Fig. 5: Superposition of the structural models of HxnX, HxnV, HxnT, and HxnW with their closest known structural homologs and cellular localization of HxnX.
From: A complete nicotinate degradation pathway in the microbial eukaryote Aspergillus nidulans
Hxn enzymes are shown in blue; the structural homologs are shown in salmon and green colors. For each model, the image to the left shows the superposition of the compared proteins in the ribbon view and includes the modeled substrate and/or cofactor. The substrate interacting side chains are shown as magnified insets in the stick view to the right of each model. FMN, FAD, and NAD cofactors are shown by gray sticks. a HxnX versus 6-NA 3-monooxygenase (NicC) from Pseudomonas putida (PDB code: 5eow)18. Thick sticks show 6-NA binding residues, while thin sticks show additional active site residues of NicC. b HxnV versus 3-hydroxybenzoate hydroxylase (MHBH) from Comamonas testosteroni (PDB code: 2dkh)22. 3HB: 3-hydroxybenzoic acid (3HB) substrate (green sticks). Sticks show the 3HB substrate-binding residues of MHBH. c HxnT versus old yellow enzyme 1 (OYE1) of Saccharomyces pastorianus (PDB code: 1oya)23. HBA: para-hydroxybenzaldehyde ligand of SpOYE1 (green sticks). Thin sticks: FMN binding residues; thick sticks: HBA binding residues of SpOYE1. d HxnW versus the polyol dehydrogenase enzyme Gox2181 from Gluconobacter oxidans (PDB code: 3awd) and carveol dehydrogenase CDH from Mycobacterium avium (PDB code: 3uve)31,32. Thick sticks: active site residues in Gox2181 and CDH30,31,32; thin sticks: residues of TG(X)3GXG NAD(P) binding motif in HxnW, characteristic of the fungal-type ketoreductases. Quality assessments of the Hxn models and superpositions with their closest known structural homologs are summarized in Supplementary Table 4. e Subcellular localization of the Gfp-HxnX fusion protein. Gfp-HxnX is co-expressed with DsRed-SKL (peroxisome targeted red fluorescent protein54,55) in strain HZS.579. Fluorescent microscopy was carried out by using Zeiss 09 and 15 filter sets for DsRed and Gfp, respectively. Conidia were germinated for 6.5 h at 37 °C on the surface coverslips submerged in MM prior to microscopy. Scale bar represents 10 μm.
