l-Hydroxyproline andd-Proline Catabolism in Sinorhizobium meliloti

Abstract

Sinorhizobium meliloti IMPORTANCEHydroxyproline is abundant in proteins in animal and plant tissues and serves as a carbon and a nitrogen source for bacteria in diverse environments, including the rhizosphere, compost, and the mammalian gut. While the main biochemical features of bacterial hydroxyproline catabolism were elucidated in the 1960s, the genetic and molecular details have only recently been determined. Elucidating the genetics of hydroxyproline catabolism will aid in the annotation of these genes in other genomes and metagenomic libraries. This will facilitate an improved understanding of the importance of this pathway and may assist in determining the prevalence of hydroxyproline in a particular environment.4-Hydroxyproline and 3-hydroxyproline in animal and plant proteins are formed through the posttranslational modification of proline residues by the enzyme proline hydroxylase. In some bacteria, hydroxyproline is synthesized from free L-proline, where it is employed in the synthesis of secondary metabolites (1, 2). 4-Hydroxyproline has two chiral carbon atoms, and of its four isomeric forms, trans-4-hydroxy-L-proline (trans-4-L-Hyp) and cis-4-hydroxy-D-proline (cis-4-D-Hyp) appear to be the two most common isomers. trans-4-

Characterization of a Novel cis -3-Hydroxy- l -Proline Dehydratase and a trans -3-Hydroxy- l -Proline Dehydratase from Bacteria

“…On the other hand, the L-Hyp gene clusters of L. aggregata IAM 12614 (possibly also S. novella DSM 506) and Sinorhizobium meliloti 2011 consist of genes for T4LHyp, T3LHyp, and C3LHyp metabolism (Fig. 2D), and the L-Hyp gene cluster of L. aggregata IAM 12614 is induced by all of these L-Hyp proteins; however, they metabolize 3-hydroxy-L-prolines very poorly (13,14,18,24). Furthermore, the functional characterization of the AcnX, HypA1, and HypA2 proteins from M. viridifaciens indicated that the L-Hyp gene cluster is additionally involved in the metabolism of C3DHyp (Fig.…”

“…The catabolism of L-Hyp, including T4LHyp, T3LHyp, and C3LHyp, by (micro)organisms has recently been investigated at the molecular level ( Fig. 2A to C and Table 1; see also Table S1 in the supplemental material) (12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”

“…This finding strongly suggests that the T4LHyp pathway evolved convergently in bacteria. Finally, HPC is converted to ␣-ketoglutarate via ␣-ketoglutaric semialdehyde (KGSA) by HPC deaminase and KGSA dehydrogenase, encoded by the hypE and hypF genes, respectively (15,17,18). In the metabolism of T3LHyp (Fig.…”

Molecular characterization of LhpR in control of hydroxyproline catabolism and transport in Pseudomonas aeruginosa PAO1

“…Third, the purified recombinant LhpR protein binds specifically to the DNA fragments covering the lhpA regulatory region. The situation in P. aeruginosa appears to be quite different from that of S. meliloti, in which L-Hyp catabolism is regulated in a negative manner by a transcriptional regulator of the GntR (FadR) family in response to the presence of D-Hyp and D-Pro as the inducer molecule (Chen et al, 2016;White et al, 2012).…”

Anaerobic 4-hydroxyproline utilization: Discovery of a new glycyl radical enzyme in the human gut microbiome uncovers a widespread microbial metabolic activity

“…24 The enzymes from this pathway have been characterized in Pseudomonas and Sinorhizobium . 20 , 25 Aerobic Hyp metabolism involves sequential oxidations of Hyp to generate α-ketoglutarate (α-KG) and ammonia, providing carbon and nitrogen for anabolic pathways (Fig. 2D).…”