Structure of jack bean chitinase

Hahn, Michael G.; Hennig, Michael; Schlesier, Bernhard; Höhne, Wolfgang-Ernst

doi:10.1107/s090744490000857x

Cited by 56 publications

(56 citation statements)

References 19 publications

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“…In such inverting enzymes, two widely separated (~9Å) acidic residues were thought to be required for catalysis. One was proposed to act as a general acid that donates a proton in the reaction, and the other as a general base that activates a nucleophilic water molecule and stabilizes a charged intermediate (Brameld and Goddard 1998;Fukamizo 2000;Hahn et al 2000). The very recent publication of the structure of class I or II chitinase from papaya bound to two GlcNAc molecules (Huet et al 2008) provided a basis for modeling the binding of four GlcNAc units in the active site, and supported the proposed reaction mechanism.…”

Section: Introductionmentioning

confidence: 76%

“…Later work supplied structures of the CMs of class II enzymes from jack bean (PDB entry 1DXJ (Hahn et al 2000)) and rice (PDB entry 2DKV (Mizuno et al 2008)) and the class I-like enzyme from Brassica juncea (leaf mustard; PDB entries 2Z37, 2Z38, 2Z39 (Ubhayasekera et al 2007)). The last differs from typical class I enzymes in that it possesses two CtBMs rather than one; however, the CM has 55-60% amino acid sequence identity to enzymes of class I and II.…”

Section: Introductionmentioning

confidence: 99%

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The first crystal structures of a family 19 class IV chitinase: the enzyme from Norway spruce

Ubhayasekera

Rawat

et al. 2009

Plant Mol Biol

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Chitinases help plants defend themselves against fungal attack, and play roles in other processes, including development. The catalytic modules of most plant chitinases belong to glycoside hydrolase family 19. We report here x-ray structures of such a module from a Norway spruce enzyme, the first for any family 19 class IV chitinase. The bi-lobed structure has a wide cleft lined by conserved residues; the most interesting for catalysis are Glu113, the proton donor, and Glu122, believed to be a general base that activate a catalytic water molecule. Comparisons to class I and II enzymes show that loop deletions in the class IV proteins make the catalytic cleft shorter and wider; from modeling studies, it is predicted that only three N-acetylglucosamine-binding subsites exist in class IV. Further, the structural comparisons suggest that the family 19 enzymes become more closed on substrate binding. Attempts to solve the structure of the complete protein including the associated chitin-binding module failed, however, modeling studies based on close relatives indicate that the binding module recognizes at most three N-acetylglucosamine units. The combined results suggest that the class IV enzymes are optimized for shorter substrates than the class I and II enzymes, or alternatively, that they are better suited for action on substrates where only small regions of chitin chain are accessible. Intact spruce chitinase is shown to possess antifungal activity, which requires the binding module; removing this module had no effect on measured chitinase activity.

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Section: Introductionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

The first crystal structures of a family 19 class IV chitinase: the enzyme from Norway spruce

Ubhayasekera

Rawat

et al. 2009

Plant Mol Biol

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“…The availability of x-ray structures for two chitinases of class II, those from barley 33,42) and jack bean, 43) each of which has $50% amino-acid identity to the catalytic module of yam chitinase, allowed homology modeling to be used as a framework for understanding the sequence data. The putative catalytic residues, Glu138 and Glu147 (the numbering assumes the first methionine is the start site), are conserved along with surrounding residues in the yam enzyme, which is in agreement with the observation that enzymes of both classes have a common (inverting) catalytic mechanism.…”

Section: Discussionmentioning

confidence: 99%

Molecular Cloning of a Genomic DNA Encoding Yam Class IV Chitinase

Mitsunaga

Iwase

Ubhayasekera

et al. 2004

Bioscience, Biotechnology, and Biochemistry

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Genomic DNA for a class IV chitinase was cloned from yam (Dioscorea opposita Thunb) leaves and sequenced. The deduced amino acid sequence shows 50 to 59% identity to class IV chitinases from other plants. The yam chitinase, however, has an additional sequence of 8 amino acids (a C-terminal extension) following the cysteine that was reported as the last amino acid for other class IV chitinases; this extension is perhaps involved in subcellular localization. A homology model based on the structure of a class II chitinase from barley was used as an aid to interpreting the available data. The analysis suggests that the class IV enzyme recognizes an even shorter segment of the substrate than class I or II enzymes. This observation might help to explain why class IV enzymes are better suited to attack against pathogen cell walls.

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“…GH19 ailesinin 3 boyutlu yapısı ilk olarak Hart et al (1996) tarafından arpa bitkisinden Sınıf II kitinazıyla rapor edilmiştir. Bu çalışmadan sonra fasulye bitkisinde de yapısı ortaya konmuştur (Hahn et al, 2000).…”

Section: Bitki Kitinazlarıunclassified

Plant Chitinases: Molecular Structure, Importance and Utilizations

Hiloğlu¹

2017

jist

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Kitinaz proteinleri biyolojik sistemlerde doğada yaygın şekilde bulunurlar. Bitki kitinazları, glikozid hidrolaz gen ailesinden GH18 ve GH19 aileleri içerisinde yer almaktadır. Yedi sınıfa (I-VII) ayrılan bitki kitinazları, yapıları, amino asit dizi benzerlikleri, substrat spesifiteleri, kataliz mekanizmaları ve inhibitör hassasiyetlerine göre birbirlerinden farklılaşırlar. GH19 ailesinde bulunan sınıf I, II, IV, VI ve VII kitinazlarının en önemlileri patojen bağlantılı proteinlerden oluşmaktadır. Genel olarak bitki kitinazları patojenlere ve abiyotik faktörlere yanıt olarak bitkiler tarafından üretilirler. Bunlar, bitkilerde antifungal, antibakteriyel, insektisidal, nematisidal ve antiviral savunma mekanizmaları geliştirirler. Kitinazlar, gen mühendisliği uygulamaları aracılığıyla ticari öneme sahip bitkilere aktarılmaktadır. Böylece, biyotik ve abiyotik etkilere karşı dirençli bitkiler geliştirilmektedir. Bu derlemede, bitki kitinazlarının özellikleri, önemleri ve kullanımları hakkında bilgiler verilmiştir.

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Structure of jack bean chitinase

Cited by 56 publications

References 19 publications

The first crystal structures of a family 19 class IV chitinase: the enzyme from Norway spruce

The first crystal structures of a family 19 class IV chitinase: the enzyme from Norway spruce

Molecular Cloning of a Genomic DNA Encoding Yam Class IV Chitinase

Plant Chitinases: Molecular Structure, Importance and Utilizations

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