Loosenin-Like Proteins from
            <i>Phanerochaete carnosa</i>
            Impact Both Cellulose and Chitin Fiber Networks

Monschein, Mareike; Ioannou, Eleni; Koitto, Taru; Amin, Leamon A K M Al; Varis, Jutta; Wagner, Edward R.; Mikkonen, Kirsi S.; Cosgrove, Daniel J.; Master, Emma R.

doi:10.1128/aem.01863-22

Cited by 4 publications

(3 citation statements)

References 70 publications

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“…Study by researchers at the Autonomous University of the State of Morelos, Mexico (Quiroz-Castañeda et al, 2011), which coined the term loosenin, describes a loosenin isolated from the white-rot fungus Bjerkandera adusta with a capability to loosen cotton fibres. A recent study on the substrate binding of loosenins, demonstrated loosenin binding preference for chitin, suggesting a function in fungal cell wall morphogenesis (Monschein et al, 2023). Development of new methods for action mechanism determination would be beneficial in order to study non-hydrolytic proteins, as an absence of activity is a result difficult to publish.…”

Section: Discussionmentioning

confidence: 99%

“…These proteins were first discovered in Bjerkandera adusta (Quiroz-Castañeda et al, 2011). Loosenins exhibit cellulose fibril loosening behaviour, while it is unclear whether fungi utilize these proteins mainly in pathogenic mechanisms or they serve an analogous function to expansins in plants (Monschein et al, 2023;Quiroz-Castañeda et al, 2011). No structure of loosenins has been experimentally obtained to this date, therefore all structure comparisons rely on homology modelling.…”

Section: Fungal Homologues To Plant Expansinsmentioning

confidence: 99%

“…Similar to GH45 subfamily C enzymes, loosenins have conserved an aspartic acid residue at the same location as the catalytic acid. Moreover, the alternate base of subfamily C members is also present in loosenins, yet loosenins exhibit no hydrolytic activity on cellulosic substrates (Monschein et al, 2023).…”

Section: Fungal Homologues To Plant Expansinsmentioning

confidence: 99%

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Structure and function studies of GH45 glycoside hydrolases

Okmane¹

2023

Acta Universitatis Agriculturae Sueciae

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The enzymatic hydrolysis of lignocellulosic material in nature is carried out by a plethora of cellulases. Glycoside hydrolase family 45 (GH45) enzymes are small cellulases most commonly found in fungi that catalyse the hydrolysis of β(1→4) linked glucans. Additionally, GH45 enzymes display a structural resemblance to non-hydrolytic protein groups such as expansins and loosenins. In this thesis, the distinctness of GH45 enzymes from different subfamilies was explored. The enzymatic activity of GH45 enzymes from Humicola insolens (HiCel45A), Mytilus edulis (MeCel45A), Trichoderma reesei (TrCel45A), Phanerochaete chrysosporium (PcCel45A), Gloeophyllum trabeum (GtCel45A) was demonstrated. Among the tested substrates were barley betaglucan, konjac glucomannan, carboxymethyl cellulose, and cellohexaose. Initial hydrolysis rates and hydrolysis yields were determined by reducing sugar assays, product formation was analysed using NMR spectroscopy and HPLC. The subfamily B and C enzymes exhibited mannanase activity, and the subfamily B enzyme MeCel45A appeared cold adapted in comparison to TrCel45A. GH45 enzymes are known to act using an inverting action mechanism. This action mechanism had not been experimentally demonstrated in subfamilies B and C, however. Here experimental evidence is provided for the inverting nature of GH45 enzymes from all subfamilies. Comparisons of GH45 enzyme structures were carried out and the first crystal structure of a GH45 subfamily C enzyme from the brown-rot fungus G. trabeum was reported at 1.3 Å resolution. Furthermore, structure and function investigations were done on an isotopically labelled Cel45A from the white-rot fungus P. chrysosporium using NMR spectroscopy. PcCel45A was expressed in Pichia pastoris with 13C and 15N labelling. A nearly complete assignment of 1 H, 13C and 15N backbone resonances was obtained and the interaction of 15Nlabelled PcCel45A with cellobiose was studied.

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Section: Discussionmentioning

confidence: 99%

Section: Fungal Homologues To Plant Expansinsmentioning

confidence: 99%

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Structure and function studies of GH45 glycoside hydrolases

Okmane¹

2023

Acta Universitatis Agriculturae Sueciae

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Comparative assessment of chemical and biochemical approaches for the activation of lignocellulosic materials and emerging opportunities for expansin-related proteins

Hiltunen,

Sapkota,

Ioannou

et al. 2023

Cellulose

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Cellulose activation is a necessary step in many industrial processes including production of cellulose derivatives, regenerated cellulose, biofuels and biochemicals. Expansins and expansin-related proteins have been shown to disrupt the fibrillar aggregation and loosen the structure of lignocellulosic materials but typically lack lytic activity. Therefore, they offer a new but rather unexploited possibility for biomass to obtain better accessibility and reactivity. From an applied perspective, expansin-related proteins have been investigated for their potential to promote enzymatic hydrolysis of cellulosic substrates for the purpose of producing biofuels. The aim of this review is to compare conventional and emerging technologies relevant to cellulose activation, and critically evaluate the potential of expansin-related proteins for this purpose. As part of this assessment, methods to evaluate the action of expansin-related proteins on cellulosic substrates are summarized, and reported impacts are discussed in relation to source of the cellulosic substrate and treatment conditions. An outlook on prospective applications of expansin-related proteins is presented.

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