Proline dehydrogenase from Thermus thermophilus does not discriminate between FAD and FMN as cofactor

Huijbers, M. M. E. ; Martínez-Júlvez, M. (Universidad de Zaragoza) ; Westphal, A. H. ; Delgado-Arciniega, E. ; Medina, M. (Universidad de Zaragoza) ; Van Berkel, W. J. H.

Resumen: Flavoenzymes are versatile biocatalysts containing either FAD or FMN as cofactor. FAD often binds to a Rossmann fold, while FMN prefers a TIM-barrel or flavodoxin-like fold. Proline dehydrogenase is denoted as an exception: it possesses a TIM barrel-like fold while binding FAD. Using a riboflavin auxotrophic Escherichia coli strain and maltose-binding protein as solubility tag, we produced the apoprotein of Thermus thermophilus ProDH (MBP-TtProDH). Remarkably, reconstitution with FAD or FMN revealed that MBP-TtProDH has no preference for either of the two prosthetic groups. Kinetic parameters of both holo forms are similar, as are the dissociation constants for FAD and FMN release. Furthermore, we show that the holo form of MBP-TtProDH, as produced in E. coli TOP10 cells, contains about three times more FMN than FAD. In line with this flavin content, the crystal structure of TtProDH variant ¿ABC, which lacks helices aA, aB and aC, shows no electron density for an AMP moiety of the cofactor. To the best of our knowledge, this is the first example of a flavoenzyme that does not discriminate between FAD and FMN as cofactor. Therefore, classification of TtProDH as an FAD-binding enzyme should be reconsidered.

Idioma: Inglés

DOI: 10.1038/srep43880

Año: 2017

Publicado en: Scientific reports 7 (2017), 43880 [13 pp.]
ISSN: 2045-2322

Factor impacto JCR: 4.122 (2017)

Categ. JCR: MULTIDISCIPLINARY SCIENCES rank: 12 / 64 = 0.188 (2017) - Q1 - T1

Factor impacto SCIMAGO: 1.533 - Multidisciplinary (Q1)

Financiación: info:eu-repo/grantAgreement/ES/MICINN/BIO2013-42978-P

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Bioquímica y Biolog.Mole. (Dpto. Bioq.Biolog.Mol. Celular)