Ostreopexin: A hemopexin fold protein from the oyster mushroom, Pleurotus ostreatus

Ota, Katja; Mikelj, Miha; Papler, Tadeja; Leonardi, Adrijana; Križaj, Igor; Maček, Peter

doi:10.1016/j.bbapap.2013.03.027

Cited by 3 publications

(1 citation statement)

References 37 publications

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“…In addition to modulating part of the lignin-degrading machinery, this study has also provided evidence for a possible link between ssps and other genes with possible functions related to lignin degradation (Table 1). One of these is hemopexin, (id 133592), which encodes for a protein that exhibits hemin-binding properties and has been designated ostreopexin in P. ostreatus [39]. While its role in lignin degradation has not been investigated, it is conceivable that it may be involved in transferring heme to ligninolytic peroxidases in a similar manner as hemin and hemoglobin [40,41].…”

Section: Discussionmentioning

confidence: 99%

Altered Expression of Two Small Secreted Proteins (ssp4 and ssp6) Affects the Degradation of a Natural Lignocellulosic Substrate by Pleurotus ostreatus

Yarden,

Zhang,

Marcus

et al. 2023

IJMS

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Pleurotus ostreatus is a white-rot fungus that can degrade lignin in a preferential manner using a variety of extracellular enzymes, including manganese and versatile peroxidases (encoded by the vp1-3 and mnp1-6 genes, respectively). This fungus also secretes a family of structurally related small secreted proteins (SSPs) encoded by the ssp1-6 genes. Using RNA sequencing (RNA-seq), we determined that ssp4 and ssp6 are the predominant members of this gene family that were expressed by P. ostreatus during the first three weeks of growth on wheat straw. Downregulation of ssp4 in a strain harboring an ssp RNAi construct (KDssp1) was then confirmed, which, along with an increase in ssp6 transcript levels, coincided with reduced lignin degradation and the downregulation of vp2 and mnp1. In contrast, we observed an increase in the expression of genes related to pectin and side-chain hemicellulose degradation, which was accompanied by an increase in extracellular pectin-degrading capacity. Genome-wide comparisons between the KDssp1 and the wild-type strains demonstrated that ssp silencing conferred accumulated changes in gene expression at the advanced cultivation stages in an adaptive rather than an inductive mode of transcriptional response. Based on co-expression networking, crucial gene modules were identified and linked to the ssp knockdown genotype at different cultivation times. Based on these data, as well as previous studies, we propose that P. ostreatus SSPs have potential roles in modulating the lignocellulolytic and pectinolytic systems, as well as a variety of fundamental biological processes related to fungal growth and development.

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Section: Discussionmentioning

confidence: 99%

Altered Expression of Two Small Secreted Proteins (ssp4 and ssp6) Affects the Degradation of a Natural Lignocellulosic Substrate by Pleurotus ostreatus

Yarden,

Zhang,

Marcus

et al. 2023

IJMS

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Cellular Iron Uptake and Export in Mammals

2016

Iron Metabolism

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Crystal structure of a plant albumin from Cicer arietinum (chickpea) possessing hemopexin fold and hemagglutination activity

Sharma

Katre

Suresh

2015

Planta

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Crystal structure of a reported PA2 albumin from Cicer arietinum shows that it belongs to hemopexin fold family, has four beta-propeller motifs and possesses hemagglutination activity, making it different from known legume lectins. A plant albumin (PA2) from Cicer arietinum, presumably a lectin (CAL) owing to its hemagglutination activity which is inhibited by complex sugars as well as glycoproteins such as fetuin, desialylated fetuin and fibrinogen. The three-dimensional structure of this homodimeric protein has been determined using X-ray crystallography at 2.2 Å in two crystal forms: orthorhombic (P21212) and trigonal (P3). The structure determined using molecular replacement method and refined in orthorhombic crystal form reached R-factors R free 22.6 % and R work 18.2 % and in trigonal form had 22.3 and 17.9 % in the resolution range of 20.0-2.2 and 35.3-2.2 Å, respectively. Interestingly, unlike the known legume lectin fold, the structure of this homodimeric hemagglutinin belonged to hemopexin fold that consisted of four-bladed β-propeller architecture. Each subunit has a central cavity forming a channel, inside of which is lined with hydrophobic residues. The channel also bears binding sites for ligands such as calcium, sodium and chloride ions, iodine atom in the case of iodine derivative and water molecules. However, none of these ligands seem important for the sugar recognition. No monosaccharide sugar specificity could be detected using hemagglutination inhibition. Chemical modification studies identified a potential sugar-binding site per subunit molecule. Comparison of C-alpha atom positions in subunit structures showed that the deviations between the two crystal forms were more with respect to blades I and IV. Differences also existed between subunits in two forms in terms of type and site of ligand binding.

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Ostreopexin: A hemopexin fold protein from the oyster mushroom, Pleurotus ostreatus

Cited by 3 publications

References 37 publications

Altered Expression of Two Small Secreted Proteins (ssp4 and ssp6) Affects the Degradation of a Natural Lignocellulosic Substrate by Pleurotus ostreatus

Altered Expression of Two Small Secreted Proteins (ssp4 and ssp6) Affects the Degradation of a Natural Lignocellulosic Substrate by Pleurotus ostreatus

Cellular Iron Uptake and Export in Mammals

Crystal structure of a plant albumin from Cicer arietinum (chickpea) possessing hemopexin fold and hemagglutination activity

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