| Structural highlights
Function
HPBD_PARDP Catalyzes the 2-epimerization of trans-4-hydroxy-L-proline betaine (tHyp-B) to cis-4-hydroxy-D-proline betaine (cHyp-B). Is involved in a catabolic pathway that degrades tHyp-B to alpha-ketoglutarate. This pathway would permit the utilization of tHyp-B as a carbon and nitrogen source in the absence of osmotic stress, since tHyp-B functions as an osmolyte and is not catabolized when it is needed as osmoprotectant. Can also catalyze the racemization of L-proline betaine.[1]
Publication Abstract from PubMed
UNLABELLED: Through the use of genetic, enzymatic, metabolomic, and structural analyses, we have discovered the catabolic pathway for proline betaine, an osmoprotectant, in Paracoccus denitrificans and Rhodobacter sphaeroides. Genetic and enzymatic analyses showed that several of the key enzymes of the hydroxyproline betaine degradation pathway also function in proline betaine degradation. Metabolomic analyses detected each of the metabolic intermediates of the pathway. The proline betaine catabolic pathway was repressed by osmotic stress and cold stress, and a regulatory transcription factor was identified. We also report crystal structure complexes of the P. denitrificans HpbD hydroxyproline betaine epimerase/proline betaine racemase with l-proline betaine and cis-hydroxyproline betaine. IMPORTANCE: At least half of the extant protein annotations are incorrect, and the errors propagate as the number of genome sequences increases exponentially. A large-scale, multidisciplinary sequence- and structure-based strategy for functional assignment of bacterial enzymes of unknown function has demonstrated the pathway for catabolism of the osmoprotectant proline betaine.
Prediction and biochemical demonstration of a catabolic pathway for the osmoprotectant proline betaine.,Kumar R, Zhao S, Vetting MW, Wood BM, Sakai A, Cho K, Solbiati J, Almo SC, Sweedler JV, Jacobson MP, Gerlt JA, Cronan JE MBio. 2014 Feb 11;5(1):e00933-13. doi: 10.1128/mBio.00933-13. PMID:24520058[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Zhao S, Kumar R, Sakai A, Vetting MW, Wood BM, Brown S, Bonanno JB, Hillerich BS, Seidel RD, Babbitt PC, Almo SC, Sweedler JV, Gerlt JA, Cronan JE, Jacobson MP. Discovery of new enzymes and metabolic pathways by using structure and genome context. Nature. 2013 Sep 22. doi: 10.1038/nature12576. PMID:24056934 doi:http://dx.doi.org/10.1038/nature12576
- ↑ Kumar R, Zhao S, Vetting MW, Wood BM, Sakai A, Cho K, Solbiati J, Almo SC, Sweedler JV, Jacobson MP, Gerlt JA, Cronan JE. Prediction and biochemical demonstration of a catabolic pathway for the osmoprotectant proline betaine. MBio. 2014 Feb 11;5(1):e00933-13. doi: 10.1128/mBio.00933-13. PMID:24520058 doi:http://dx.doi.org/10.1128/mBio.00933-13
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