonization capacity ofC. jejuni81-176 in chicks.Cjj81176_1038is the first gene of a six-gene locus that encodes homologous components of theE. coliLIV system. By analyzing mutants with in-frame deletions of individual genes or pairs of genes, we found that this system constitutes a LIV transport system inC. jejuniresponsible for a high level of leucine acquisition and, to a lesser extent, isoleucine and valine acquisition. Despite each LIV protein being required for branched-chain amino acid transport, only the LivJ and LivK periplasmic binding proteins were required for wild-type levels of commensal colonization of chicks. All LIV permease and ATPase components were dispensable forin vivogrowth. These results suggest that the biological functions of LivJ and LivK for colonization are more complex than previously hypothesized and extend beyond a role for binding and acquiring branched-chain amino acids during commensalism. In contrast to other studies indicating a requirement and utilization of other specific amino acids for colonization, acquisition of branched-chain amino acids does not appear to be a determinant forC. jejuniduring commensalism.

scholarly journals Role of Branched-Chain Amino Acid Transport in Bacillus subtilis CodY Activity

2015 ◽  
Vol 197 (8) ◽  
pp. 1330-1338 ◽  
Author(s):  
Boris R. Belitsky
Keyword(s):  
Amino Acids ◽  
Bacillus Subtilis ◽  
Amino Acid ◽  
Growth Medium ◽  
Amino Acid Transport ◽  
Transcriptional Regulator ◽  
Acid Transport ◽  
Content Type ◽  
Branched Chain Amino Acid ◽  
Branched Chain

ABSTRACTCodY is a branched-chain amino acid-responsive transcriptional regulator that controls the expression of several dozen transcription units inBacillus subtilis. The presence of isoleucine, valine, and leucine in the growth medium is essential for achieving high activity of CodY and for efficient regulation of the target genes. We identified three permeases—BcaP, BraB, and BrnQ—that are responsible for the bulk of isoleucine and valine uptake and are also involved in leucine uptake. At least one more permease is capable of efficient leucine uptake, as well as low-affinity transport of isoleucine and valine. The lack of the first three permeases strongly reduced activity of CodY in an amino acid-containing growth medium. BcaP appears to be the most efficient isoleucine and valine permease responsible for their utilization as nitrogen sources. The previously described strong CodY-mediated repression of BcaP provides a mechanism for fine-tuning CodY activity by reducing the availability of amino acids and for delaying the utilization of isoleucine and valine as nitrogen and carbon sources under conditions of nutrient excess.IMPORTANCEBacillus subtilisCodY is a global transcriptional regulator that is activated by branched-chain amino acids (BCAA). Since the level of BCAA achieved by intracellular synthesis is insufficient to fully activate CodY, transport of BCAA from the environment is critical for CodY activation, but the permeases needed for such activation have not been previously identified. This study identifies three such permeases, reports their amino acid transport specificity, and reveals their impact on CodY activation.

Lipid requirement of the branched-chain amino acid transport system of Streptococcus cremoris

Biochemistry ◽  
1988 ◽  
Vol 27 (3) ◽  
pp. 865-872 ◽  
Author(s):  
Arnold J. M. Driessen ◽  
Tan Zheng ◽  
Gerda In't Veld ◽  
Jos A. F. Op den Kamp ◽  
Wil N. Konings
Keyword(s):  
Amino Acid ◽  
Transport System ◽  
Amino Acid Transport ◽  
Acid Transport ◽  
Amino Acid Transport System ◽  
Branched Chain Amino Acid ◽  
Streptococcus Cremoris ◽  
Branched Chain ◽  
Lipid Requirement

scholarly journals Identification and Functional Characterization of the Lactococcus lactis CodY-Regulated Branched-Chain Amino Acid Permease BcaP (CtrA)

2006 ◽  
Vol 188 (9) ◽  
pp. 3280-3289 ◽  
Author(s):  
Chris D. den Hengst ◽  
Maarten Groeneveld ◽  
Oscar P. Kuipers ◽  
Jan Kok
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Lactococcus Lactis ◽  
Amino Acid Transport ◽  
Amino Acid Transporter ◽  
Acid Transport ◽  
Amino Acid Permease ◽  
Branched Chain Amino Acid ◽  
Acid Transporter ◽  
Branched Chain

ABSTRACT Transcriptome analyses have previously revealed that a gene encoding the putative amino acid transporter CtrA (YhdG) is one of the major targets of the pleiotropic regulator CodY in Lactococcus lactis and Bacillus subtilis. The role of ctrA in L. lactis was further investigated with respect to both transport activity as well as CodY-mediated regulation. CtrA is required for optimal growth in media containing free amino acids as the only amino acid source. Amino acid transport studies showed that ctrA encodes a secondary amino acid transport system that is specific for branched-chain amino acids (BCAAs) (isoleucine, leucine, and valine) and methionine, which is in disagreement with its previously proposed function (a cationic amino acid transporter), which was assigned based on homology. We propose to rename CtrA BcaP, for branched-chain amino acid permease. BcaP is a member of a group of conserved transport systems, as homologs are widely distributed among gram-positive bacteria. Deletion of bcaP resulted in the loss of most of the BCAA uptake activity of L. lactis, indicating that BcaP is the major BCAA carrier of this organism. Deletion of bcaP together with a second (putative) BCAA permease, encoded by brnQ, further reduced the viability of the strain. DNA microarray analysis showed that deletion of bcaP predominantly affects genes belonging to the regulons of the transcriptional regulator CodY, which is involved in global nitrogen metabolism and needs BCAAs for its activation, and of CmbR, which is involved in sulfur amino acid metabolism.

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