3X27

Structure of McbB in complex with tryptophan

Summary for 3X27

• Entry DOI: 10.2210/pdb3x27/pdb
• Descriptor: Cucumopine synthase, TRYPTOPHAN (3 entities in total)
• Functional Keywords: mcbb, pictet-spenglerase, lyase
• Biological source: Marinactinospora thermotolerans
• Total number of polymer chains: 4
• Total formula weight: 154631.93

Authors

Mori, T.,Sahashi, S.,Morita, H.,Abe, I. (deposition date: 2014-12-10, release date: 2015-10-28, Last modification date: 2024-10-30)

Primary citation

Mori, T.,Hoshino, S.,Sahashi, S.,Wakimoto, T.,Matsui, T.,Morita, H.,Abe, I.
Structural Basis for beta-Carboline Alkaloid Production by the Microbial Homodimeric Enzyme McbB
Chem.Biol., 22:898-906, 2015

PubMed Abstract: The β-carboline (βC) alkaloids occur throughout nature and exhibit diverse biological activities. In contrast to βC alkaloid synthesis in plants, the biosynthesis in microorganisms remains poorly understood. The recently reported McbB from Marinactinospora thermotolerans is a novel enzyme proposed to catalyze the Pictet-Spengler (PS) reaction of L-tryptophan and oxaloacetaldehyde to produce the βC scaffold of marinacarbolines. In this study, we solved the crystal structure of McbB complexed with L-tryptophan at 2.48 Å resolution, which revealed the novel protein folding of McbB and the totally different structure from those of other PS condensation catalyzing enzymes, such as strictosidine synthase and norcoclaurine synthase from plants. Structural analysis and site-directed mutagenesis confirmed that the previously proposed catalytic Glu97 at the active-site center functions as an acid and base catalyst. Remarkably, the structure-based mutants R72A and H87A, with expanded active-site cavities, newly accepted bulky phenylglyoxal as the aldehyde substrate, to produce 1-benzoyl-3-carboxy-β-carboline.

PubMed: 26120001
DOI: 10.1016/j.chembiol.2015.06.006

Experimental method

X-RAY DIFFRACTION (2.481 Å)