Abstract:
Xylanases are produced from different sources like fungi, bacteria, archaea, and insects however
bacteria and fungi are considered the major source. This investigation was designed to characterize
Aspergillus xylanases through in silico approach. To identify fungal xylanases with the best
catalytic ability and efficient degradation of xylan, characterization, structure prediction and
expression of xylanase from different Aspergillus strains i-e Aspergillus oryzae, Aspergillus
fumigatus, Aspergillus flavus and Aspergillus luchuensis were predicted under this study.
Functional domain GH10 was identified in Aspergillus xylanases and was found conserved in
different sequences of fungal xylanases through multiple sequence alignment. The phylogenetic
tree confirmed the close relationship between Aspergillus flavus and Aspergillus oryzae. Different
fungal xylanase production was in the extracellular compartment of the cell. Xylanase genes were
identified on chromosomes 1,2,3,4,5,6 and 8 followed by gene structure analysis which concluded
that xylanases genes mostly consist of exons along with introns. Conserved 5 motifs were
identified that encode for the GH10 functional domain of fungal xylanases. Different
physicochemical properties were analyzed which concluded that fungal xylanases were high
molecular weight proteins that were acidic. The signal peptide was identified in different fungal
xylanases that were between 27-32 aa residues and were cleaved to prepare the fungal xylanases
sequences for modeling. Through modeling 4 suitable structures were predicted for fungal
xylanases which had ERRAT values between 95-98%, disallowed regions were minimum as well,
along with QMEAN value that was between 0.8-0.83 and favorable regions were greater in
number. Through differential gene expression analysis, the expression of considered xylanases
genes in Aspergillus fumigatus was observed. This study provides knowledge about the structural,
chemical, and physical properties and expression of the fungal xylanases genes which can clarify
its basic molecular mechanism and make xylanase utilization in different processes common.
