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dc.contributor.authorPeña-Soler, Esther-
dc.contributor.authorFernández, Francisco J.-
dc.contributor.authorLópez-Estepa, Miguel-
dc.contributor.authorGarces, Fernando-
dc.contributor.authorRichardson, Andrew J.-
dc.contributor.authorQuintana, Juan F.-
dc.contributor.authorRudd, Kenneth E.-
dc.contributor.authorColl, Miquel-
dc.contributor.authorVega, María Cristina-
dc.identifier.citationPLoS ONE 9 (7): e102139.es_ES
dc.description15 p.-2 tab.-8 fig.es_ES
dc.description.abstractIn order to maintain proper cellular function, the metabolism of the bacterial microbiota presents several mechanisms oriented to keep a correctly balanced amino acid pool. Central components of these mechanisms are enzymes with alanine transaminase activity, pyridoxal 59-phosphate-dependent enzymes that interconvert alanine and pyruvate, thereby allowing the precise control of alanine and glutamate concentrations, two of the most abundant amino acids in the cellular amino acid pool. Here we report the 2.11-A° crystal structure of full-length AlaA from the model organism Escherichia coli, a major bacterial alanine aminotransferase, and compare its overall structure and active site composition with detailed atomic models of two other bacterial enzymes capable of catalyzing this reaction in vivo, AlaC and valine-pyruvate aminotransferase (AvtA). Apart from a narrow entry channel to the active site, a feature of this new crystal structure is the role of an active site loop that closes in upon binding of substrate-mimicking molecules, and which has only been previously reported in a plant enzyme. Comparison of the available structures indicates that beyond superficial differences, alanine aminotransferases of diverse phylogenetic origins share a universal reaction mechanism that depends on an array of highly conserved amino acid residues and is similarly regulated by various unrelated motifs. Despite this unifying mechanism and regulation, growth competition experiments demonstrate that AlaA, AlaC and AvtA are not freely exchangeable in vivo, suggesting that their functional repertoire is not completely redundant thus providing an explanation for their independent evolutionary conservation.es_ES
dc.description.sponsorshipThis work was supported by the Spanish Ministry of Economy and Competitiveness (grants PET2008_0101, BIO2009-11184 and BFU2010-22260-C02-02 to MCV and BFU2008-02372/BMC, CSD 2006-23 and BFU2011-22588 to MC), the Generalitat de Catalunya (grant SGR2009-1309 to MC), the European Commission (Framework Programme 7 (FP7) projects ComplexINC No. 279039 to MCV), and the US National Institutes of Health (grant 1-R01-GM58560 to KER and AJR).es_ES
dc.publisherPublic Library of Sciencees_ES
dc.relation.isversionofPublisher's versiones_ES
dc.titleStructural analysis and mutant growth properties reveal distinctive enzymatic and cellular roles for the three major L-alanine transaminases of Escherichia colies_ES
dc.description.peerreviewedPeer reviewedes_ES
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