6OJB

Crystal Structure of Aspergillus fumigatus Ega3 complex with galactosamine

Summary for 6OJB

• Entry DOI: 10.2210/pdb6ojb/pdb
• Descriptor: Endo alpha-1,4 polygalactosaminidase, alpha-D-mannopyranose-(1-2)-[alpha-D-mannopyranose-(1-6)]alpha-D-mannopyranose-(1-3)-[alpha-D-mannopyranose-(1-3)-alpha-D-mannopyranose-(1-6)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-2)-alpha-D-mannopyranose-(1-6)-[alpha-D-mannopyranose-(1-3)]alpha-D-mannopyranose-(1-3)-beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (7 entities in total)
• Functional Keywords: galactosaminidase, (beta/alpha)-barrel, glycoside hydrolase, hydrolase
• Biological source: Neosartorya fumigata (strain ATCC MYA-4609 / Af293 / CBS 101355 / FGSC A1100)
• Total number of polymer chains: 1
• Total formula weight: 35902.72

Authors

Bamford, N.C.,Howell, P.L. (deposition date: 2019-04-11, release date: 2019-08-14, Last modification date: 2024-10-30)

Primary citation

Bamford, N.C.,Le Mauff, F.,Subramanian, A.S.,Yip, P.,Millan, C.,Zhang, Y.,Zacharias, C.,Forman, A.,Nitz, M.,Codee, J.D.C.,Uson, I.,Sheppard, D.C.,Howell, P.L.
Ega3 from the fungal pathogenAspergillus fumigatusis an endo-alpha-1,4-galactosaminidase that disrupts microbial biofilms.
J.Biol.Chem., 294:13833-13849, 2019

PubMed Abstract: is an opportunistic fungal pathogen that causes both chronic and acute invasive infections. Galactosaminogalactan (GAG) is an integral component of the biofilm matrix and a key virulence factor. GAG is a heterogeneous linear α-1,4-linked exopolysaccharide of galactose and GalNAc that is partially deacetylated after secretion. A cluster of five co-expressed genes has been linked to GAG biosynthesis and modification. One gene in this cluster, ega3, is annotated as encoding a putative α-1,4-galactosaminidase belonging to glycoside hydrolase family 114 (GH114). Herein, we show that recombinant Ega3 is an active glycoside hydrolase that disrupts GAG-dependent and Pel polysaccharide-dependent biofilms at nanomolar concentrations. Using MS and functional assays, we demonstrate that Ega3 is an endo-acting α-1,4-galactosaminidase whose activity depends on the conserved acidic residues, Asp-189 and Glu-247. X-ray crystallographic structural analysis of the apo Ega3 and an Ega3-galactosamine complex, at 1.76 and 2.09 Å resolutions, revealed a modified (β/α)-fold with a deep electronegative cleft, which upon ligand binding is capped to form a tunnel. Our structural analysis coupled with docking studies also uncovered the molecular determinants for galactosamine specificity and substrate binding at the -2 to +1 binding subsites. The findings in this study increase the structural and mechanistic understanding of the GH114 family, which has >600 members encoded by plant and opportunistic human pathogens, as well as in industrially used bacteria and fungi.

PubMed: 31416836
DOI: 10.1074/jbc.RA119.009910

Experimental method

X-RAY DIFFRACTION (2.093 Å)