A phosphoketolase Mpk1 of bacterial origin is adaptively required for full virulence in the insect-pathogenic fungus Metarhizium anisopliae
A phosphoketolase Mpk1 of bacterial origin is adaptively required for full virulence in the insect-pathogenic fungus Metarhizium anisopliae
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DOI：
10.1111/j.1462-2920.2009.01961.x
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发表时间：
2009-09-01
影响因子：
5.1
通讯作者：
Wang, Chengshu
中科院分区：
文献类型：
--
作者：
Duan, Zhibing;Shang, Yianfang;Wang, Chengshu
磷酸酮醇酶途径的戊糖代谢已经在细菌中得到了很好的表征。在本文中，我们报道了在昆虫病原真菌绿僵菌（Metarhizium anisopliae）中磷酸酮醇酶同源物Mpk1的鉴定。系统发育分析表明，真菌磷酸酮酶是细菌来源，并分为两个超科。频繁的基因丢失或缺乏获得在特定的真菌谱系或物种中是明显的。mpk1基因在富含海藻糖的昆虫血淋巴中高表达，但在昆虫角质层或富含碳水化合物的植物根分泌物中表达较差。此外，木糖、海藻糖、葡萄糖或蔗糖等不同糖均可上调mpk1基因表达和酶活性。同源重组产生的mpk1零突变体在以木糖为唯一碳源的培养基上生长与野生型相似。然而，昆虫（烟草角虫，Manduca sexta）的生物测定显示，Delta mpk1的毒力显著降低。本研究结果表明，水平转移的Mpk1对真菌在昆虫血腔内的繁殖具有重要的生态位适应作用。根据植物向植食昆虫和昆虫病原真菌传递碳水化合物的过程，讨论了真菌磷酸酮醇酶途径的需要量与三营养关系。
P>Pentose metabolism through the phosphoketolase pathway has been well characterized in bacteria. In this paper, we report the identification of a phosphoketolase homologue Mpk1 in the insect-pathogenic fungus Metarhizium anisopliae. Phylogenetic analysis showed that fungal phosphoketolases are of bacterial origin and diverged into two superfamilies. Frequent gene loss or lack of acquisition is evident in specific fungal lineages or species. The mpk1 gene is highly expressed when grown in trehalose-rich insect haemolymph but poorly induced by insect cuticle or carbohydrate-rich plant root exudate. In addition, mpk1 gene expression and enzyme activity could be upregulated by different sugars including xylose, trehalose, glucose or sucrose. mpk1 null mutants generated by homologous recombination grew similar to the wild type of M. anisopliae on medium amended with xylose as a sole carbon source. However, insect (tobacco hornworm, Manduca sexta) bioassays showed significantly reduced virulence in Delta mpk1. The results of this study suggest that the horizontally transferred Mpk1 in M. anisopliae plays an important niche adaptation role for fungal propagation in insect haemocoel. Following the carbohydrate flux from plants to plant-feeding insects and insect pathogenic fungi, a tritrophic relationship is discussed in association with the requirement of fungal phosphoketolase pathway.