MetaCyc Enzyme: pyridoxine 4-oxidase

Gene: pno Accession Number: G-10000 (MetaCyc)

Synonyms: mll6785

Species: Mesorhizobium loti

Sequence analysis has shown that the pno gene of Mesorhizobium loti is similar to genes encoding pyridoxine 4-oxidase in other organisms. The gene was cloned and expressed in Escherichia coli, and found to encode an active monomeric pyridoxine 4-oxidase. This led to the finding that Mesorhizobium loti posseses a degradation pathway for pyridoxamine and pyridoxine, and is able to utilize these compounds as sole carbon and nitrogen sources.

Enzymatic activity was also measured in crude extracts of Mesorhizobium loti grown on Rhizobium medium supplemented with pyridoxine (0.63 mU/mg), demonstrating that the enzyme is expressed in its native host [Yuan04].

The cloned gene was later expressed in E. coli as a His-tagged protein, and purified to homogeneity. The purified enzyme was crystallized [Mugo12].

Gene Citations: [Kaneko00]

Molecular Weight of Polypeptide: 55.712 kD (from nucleotide sequence), 54.5 kD (experimental) [Yuan04 ]

Unification Links: Entrez-gene:1229883 , Protein Model Portal:Q988D6 , String:266835.mll6785 , UniProt:Q988D6

Relationship Links: Entrez-Nucleotide:RELATED-TO:BA000012 , InterPro:IN-FAMILY:IPR000172 , InterPro:IN-FAMILY:IPR007867 , InterPro:IN-FAMILY:IPR012132 , Pfam:IN-FAMILY:PF00732 , Pfam:IN-FAMILY:PF05199 , Prosite:IN-FAMILY:PS00623 , Prosite:IN-FAMILY:PS00624

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Created 05-Apr-2007 by Caspi R , SRI International

Enzymatic reaction of: pyridoxine 4-oxidase

EC Number:

pyridoxine + oxygen <=> hydrogen peroxide + pyridoxal

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: vitamin B6 degradation

Cofactors or Prosthetic Groups: FAD [Yuan04]

Kinetic Parameters:

Km (μM)

T(opt): 40 °C [Yuan04]

pH(opt): 8-8.5 [Yuan04]


Kaneko00: Kaneko T, Nakamura Y, Sato S, Asamizu E, Kato T, Sasamoto S, Watanabe A, Idesawa K, Ishikawa A, Kawashima K, Kimura T, Kishida Y, Kiyokawa C, Kohara M, Matsumoto M, Matsuno A, Mochizuki Y, Nakayama S, Nakazaki N, Shimpo S, Sugimoto M, Takeuchi C, Yamada M, Tabata S (2000). "Complete genome structure of the nitrogen-fixing symbiotic bacterium Mesorhizobium loti." DNA Res 7(6);331-8. PMID: 11214968

Mugo12: Mugo AN, Kobayashi J, Mikami B, Ohnishi K, Yagi T (2012). "Crystallization and preliminary X-ray analysis of pyridoxine 4-oxidase, the first enzyme in pyridoxine degradation pathway I." Acta Crystallogr Sect F Struct Biol Cryst Commun 68(Pt 1);66-8. PMID: 22232175

Yuan04: Yuan B, Yoshikane Y, Yokochi N, Ohnishi K, Yagi T (2004). "The nitrogen-fixing symbiotic bacterium Mesorhizobium loti has and expresses the gene encoding pyridoxine 4-oxidase involved in the degradation of vitamin B6." FEMS Microbiol Lett 234(2);225-30. PMID: 15135526

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Mon Oct 5, 2015, BIOCYC14B.