Structural and functional evolution of chitinase‐like proteins from plants

Abstract

The plant genome contains a large number of sequences that encode catalytically inactive chitinases referred to as chitinase-like proteins (CLPs). Although CLPs share high sequence and structural homology with chitinases of glycosyl hydrolase 18 (TIM barrel domain) and 19 families, they may lack the binding/catalytic activity. Molecular genetic analysis revealed that gene duplication events followed by mutation in the existing chitinase gene have resulted in the loss of activity. The evidences show that adaptive functional diversification of the CLPs has been achieved through alterations in the flexible regions than in the rigid structural elements. The CLPs plays an important role in the defense response against pathogenic attack, biotic and abiotic stress. They are also involved in the growth and developmental processes of plants. Since the physiological roles of CLPs are similar to chitinase, such mutations have led to plurifunctional enzymes. The biochemical and structural characterization of the CLPs is essential for understanding their roles and to develop potential utility in biotechnological industries. This review sheds light on the structure-function evolution of CLPs from chitinases.

A Na2CO3-responsive chitinase gene fromChinese wildryeimprove pathogen resistance and saline-alkali stress tolerance in transgenic tobacco and maize

“…71 Chitinase is one of the important enzyme family that has been found to involve in such 72 a mechanism of divergent biological functions. Chitinases (EC 3.2.1.14) are a family of 73 glycosyl hydrolases (GHs) responsible for the hydrolysis of the chitin polymer (a 74 β -1,4-linked N-acetylglucosamine), a structural component found in the cell walls of fungi, 75 insects, a variety of crustaceans and nematode eggs (Kesari et al, 2015). Interestingly, 76 although the chitin is not present in plants, different subgroups of chitinase genes were 77 identified in plants (Kesari et al, 2015).…”

“…Chitinases (EC 3.2.1.14) are a family of 73 glycosyl hydrolases (GHs) responsible for the hydrolysis of the chitin polymer (a 74 β -1,4-linked N-acetylglucosamine), a structural component found in the cell walls of fungi, 75 insects, a variety of crustaceans and nematode eggs (Kesari et al, 2015). Interestingly, 76 although the chitin is not present in plants, different subgroups of chitinase genes were 77 identified in plants (Kesari et al, 2015). Plant chitinase proteins are generally divided into 78 six classes, I to VI (Patil et al, 2000).…”

“…Both families 80 exhibit diversity in their nucleic acid sequences, protein structures, substrate specificities, 81 sensitivity to inhibitors and mechanisms of catalysis. Along with active chitinases, the 82 plant genome also consists of a large number of sequences encoding catalytically inactive 83 chitinases that are referred to as chitinase-like (CTL) proteins (Kesari et al, 2015). A few 84 studies suggested that the likely substrates of plant CTL proteins may be arabinogalactan 85 protein, chitooligosaccharides, N-acetylchitooligosaccharides and other 86 GlcNAc-containing glycoproteins or glycolipids, but the substrates of most plant CTL 87 proteins remain uncertain (Sanchez-Rodriguez et al, 2012;Zhong et al, 2002;van Hengel 88 et al, 2001).…”

“…Different types of chitinases were induced by differential pathogen attack and have been 403 characterized as pathogenesis-related (PR) proteins (Kesari et al, 2015;van Loon et al, 404 2006). Phylogenic analysis showed that LcCHI2 is a homologue of several reported PR3 405 proteins, including TaPR3, HvPR3, CaCHI2, pcht28 and AtPR3 ( Figure S2) (Verburg and 406 Huynh, 1991;Hong and Hwang, 2002;Tabaeizadeh et al, 1999;Shin et al, 2008;Scheler 407 et al, 2016).…”

A novel function for globulin in sequestering plant hormone: Crystal structure of Wrightia tinctoria 11S globulin in complex with auxin

“…For example, lectin, Kunitz trypsin inhibitor, albumin, and chitinase are involved in a defensive role 10–15 , whereas the nutritional requirement of the seed is defined by globulins, which represent the most widely distributed group of seed-storage protein 16 . These storage proteins are synthesized during seed formation, accumulate in the endosperm layer and are used in later stages of seed development.…”