Evolution, Homology Conservation, and Identification of Unique Sequence Signatures in GH19 Family Chitinases

Abstract

The discovery of GH (Glycoside Hydrolase) 19 chitinases in Streptomyces sp. raises the possibility of the presence of these proteins in other bacterial species, since they were initially thought to be confined to higher plants. The present study mainly concentrates on the phylogenetic distribution and homology conservation in GH19 family chitinases. Extensive database searches are performed to identify the presence of GH19 family chitinases in the three major super kingdoms of life. Multiple sequence alignment of all the identified GH19 chitinase family members resulted in the identification of globally conserved residues. We further identified conserved sequence motifs across the major sub groups within the family. Estimation of evolutionary distance between the various bacterial and plant chitinases are carried out to better understand the pattern of evolution. Our study also supports the horizontal gene transfer theory, which states that GH19 chitinase genes are transferred from higher plants to bacteria. Further, the present study sheds light on the phylogenetic distribution and identifies unique sequence signatures that define GH19 chitinase family of proteins. The identified motifs could be used as markers to delineate uncharacterized GH19 family chitinases. The estimation of evolutionary distance between chitinase identified in plants and bacteria shows that the flowering plants are more related to chitinase in actinobacteria than that of identified in purple bacteria. We propose a model to elucidate the natural history of GH19 family chitinases.

Identification and cloning of class II and III chitinases from alkaline floral nectar of Rhododendron irroratum, Ericaceae

“…However, GH 19 chitinase appears to be restricted to plants, fungi, and bacteria (Iseli et al 1996;Udaya Prakash et al 2010;Adrangi and Faramarzi 2013). Actinobacteria and purple bacteria might have acquired GH 19 chitinase genes from plants (Udaya Prakash et al 2010). The chitinases of the two different families do not share amino acid sequence similarity, and have completely different 3-dimensional (3D) structures and molecular mechanisms (Hamid et al 2013).…”

“…GH18 chitinases have a large distribution in organisms, including plants, bacteria, fungi, mammals, and viruses. However, GH 19 chitinase appears to be restricted to plants, fungi, and bacteria (Iseli et al 1996;Udaya Prakash et al 2010;Adrangi and Faramarzi 2013). Actinobacteria and purple bacteria might have acquired GH 19 chitinase genes from plants (Udaya Prakash et al 2010).…”

Chitinolytic functions in actinobacteria: ecology, enzymes, and evolution

“…According to the data obtained from biochemical and site-directed-mutagenesis studies of the active site of a GH46 chitosanase (Boucher et al 1995; Fukamizo 2000; Lacombe-Harvey et al 2009; Marcotte et al 1996; Robertus et al 1998; Wohlkönig et al 2010), it is conceivable that GH19 chitinases and GH46 chitosanases could arise from a less specialized common ancestor “half-chitinase, half-chitosanase.” Following this hypothesis, evolution of the chitinase function would occur in plants, resulting in formation of GH19 family which then was transferred to actinobacteria by HGT (Udaya Prakash et al 2010). Evolution of chitosanase function would occur in Gram-positive bacteria (perhaps in parallel in high- and low-G+C branches) resulting in formation of the GH46 family.…”

The functional effect of Gly209 and Ile213 substitutions on lysozyme activity of family 19 chitinase encoded by cyanophage Ma-LMM01

“…ND Not detected Fish Sci (2011) 77:665-670 669 research focusing on the role of the Tyr residue is necessary to determine its contribution in sugar binding. Family 19 chitinases are hypothesized to be horizontally transferred from higher plants to bacteria [29,30]. In the evolutionary history of the family 19 chitinases, mutation in key residues (ex.…”

“…Nineteen cluster III family 19 chitinases (17 genes in bacterial genomes and 2 genes in bacteriophages) were in the current database [8,29]. Two residues, Asn124 and Lys165 (according to the barley family 19 chitinase numbering), are presumed to be responsible for the subsite -3 activity.…”