黑曲霉htmA基因的分离鉴定及其功能分析

本研究通过分析比较黑曲霉基因组与人、哺乳动物和酿酒酵母基因组序列同源性,首次分离鉴定了黑曲霉htmA基因,该基因长3459bp,编码1083个氨基酸。已知真核生物的htmA基因编码一种类α-甘露糖苷酶I的非必须蛋白HTMA,在内质网中参与降解非正确折叠的糖蛋白,htmA基因的破坏会延迟非正确折叠糖蛋白的降解。为分析htmA基因在黑曲霉中的功能,运用同源重组技术敲除黑曲霉基因组中的htmA基因,获得htmA基因缺失突变菌株,并进行了缺失株外源漆酶分泌能力的检测。结果表明黑曲霉htmA基因的破坏延缓了外源漆酶的降解,由此推测黑曲霉htmA基因编码蛋白HTMA具有与酵母、哺乳动物HTM1P/EDEM类似的功能作用。

Identification and functional analysis of the htmA gene in Aspergillus niger

The htmA gene from Aspergillus niger was identified by a comparative genomics approach which shares high homology with Saccharomyces cerevisiae htmA. The gene was 3459 bp encoding a protein of 1083 amino acids. It was known that htmA gene encodes for a non-essential protein that is homologous to α-mannosidase I and that is required for ER degradation of misfolded glycoproteins in eukaryotes. The down- regulation of htmA results in the delay of ER associated degradation. The htmA disruption mutant was constructed by gene targeting technique and was analysed for its secretion activity of heterologous laccase. The results revealed that the disruption of htmA gene in A. niger delayed the degradation of heterologous protein. It suggested that htmA encoding protein HTMA in A. niger has the similar function with HTM1P/EDEM in yeast/ mammalian.