Glycan specificity of a testis-specific lectin chaperone calmegin and effects of hydrophobic interactions

Sakono, Masafumi; Seko, Akira; Takeda, Yoichi; Aikawa, Jun-ichi; Hachisu, Mitsugu; Koizumi, Akihiko; Fujikawa, Kohki; Ito, Yukishige

doi:10.1016/j.bbagen.2014.04.012

Cited by 11 publications

(7 citation statements)

References 40 publications

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“…There are several examples involving N-glycan biosynthesis during protein glycosylation. Calnexin is a lectin chaperone molecule that plays a key role in quality control of glycoprotein folding based on carbohydrate recognition of the Glc1Man9GlcNAc2 residue (16). ERGIC-53 and VIP36 are leguminous type (L-type) lectins that function as cargo receptors for trafficking of certain N-linked glycoproteins in secretory pathways of animal cells.…”

Section: Discussionmentioning

confidence: 99%

Functional control of polypeptide GalNAc-transferase 3 through an acetylation site in the C-terminal lectin domain

Lorenz¹,

Cejas²,

Bennett

et al. 2017

Biological Chemistry

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O-GalNAc glycans are important structures in cellular homeostasis. Their biosynthesis is initiated by members of the polypeptide GalNAc-transferase (ppGalNAc-T) enzyme family. Mutations in ppGalNAc-T3 isoform cause diseases (congenital disorders of glycosylation) in humans. The K626 residue located in the C-terminal β-trefoil fold of ppGalNAc-T3 was predicted to be a site with high likelihood of acetylation by CBP/p300 acetyltransferase. We used a site-directed mutagenesis approach to evaluate the role of this acetylation site in biological properties of the enzyme. Two K626 mutants of ppGalNAc-T3 (T3K626Q and T3K626A) had GalNAc-T activities lower than that of wild-type enzyme. Direct and competitive interaction assays revealed that GalNAc recognition by the lectin domain was altered in the mutants. The presence of GlcNAc glycosides affected the interaction of the three enzymes with mucin-derived peptides. In GalNAc-T activity assays, the presence of GlcNAc glycosides significantly inhibited activity of the mutant (T3K626Q) that mimicked acetylation. Our findings, taken together, reveal the crucial role of the K626 residue in the C-terminal β-trefoil fold in biological properties of human ppGalNAc-T3. We propose that acetylated residues on ppGalNAc-T3 function as control points for enzyme activity, and high level of GlcNAc glycosides promote a synergistic regulatory mechanism, leading to a metabolically disordered state.

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Section: Discussionmentioning

confidence: 99%

Functional control of polypeptide GalNAc-transferase 3 through an acetylation site in the C-terminal lectin domain

Lorenz¹,

Cejas²,

Bennett

et al. 2017

Biological Chemistry

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“…The specificity of Calmegin, the testis-specific homolog of CNX/CRT,w as also revealed by synthetic glycans. [46] 3.2. Glucosidase II Glucosidase II (G-II) is ak ey enzyme in GPQC, which initiates both the entry into (Cleavage 1)a nd the exit from (Cleavage 2)t he CNX/CRT cycle ( Figure 7A).…”

Section: Chemical Synthesisofglycoproteinsmentioning

confidence: 99%

Chemical‐Synthesis‐Based Approach to Glycoprotein Functions in the Endoplasmic Reticulum

Ito

Kajihara

Takeda

2020

Chemistry A European J

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The introduction of Asn‐linked glycans to nascent polypeptides occurs in the lumen of the endoplasmic reticulum of eukaryotic cells. After the removal of specific sugar residues, glycoproteins acquire signals in the glycoprotein quality control (GPQC) system and enter the folding cycle composed of lectin‐chaperones calnexin (CNX) and calreticulin (CRT), glucosidase II (G‐II), and UDP‐Glc:glycoprotein glucosyltransferase (UGGT). G‐II initiates glycoproteins’ entry and exit from the cycle, and UGGT serves as the “folding sensor”. This account summarizes our effort to analyze the properties of enzymes and lectins that play important roles in GPQC, especially those involved in the CNX/CRT cycle. To commence our study, general methods for the synthesis of high‐mannose‐type glycans and glycoproteins were established. Based on these, various substrates to analyze components of the GPQC were created, and properties of CRT, G‐II, and UGGT have been clarified.

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“…High-mannose-type glycans prepared by the chemo-enzymatic strategy have proven to be valuable in deciphering specificities of various CAPs in the ER. As a matter of fact, they have been employed in the analyses of malectin, [26] VIP36, [26] UGGT2, [27] calmegin, [28] and mannosidase I. [29] The renewed chemo-enzymatic approach will strengthen the basis for more comprehensive analysis of CAPs that act on high-mannose-type glycans.…”

Section: Substrate Specificity Of Gnt-i Toward M7-m3 Glycansmentioning

confidence: 99%

Construction of a High‐Mannose‐Type Glycan Library by a Renewed Top‐Down Chemo‐Enzymatic Approach

Fujikawa

Koizumi

Hachisu

et al. 2015

Chemistry A European J

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A comprehensive method for the construction of a high-mannose-type glycan library by systematic chemo-enzymatic trimming of a single Man9-based precursor was developed. It consists of the chemical synthesis of a non-natural tridecasaccharide precursor, the orthogonal demasking of the non-reducing ends, and trimming by glycosidases, which enabled a comprehensive synthesis of high-mannose-type glycans in their mono- or non-glucosylated forms. It employed glucose, isopropylidene, and N-acetylglucosamine groups for blocking the A-, B-, and C-arms, respectively. After systematic trimming of the precursor, thirty-seven high-mannose-type glycans were obtained. The power of the methodology was demonstrated by the enzymatic activity of human recombinant N-acetylglucosaminyltransferase-I toward M7-M3 glycans, clarifying the substrate specificity in the context of high-mannose-type glycans.

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Glycan specificity of a testis-specific lectin chaperone calmegin and effects of hydrophobic interactions

Cited by 11 publications

References 40 publications

Functional control of polypeptide GalNAc-transferase 3 through an acetylation site in the C-terminal lectin domain

Functional control of polypeptide GalNAc-transferase 3 through an acetylation site in the C-terminal lectin domain

Chemical‐Synthesis‐Based Approach to Glycoprotein Functions in the Endoplasmic Reticulum

Construction of a High‐Mannose‐Type Glycan Library by a Renewed Top‐Down Chemo‐Enzymatic Approach

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