3a71

Publication Abstract from PubMed

Arabinanase Abnx from Penicillium chrysogenum 31B, which belongs to the GH93 family, releases arabinobiose from the nonreducing terminus of alpha-1,5-L-arabinan, which is distributed in the primary cell walls of higher plants. Crystal structures of Abnx and of its complex with arabinobiose were determined at the high resolutions of 1.14 A to an R(work) of 10.7% (R(free) = 12.8%) and 1.04 A to an R(work) of 10.4% (R(free) = 12.5%). Abnx has a six-bladed beta-propeller fold with a typical ring-closure mode called `Velcro', in which the last four-stranded beta-sheet is completed by the incorporation of a strand from the N-terminus. Catalytic residues which act as a nucleophile and an acid/base were proposed from the structures and confirmed by site-directed mutagenesis. The substrate-binding groove is enclosed at one end by two residues, Glu64 and Tyr66, which contribute to the recognition of the nonreducing chain end of the polysaccharide. A comparison with the related enzyme Arb93A which has a quite similar overall structure suggested that Abnx has different mechanisms to funnel substrates to the active site and/or to stabilize the transition state.

High-resolution structure of exo-arabinanase from Penicillium chrysogenum.,Sogabe Y, Kitatani T, Yamaguchi A, Kinoshita T, Adachi H, Takano K, Inoue T, Mori Y, Matsumura H, Sakamoto T, Tada T Acta Crystallogr D Biol Crystallogr. 2011 May;67(Pt 5):415-22. Epub 2011, Apr 13. PMID:21543843^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.