EglC, a New Endoglucanase from Aspergillus niger with Major Activity towards Xyloglucan
2002; American Society for Microbiology; Volume: 68; Issue: 4 Linguagem: Inglês
10.1128/aem.68.4.1556-1560.2002
ISSN1098-5336
AutoresAlinda A. Hasper, Ester Dekkers, Marc H. W. van Mil, Peter J. I. van de Vondervoort, Leo H. de Graaff,
Tópico(s)Enzyme Production and Characterization
ResumoABSTRACT A novel gene, eglC , encoding an endoglucanase, was cloned from Aspergillus niger . Transcription of eglC is regulated by XlnR, a transcriptional activator that controls the degradation of polysaccharides in plant cell walls. EglC is an 858-amino-acid protein and contains a conserved C-terminal cellulose-binding domain. EglC can be classified in glycoside hydrolase family 74. No homology to any of the endoglucanases from Trichoderma reesei was found. In the plant cell wall xyloglucan is closely linked to cellulose fibrils. We hypothesize that the EglC cellulose-binding domain anchors the enzyme to the cellulose chains while it is cleaving the xyloglucan backbone. By this action it may contribute to the degradation of the plant cell wall structure together with other enzymes, including hemicellulases and cellulases. EglC is most active towards xyloglucan and therefore is functionally different from the other two endoglucanases from A. niger , EglA and EglB, which exhibit the greatest activity towards β-glucan. Although the mode of action of EglC is not known, this enzyme represents a new enzyme function involved in plant cell wall polysaccharide degradation by A. niger .
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