1.l-Hydroxyproline and d-Proline Catabolism in Sinorhizobium meliloti.
Chen S1, White CE1, diCenzo GC1, Zhang Y1, Stogios PJ2, Savchenko A2, Finan TM3. J Bacteriol. 2016 Feb 1;198(7):1171-81. doi: 10.1128/JB.00961-15.
Sinorhizobium meliloti forms N2-fixing root nodules on alfalfa, and as a free-living bacterium, it can grow on a very broad range of substrates, including l-proline and several related compounds, such as proline betaine, trans-4-hydroxy-l-proline (trans-4-l-Hyp), and cis-4-hydroxy-d-proline (cis-4-d-Hyp). Fourteen hyp genes are induced upon growth of S. meliloti on trans-4-l-Hyp, and of those, hypMNPQ encodes an ABC-type trans-4-l-Hyp transporter and hypRE encodes an epimerase that converts trans-4-l-Hyp to cis-4-d-Hyp in the bacterial cytoplasm. Here, we present evidence that the HypO, HypD, and HypH proteins catalyze the remaining steps in which cis-4-d-Hyp is converted to α-ketoglutarate. The HypO protein functions as a d-amino acid dehydrogenase, converting cis-4-d-Hyp to Δ(1)-pyrroline-4-hydroxy-2-carboxylate, which is deaminated by HypD to α-ketoglutarate semialdehyde and then converted to α-ketoglutarate by HypH. The crystal structure of HypD revealed it to be a member of the N-acetylneuraminate lyase subfamily of the (α/β)8 protein family and is consistent with the known enzymatic mechanism for other members of the group.
2.Investigation of vitamin B6 inadequacy, induced by exposure to the anti-B6 factor 1-amino D-proline, on plasma lipophilic metabolites of rats: a metabolomics approach.
Mayengbam S1, House JD1,2, Aliani M3,4. Eur J Nutr. 2016 Apr;55(3):1213-23. doi: 10.1007/s00394-015-0934-x. Epub 2015 May 26.
PURPOSE: Vitamin B6 status in the body is affected by several factors including dietary supply of the antivitamin B6 factor, 1-amino D-proline (1ADP), which is present in flaxseed. Owing to the prevalence of moderate B6 deficiency in the general population, a co-occurrence of 1ADP may lead to a further deterioration of B6 status. To this end, we applied a nontargeted metabolomics approach to identify potential plasma lipophilic biomarkers of deleterious effect of 1ADP on moderately vitamin B6-deficient rats using a high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.