Larsen S

References (4)

Title : The structural basis of fungal glucuronoyl esterase activity on natural substrates - Ernst_2020_Nat.Commun_11_1026
Author(s) : Ernst HA , Mosbech C , Langkilde AE , Westh P , Meyer AS , Agger JW , Larsen S
Ref : Nat Commun , 11 :1026 , 2020
Abstract : Structural and functional studies were conducted of the glucuronoyl esterase (GE) from Cerrena unicolor (CuGE), an enzyme catalyzing cleavage of lignin-carbohydrate ester bonds. CuGE is an alpha/beta-hydrolase belonging to carbohydrate esterase family 15 (CE15). The enzyme is modular, comprised of a catalytic and a carbohydrate-binding domain. SAXS data show CuGE as an elongated rigid molecule where the two domains are connected by a rigid linker. Detailed structural information of the catalytic domain in its apo- and inactivated form and complexes with aldouronic acids reveal well-defined binding of the 4-O-methyl-a-D-glucuronoyl moiety, not influenced by the nature of the attached xylo-oligosaccharide. Structural and sequence comparisons within CE15 enzymes reveal two distinct structural subgroups. CuGE belongs to the group of fungal CE15-B enzymes with an open and flat substrate-binding site. The interactions between CuGE and its natural substrates are explained and rationalized by the structural results, microscale thermophoresis and isothermal calorimetry.
ESTHER : Ernst_2020_Nat.Commun_11_1026
PubMedSearch : Ernst_2020_Nat.Commun_11_1026
PubMedID: 32094331
Gene_locus related to this paper: cerui-gce

Title : Upper susceptibility threshold limits with confidence intervals: a method to identify normal and abnormal population values for laboratory toxicological parameters, based on acetylcholinesterase activities in sea lice - Fallang_2006_Pest.Manag.Sci_62_208
Author(s) : Fallang A , Larsen S , Horsberg TE
Ref : Pest Manag Sci , 62 :208 , 2006
Abstract : The interpretation and importance of comparing field values of susceptibility to pesticides with a laboratory reference strain that might bear little resemblance to the actual situation in the field are problematic and a continuing subject of debate. In this paper a procedure for defining a 'normal sensitive' population from a field study of 383 individuals to provide a basis for analysing and interpreting in vitro results is described and examined. Instead of using only the 95th percentile, the upper and lower confidence limits for the 95th percentile were also compared to select the best estimation of the limit for the normal material. A field population constrained by the upper confidence limit for the 95th percentile provides appropriate descriptions of the normal material in this study. This approach should prove useful in studies of pesticide resistance in field populations.
ESTHER : Fallang_2006_Pest.Manag.Sci_62_208
PubMedSearch : Fallang_2006_Pest.Manag.Sci_62_208
PubMedID: 16475215

Title : A branched N-linked glycan at atomic resolution in the 1.12 A structure of rhamnogalacturonan acetylesterase - Molgaard_2002_Acta.Crystallogr.D.Biol.Crystallogr_58_111
Author(s) : Molgaard A , Larsen S
Ref : Acta Crystallographica D Biol Crystallogr , 58 :111 , 2002
Abstract : The crystal structure of the glycoprotein rhamnogalacturonan acetylesterase from Aspergillus aculeatus has been refined to a resolution of 1.12 A using synchrotron data collected at 263 K. Both of the two putative N-glycosylation sites at Asn104 and Asn182 are glycosylated and, owing to crystal contacts, the glycan structure at Asn182 is exceptionally well defined in the electron-density maps, showing the six-carbohydrate structure Manalpha1-6(Manalpha1-3)Manalpha1-6Manbeta1-4GlcNAcbeta1-4GlcNAcbeta-Asn182. Equivalent carbohydrate residues were restrained to have similar geometries, but were refined without target values. The refined bond lengths and angles were compared with the values obtained from small-molecule studies that form the basis for the dictionaries used for glycoprotein refinement.
ESTHER : Molgaard_2002_Acta.Crystallogr.D.Biol.Crystallogr_58_111
PubMedSearch : Molgaard_2002_Acta.Crystallogr.D.Biol.Crystallogr_58_111
PubMedID: 11752785

Title : Rhamnogalacturonan acetylesterase elucidates the structure and function of a new family of hydrolases - Molgaard_2000_Structure.Fold.Des_8_373
Author(s) : Molgaard A , Kauppinen S , Larsen S
Ref : Structure Fold Des , 8 :373 , 2000
Abstract : BACKGROUND The complex polysaccharide rhamnogalacturonan constitutes a major part of the hairy region of pectin. It can have different types of carbohydrate sidechains attached to the rhamnose residues in the backbone of alternating rhamnose and galacturonic acid residues; the galacturonic acid residues can be methylated or acetylated. Aspergillus aculeatus produces enzymes that are able to perform a synergistic degradation of rhamnogalacturonan. The deacetylation of the backbone by rhamnogalacturonan acetylesterase (RGAE) is an essential prerequisite for the subsequent action of the enzymes that cleave the glycosidic bonds. RESULTS: The structure of RGAE has been determined at 1.55 A resolution. RGAE folds into an alpha/beta/alpha structure. The active site of RGAE is an open cleft containing a serine-histidine-aspartic acid catalytic triad. The position of the three residues relative to the central parallel beta sheet and the lack of the nucleophilic elbow motif found in structures possessing the alpha/beta hydrolase fold show that RGAE does not belong to the alpha/beta hydrolase family.
CONCLUSIONS: Structural and sequence comparisons have revealed that, despite very low sequence similarities, RGAE is related to seven other proteins. They are all members of a new hydrolase family, the SGNH-hydrolase family, which includes the carbohydrate esterase family 12 as a distinct subfamily. The SGNH-hydrolase family is characterised by having four conserved blocks of residues, each with one completely conserved residue; serine, glycine, asparagine and histidine, respectively. Each of the four residues plays a role in the catalytic function.
ESTHER : Molgaard_2000_Structure.Fold.Des_8_373
PubMedSearch : Molgaard_2000_Structure.Fold.Des_8_373
PubMedID: 10801485