I04-1-Macromolecular Crystallography (fixed wavelength)
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Diamond Proposal Number(s):
[18598]
Open Access
Abstract: Many secreted eukaryotic proteins are N-glycosylated with oligosaccharides composed of a high-mannose N-glycan core and, in the specific case of yeast cell-wall proteins, an extended α-1,6-mannan backbone carrying a number of α-1,2- and α-1,3-mannose substituents of varying lengths. α-Mannosidases from CAZy family GH92 release terminal mannose residues from these N-glycans, providing access for the α-endomannanases, which then degrade the α-mannan backbone. Most characterized GH92 α-mannosidases consist of a single catalytic domain, while a few have extra domains including putative carbohydrate-binding modules (CBMs). To date, neither the function nor the structure of a multi-domain GH92 α-mannosidase CBM has been characterized. Here, the biochemical investigation and crystal structure of the full-length five-domain GH92 α-1,2-mannosidase from Neobacillus novalis (NnGH92) with mannoimidazole bound in the active site and an additional mannoimidazole bound to the N-terminal CBM32 are reported. The structure of the catalytic domain is very similar to that reported for the GH92 α-mannosidase Bt3990 from Bacteroides thetaiotaomicron, with the substrate-binding site being highly conserved. The function of the CBM32s and other NnGH92 domains was investigated by their sequential deletion and suggested that whilst their binding to the catalytic domain was crucial for the overall structural integrity of the enzyme, they appear to have little impact on the binding affinity to the yeast α-mannan substrate. These new findings provide a better understanding of how to select and optimize other multi-domain bacterial GH92 α-mannosidases for the degradation of yeast α-mannan or mannose-rich glycans.
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May 2023
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I04-Macromolecular Crystallography
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Olga V.
Moroz
,
Elena
Blagova
,
Andrey A.
Lebedev
,
Filomeno
Sanchez Rodriguez
,
Daniel J.
Rigden
,
Jeppe
Wegener Tams
,
Reinhard
Wilting
,
Jan Kjølhede
Vester
,
Emily
Longhi
,
Gustav
Hammerich Hansen
,
Kristian
Bertel Rømer Mørkeberg Krogh
,
Roland A.
Pache
,
Gideon
Davies
,
Keith S.
Wilson
Diamond Proposal Number(s):
[18598]
Abstract: β-Galactosidases catalyse the hydrolysis of lactose into galactose and glucose; as an alternative reaction, some β-galactosidases also catalyse the formation of galactooligosaccharides by transglycosylation. Both reactions have industrial importance: lactose hydrolysis is used to produce lactose-free milk, while galactooligosaccharides have been shown to act as prebiotics. For some multi-domain β-galactosidases, the hydrolysis/transglycosylation ratio can be modified by the truncation of carbohydrate-binding modules. Here, an analysis of BbgIII, a multidomain β-galactosidase from Bifidobacterium bifidum, is presented. The X-ray structure has been determined of an intact protein corresponding to a gene construct of eight domains. The use of evolutionary covariance-based predictions made sequence docking in low-resolution areas of the model spectacularly easy, confirming the relevance of this rapidly developing deep-learning-based technique for model building. The structure revealed two alternative orientations of the CBM32 carbohydrate-binding module relative to the GH2 catalytic domain in the six crystallographically independent chains. In one orientation the CBM32 domain covers the entrance to the active site of the enzyme, while in the other orientation the active site is open, suggesting a possible mechanism for switching between the two activities of the enzyme, namely lactose hydrolysis and transgalactosylation. The location of the carbohydrate-binding site of the CBM32 domain on the opposite site of the module to where it comes into contact with the catalytic GH2 domain is consistent with its involvement in adherence to host cells. The role of the CBM32 domain in switching between hydrolysis and transglycosylation modes offers protein-engineering opportunities for selective β-galactosidase modification for industrial purposes in the future.
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Dec 2021
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I04-1-Macromolecular Crystallography (fixed wavelength)
I24-Microfocus Macromolecular Crystallography
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Olga V.
Moroz
,
Elena
Blagova
,
Edward
Taylor
,
Johan
Turkenburg
,
Lars K.
Skov
,
Garry P.
Gippert
,
Kirk M.
Schnorr
,
Li
Ming
,
Liu
Ye
,
Mikkel
Klausen
,
Marianne T.
Cohn
,
Esben G. W.
Schmidt
,
Søren
Nymand-Grarup
,
Gideon J.
Davies
,
Keith S.
Wilson
Diamond Proposal Number(s):
[13587, 7864]
Open Access
Abstract: Muramidases/lysozymes hydrolyse the peptidoglycan component of the bacterial cell wall. They are found in many of the glycoside hydrolase (GH) families. Family GH25 contains muramidases/lysozymes, known as CH type lysozymes, as they were initially discovered in the Chalaropsis species of fungus. The characterized enzymes from GH25 exhibit both β-1,4-N-acetyl- and β-1,4-N,6-O-diacetylmuramidase activities, cleaving the β-1,4-glycosidic bond between N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) moieties in the carbohydrate backbone of bacterial peptidoglycan. Here, a set of fungal GH25 muramidases were identified from a sequence search, cloned and expressed and screened for their ability to digest bacterial peptidoglycan, to be used in a commercial application in chicken feed. The screen identified the enzyme from Acremonium alcalophilum JCM 736 as a suitable candidate for this purpose and its relevant biochemical and biophysical and properties are described. We report the crystal structure of the A. alcalophilum enzyme at atomic, 0.78 Å resolution, together with that of its homologue from Trichobolus zukalii at 1.4 Å, and compare these with the structures of homologues. GH25 enzymes offer a new solution in animal feed applications such as for processing bacterial debris in the animal gut.
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Mar 2021
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I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[9948]
Open Access
Abstract: Background: Several examples have emerged of enzymes where slow conformational changes are of key importance for function and where low populated conformations in the resting enzyme resemble the conformations of intermediate states in the catalytic process. Previous work on the subtilisin protease, Savinase, from Bacillus lentus by NMR spectroscopy suggested that this enzyme undergoes slow conformational dynamics around the substrate binding site. However, the functional importance of such dynamics is unknown. Methods: Here we have probed the conformational heterogeneity in Savinase by following the temperature dependent chemical shift changes. In addition, we have measured changes in the local stability of the enzyme when the inhibitor phenylmethylsulfonyl fluoride is bound using hydrogen-deuterium exchange mass spectrometry (HDX-MS). Finally, we have used X-ray crystallography to compare electron densities collected at cryogenic and ambient temperatures and searched for possible low populated alternative conformations in the crystals. Results: The NMR temperature titration shows that Savinase is most flexible around the active site, but no distinct alternative states could be identified. The HDX shows that modification of Savinase with inhibitor has very little impact on the stability of hydrogen bonds and solvent accessibility of the backbone. The most pronounced structural heterogeneities detected in the diffraction data are limited to alternative side-chain rotamers and a short peptide segment that has an alternative main-chain conformation in the crystal at cryo conditions. Collectively, our data show that there is very little structural heterogeneity in the resting state of Savinase and hence that Savinase does not rely on conformational selection to drive the catalytic process.
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Jun 2020
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I02-Macromolecular Crystallography
I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[306, 7864]
Open Access
Abstract: Muramidases/lysozymes are important bio-molecules, which cleave the glycan backbone in the peptidoglycan polymer found in bacterial cell walls. The glycoside hydrolase (GH) family 22 C-type lysozyme, from the folivorous bird Opisthocomus hoazin (stinkbird), was expressed in Aspergillus oryzae, and a set of variants was produced. All variants were enzymatically active, including those designed to probe key differences between the Hoatzin enzyme and Hen Egg White lysozyme. Four variants showed improved thermostability at pH 4.7, compared to the wild type. The X-ray structure of the enzyme was determined in the apo form and in complex with chitin oligomers. Bioinformatic analysis of avian GH22 amino acid sequences showed that they separate out into three distinct subgroups (chicken-like birds, sea birds and other birds). The Hoatzin is found in the “other birds” group and we propose that this represents a new cluster of avian upper-gut enzymes.
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Nov 2019
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I02-Macromolecular Crystallography
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Christian
Roth
,
Olga V.
Moroz
,
Johan P.
Turkenburg
,
Elena
Blagova
,
Jitka
Waterman
,
Antonio
Ariza
,
Li
Ming
,
Sun
Tianqi
,
Carsten
Andersen
,
Gideon J.
Davies
,
Keith S.
Wilson
Diamond Proposal Number(s):
[1221, 9948]
Open Access
Abstract: Amylases are probably the best studied glycoside hydrolases and have a huge biotechnological value for industrial processes on starch. Multiple amylases from fungi and microbes are currently in use. Whereas bacterial amylases are well suited for many industrial processes due to their high stability, fungal amylases are recognized as safe and are preferred in the food industry, although they lack the pH tolerance and stability of their bacterial counterparts. Here, we describe three amylases, two of which have a broad pH spectrum extending to pH 8 and higher stability well suited for a broad set of industrial applications. These enzymes have the characteristic GH13 α-amylase fold with a central (β/α)8-domain, an insertion domain with the canonical calcium binding site and a C-terminal β-sandwich domain. The active site was identified based on the binding of the inhibitor acarbose in form of a transglycosylation product, in the amylases from Thamnidium elegans and Cordyceps farinosa. The three amylases have shortened loops flanking the nonreducing end of the substrate binding cleft, creating a more open crevice. Moreover, a potential novel binding site in the C-terminal domain of the Cordyceps enzyme was identified, which might be part of a starch interaction site. In addition, Cordyceps farinosa amylase presented a successful example of using the microseed matrix screening technique to significantly speed-up crystallization.
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Oct 2019
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I02-Macromolecular Crystallography
I04-1-Macromolecular Crystallography (fixed wavelength)
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Olga V.
Moroz
,
Elena
Blagova
,
Verena
Reiser
,
Rakhi
Saikia
,
Sohel
Dalal
,
Christian Isak
Jørgensen
,
Vikram K.
Bhatia
,
Lone
Baunsgaard
,
Birgitte
Andersen
,
Allan
Svendsen
,
Keith S.
Wilson
Diamond Proposal Number(s):
[7864, 9948]
Open Access
Abstract: Many proteins are synthesized as precursors, with propeptides playing a variety of roles such as assisting in folding or preventing them from being active within the cell. While the precise role of the propeptide in fungal lipases is not completely understood, it was previously reported that mutations in the propeptide region of the Rhizomucor miehei lipase have an influence on the activity of the mature enzyme, stressing the importance of the amino acid composition of this region. We here report two structures of this enzyme in complex with its propeptide, which suggests that the latter plays a role in the correct maturation of the enzyme. Most importantly, we demonstrate that the propeptide shows inhibition of lipase activity in standard lipase assays and propose that an important role of the propeptide is to ensure that the enzyme is not active during its expression pathway in the original host.
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Jun 2019
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I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
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Sybrin P.
Schröder
,
Casper
De Boer
,
Nicholas G. S.
Mcgregor
,
Rhianna J.
Rowland
,
Olga
Moroz
,
Elena
Blagova
,
Jos
Reijngoud
,
Mark
Arentshorst
,
David
Osborn
,
Marc D.
Morant
,
Eric
Abbate
,
Mary A.
Stringer
,
Kristian B. R. M.
Krogh
,
Lluís
Raich
,
Carme
Rovira
,
Jean-Guy
Berrin
,
Gilles P.
Van Wezel
,
Arthur F. J.
Ram
,
Bogdan I.
Florea
,
Gijsbert A.
Van Der Marel
,
Jeroen D. C.
Codée
,
Keith S.
Wilson
,
Liang
Wu
,
Gideon J.
Davies
,
Herman S.
Overkleeft
Diamond Proposal Number(s):
[13587]
Abstract: Plant polysaccharides represent a virtually unlimited feedstock for the generation of biofuels and other commodities. However, the extraordinary recalcitrance of plant polysaccharides toward breakdown necessitates a continued search for enzymes that degrade these materials efficiently under defined conditions. Activity-based protein profiling provides a route for the functional discovery of such enzymes in complex mixtures and under industrially relevant conditions. Here, we show the detection and identification of β-xylosidases and endo-β-1,4-xylanases in the secretomes of Aspergillus niger, by the use of chemical probes inspired by the β-glucosidase inhibitor cyclophellitol. Furthermore, we demonstrate the use of these activity-based probes (ABPs) to assess enzyme–substrate specificities, thermal stabilities, and other biotechnologically relevant parameters. Our experiments highlight the utility of ABPs as promising tools for the discovery of relevant enzymes useful for biomass breakdown.
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May 2019
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I04-Macromolecular Crystallography
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Pernille
Von Freiesleben
,
Olga V.
Moroz
,
Elena
Blagova
,
Mathias
Wiemann
,
Nikolaj
Spodsberg
,
Jane W.
Agger
,
Gideon J.
Davies
,
Keith S.
Wilson
,
Henrik
Stålbrand
,
Anne S.
Meyer
,
Kristian B. R. M.
Krogh
Diamond Proposal Number(s):
[13587]
Open Access
Abstract: Endo-β(1 → 4)-mannanases (endomannanases) catalyse degradation of β-mannans, an abundant class of plant polysaccharides. This study investigates structural features and substrate binding of YpenMan26A, a non-CBM carrying endomannanase from Yunnania penicillata. Structural and sequence comparisons to other fungal family GH26 endomannanases showed high sequence similarities and conserved binding residues, indicating that fungal GH26 endomannanases accommodate galactopyranosyl units in the −3 and −2 subsites. Two striking amino acid differences in the active site were found when the YpenMan26A structure was compared to a homology model of Wsp.Man26A from Westerdykella sp. and the sequences of nine other fungal GH26 endomannanases. Two YpenMan26A mutants, W110H and D37T, inspired by differences observed in Wsp.Man26A, produced a shift in how mannopentaose bound across the active site cleft and a decreased affinity for galactose in the −2 subsite, respectively, compared to YpenMan26A. YpenMan26A was moreover found to have a flexible surface loop in the position where PansMan26A from Podospora anserina has an α-helix (α9) which interacts with its family 35 CBM. Sequence alignment inferred that the core structure of fungal GH26 endomannanases differ depending on the natural presence of this type of CBM. These new findings have implications for selecting and optimising these enzymes for galactomannandegradation.
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Feb 2019
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I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[7864, 9948]
Open Access
Abstract: α-Amylases are glycoside hydrolases that break the α-1,4 bonds in starch and related glycans. The degradation of starch is rendered difficult by the presence of varying degrees of α-1,6 branch points and their possible accommodation within the active centre of α-amylase enzymes. Given the myriad industrial uses for starch and thus also for α-amylase-catalysed starch degradation and modification, there is considerable interest in how different α-amylases might accommodate these branches, thus impacting on the potential processing of highly branched post-hydrolysis remnants (known as limit dextrins) and societal applications. Here, it was sought to probe the branch-point accommodation of the Alicyclobacillus sp. CAZy family GH13 α-amylase AliC, prompted by the observation of a molecule of glucose in a position that may represent a branch point in an acarbose complex solved at 2.1 Å resolution. Limit digest analysis by two-dimensional NMR using both pullulan (a regular linear polysaccharide of α-1,4, α-1,4, α-1,6 repeating trisaccharides) and amylopectin starch showed how the Alicyclobacillus sp. enzyme could accept α-1,6 branches in at least the −2, +1 and +2 subsites, consistent with the three-dimensional structures with glucosyl moieties in the +1 and +2 subsites and the solvent-exposure of the −2 subsite 6-hydroxyl group. Together, the work provides a rare insight into branch-point acceptance in these industrial catalysts.
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Jan 2019
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