Download MendeleyStructure-based functionality of a multi-domain periplasmic chitodextrinase from marine bacterium Vibrio cholerae.
Khumnonkhro, K., Chongrungreang, T., Sakuda, S., Robinson, R.C., Fukamizo, T., Suginta, W.(2026) J Biol Chem 302: 113351-113351
- PubMed: 42480705 Search on PubMed
- DOI: https://doi.org/10.1016/j.jbc.2026.113351
- Primary Citation Related Structures:
9X9R, 9XDX - PubMed Abstract:
Periplasmic chitodextrinase (Chdx) is involved in chitin metabolism in Vibrio species. Chdxs from Vibrio cholerae (VcChdx) and Vibrio harveyi consist of six domains: an N-terminal family 5/12 carbohydrate-binding module (N-CBM), two immunoglobulin-like domains (IgL-1 and IgL-2), a GH18 catalytic domain (CatD), a chitin-binding domain (ChBD), and a C-terminal family 5/12 carbohydrate-binding module (C-CBM). We produced recombinant VcChdx, which exhibited a single band at 116 kDa on SDS-PAGE. VcChdx fwas successfully crystallized in the ligand-free and bound state with the inhibitor allosamidin, providing insights into the catalytic center and substrate-binding groove of CatD, which tightly interacts with ChBD. However, no electron density was observed for two CBMs and two IgLs, probably due to their high conformational mobility. Size-exclusion chromatography coupled with multi-angle light scattering and small-angle X-ray scattering revealed the overall architecture of multi-modular VcChdx, in which the individual folded domains are extended in solution. Isothermal titration calorimetry analysis indicated that the interaction between VcChdx and allosamidin was enthalpy-driven with moderate affinity (K d = 1.58 ± 0.48 μm). HPLC analysis of the reaction products from the substrates, chitooligosaccharides, (GlcNAc) n (n = 2-6), indicated that VcChdx hydrolyzes (GlcNAc) n in an endo-splitting manner. Among tested substrates, the specific activity was highest toward (GlcNAc) 6 . Taken together, VcChdx is a GH18 enzyme with an elongated, multi-modular structure and endo-splitting activity toward soluble (GlcNAc) n . It likely acts cooperatively with chitoporin localized to the outer membrane, which preferentially translocates (GlcNAc) 6 into the periplasm.
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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