5D6T

Crystal Structure of Aspergillus clavatus Sph3 in complex with GalNAc

Summary for 5D6T

• Entry DOI: 10.2210/pdb5d6t/pdb
• Related: 5C5G
• Descriptor: SPHERULIN-4, CHLORIDE ION, SULFATE ION, ... (5 entities in total)
• Functional Keywords: spherulin, (beta/alpha) barrel, glycoside hydrolase, galnac complex, hydrolase
• Biological source: Aspergillus clavatus (strain ATCC 1007 / CBS 513.65 / DSM 816 / NCTC 3887 / NRRL 1)
• Total number of polymer chains: 1
• Total formula weight: 30413.11

Authors

Bamford, N.C.,Little, D.J.,Howell, P.L. (deposition date: 2015-08-12, release date: 2015-09-16, Last modification date: 2023-09-27)

Primary citation

Bamford, N.C.,Snarr, B.D.,Gravelat, F.N.,Little, D.J.,Lee, M.J.,Zacharias, C.A.,Chabot, J.C.,Geller, A.M.,Baptista, S.D.,Baker, P.,Robinson, H.,Howell, P.L.,Sheppard, D.C.
Sph3 Is a Glycoside Hydrolase Required for the Biosynthesis of Galactosaminogalactan in Aspergillus fumigatus.
J.Biol.Chem., 290:27438-27450, 2015

PubMed Abstract: Aspergillus fumigatus is the most virulent species within the Aspergillus genus and causes invasive infections with high mortality rates. The exopolysaccharide galactosaminogalactan (GAG) contributes to the virulence of A. fumigatus. A co-regulated five-gene cluster has been identified and proposed to encode the proteins required for GAG biosynthesis. One of these genes, sph3, is predicted to encode a protein belonging to the spherulin 4 family, a protein family with no known function. Construction of an sph3-deficient mutant demonstrated that the gene is necessary for GAG production. To determine the role of Sph3 in GAG biosynthesis, we determined the structure of Aspergillus clavatus Sph3 to 1.25 Å. The structure revealed a (β/α)8 fold, with similarities to glycoside hydrolase families 18, 27, and 84. Recombinant Sph3 displayed hydrolytic activity against both purified and cell wall-associated GAG. Structural and sequence alignments identified three conserved acidic residues, Asp-166, Glu-167, and Glu-222, that are located within the putative active site groove. In vitro and in vivo mutagenesis analysis demonstrated that all three residues are important for activity. Variants of Asp-166 yielded the greatest decrease in activity suggesting a role in catalysis. This work shows that Sph3 is a glycoside hydrolase essential for GAG production and defines a new glycoside hydrolase family, GH135.

PubMed: 26342082
DOI: 10.1074/jbc.M115.679050

Experimental method

X-RAY DIFFRACTION (1.93 Å)