4XDR

Crystal structure of Treponema pallidum TP0796 Flavin trafficking protein, a bifunctional FMN transferase/FAD pyrophosphatase, D284A mutant, ADN bound form

Summary for 4XDR

• Entry DOI: 10.2210/pdb4xdr/pdb
• Related: 4IFU
• Descriptor: FAD:protein FMN transferase, MAGNESIUM ION, ADENOSINE, ... (6 entities in total)
• Functional Keywords: fmn transferase, fad pyrophosphatase, hydrolase, bimetal center, flavin turnover, treponema pallidum, transferase
• Biological source: Treponema pallidum (strain Nichols)
• Cellular location: Cell inner membrane ; Lipid-anchor ; Periplasmic side : O83774
• Total number of polymer chains: 1
• Total formula weight: 37655.13

Authors

Tomchick, D.R.,Brautigam, C.A.,Deka, R.K.,Norgard, M.V. (deposition date: 2014-12-19, release date: 2015-10-14, Last modification date: 2023-09-27)

Primary citation

Deka, R.K.,Brautigam, C.A.,Liu, W.Z.,Tomchick, D.R.,Norgard, M.V.
Evidence for Posttranslational Protein Flavinylation in the Syphilis Spirochete Treponema pallidum: Structural and Biochemical Insights from the Catalytic Core of a Periplasmic Flavin-Trafficking Protein.
Mbio, 6:e00519-e00515, 2015

PubMed Abstract: The syphilis spirochete Treponema pallidum is an important human pathogen but a highly enigmatic bacterium that cannot be cultivated in vitro. T. pallidum lacks many biosynthetic pathways and therefore has evolved the capability to exploit host-derived metabolites via its periplasmic lipoprotein repertoire. We recently reported a flavin-trafficking protein in T. pallidum (Ftp_Tp; TP0796) as the first bacterial metal-dependent flavin adenine dinucleotide (FAD) pyrophosphatase that hydrolyzes FAD into AMP and flavin mononucleotide (FMN) in the spirochete's periplasm. However, orthologs of Ftp_Tp from other bacteria appear to lack this hydrolytic activity; rather, they bind and flavinylate subunits of a cytoplasmic membrane redox system (Nqr/Rnf). To further explore this dichotomy, biochemical analyses, protein crystallography, and structure-based mutagenesis were used to show that a single amino acid change (N55Y) in Ftp_Tp converts it from an Mg(2+)-dependent FAD pyrophosphatase to an FAD-binding protein. We also demonstrated that Ftp_Tp has a second enzymatic activity (Mg(2+)-FMN transferase); it flavinylates protein(s) covalently with FMN on a threonine side chain of an appropriate sequence motif using FAD as the substrate. Moreover, mutation of a metal-binding residue (D284A) eliminates Ftp_Tp's dual activities, thereby underscoring the role of Mg(2+) in the enzyme-catalyzed reactions. The posttranslational flavinylation activity that can target a periplasmic lipoprotein (TP0171) has not previously been described. The observed activities reveal the catalytic flexibility of a treponemal protein to perform multiple functions. Together, these findings imply mechanisms by which a dynamic pool of flavin cofactor is maintained and how flavoproteins are generated by Ftp_Tp locally in the T. pallidum periplasm.

PubMed: 25944861
DOI: 10.1128/mBio.00519-15

Experimental method

X-RAY DIFFRACTION (1.4 Å)