title: Biotransformation of crotonobetaine to L(-)-carnitine in Proteus sp.
abstract: Two proteins, component I (CI) and component II (CII), catalyze the biotransformation of crotonobetaine to L(-)-carnitine in Proteus sp. CI was purified to electrophoretic homogeneity from cell-free extracts of Proteus sp. The N-terminal amino acid sequence of CI showed high similarity (80%) to the caiB gene product from Escherichia coli O44K74, which encodes the L(-)-carnitine dehydratase. CI alone was unable to convert crotonobetaine into L(-)-carnitine even in the presence of the cosubstrates crotonobetainyl-CoA or gamma-butyrobetainyl-CoA, which are essential for this biotransformation. The relative molecular mass of CI was determined to be 91.1 kDa. CI is composed of two identical subunits of molecular mass 43.6 kDa. The isoelectric point is 5.0. CII was purified to electrophoretic homogeneity from cell-free extracts of Proteus sp. and its N-terminal amino acid sequence showed high similarity (75%) to the caiD gene product of E. coli O44K74. The relative molecular mass of CII was shown to be 88.0 kDa, and CII is composed of three identical subunits of molecular mass 30.1 kDa. The isoelectric point of CII is 4.9. For the biotransformation of crotonobetaine to L(-)-carnitine, the presence of CI, CII, and a cosubstrate (crotonobetainyl-CoA or gamma-butyrobetainyl-CoA) were shown to be essential.
authors.affiliation: Institut für Biochemie, Fakultät für Biowissenschaften, Pharmazie und Psychologie, Universität Leipzig, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Engemann
authors.forename: T
authors.initials: T
authors.lastname: Elssner
authors.forename: H P
authors.initials: HP
authors.lastname: Kleber
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000217:Acyltransferases / Q000737:chemistry; D000595:Amino Acid Sequence; D001622:Betaine / Q000031:analogs & derivatives* / Q000378:metabolism*; D001711:Biotransformation; D002331:Carnitine / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006836:Hydro-Lyases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D021122:Protein Subunits; D011511:Proteus / Q000201:enzymology / Q000378:metabolism*; D019998:Racemases and Epimerases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid
chemical_list: D000214:Acyl Coenzyme A; D029968:Escherichia coli Proteins; D021122:Protein Subunits; C413607:crotonobetainyl-CoA; C413606:gamma-butyrobetainyl-CoA; D001622:Betaine; C025237:crotonic acid betaine; D000217:Acyltransferases; C060278:crotonobetainyl-CoA carnitine coenzyme A transferase; D006836:Hydro-Lyases; D019998:Racemases and Epimerases; C091404:caiD protein, E coli; D002331:Carnitine