氧化胁迫诱导白腐真菌漆酶基因高效表达的分子机制及其生物学意义研究

Previous research have suggested that the laccase activity and the expression of laccase gene in white rot fungi can be induced by the oxidative stress caused by exogenous stress factors. The high expression of laccase is thought as a part of the adaptive response system of white rot fungi to the oxidative stress conditions. Laccase may be involved in the defence against the oxidative stress. However, how can the oxidative stress stimulate the expression of laccase gene? Is it ture that laccase really plays an important role in fungal oxidative stress defense? What is the the mechanism of laccase involved in the defence against the oxidative stress? All of above questions remain unsolved. In our previous research, we find that the transcription of laccase gene in white rot fungus Pleurotus ostreatus BP2 can be significantly stimulated by the oxidative stress caused by exogenous hydrogen peroxide. In this project, based on our previous research, we plan to study the biological significance and molecular mechanism of inducing the high expression of laccase gene in white rot fungus Pleurotus ostreatus BP2 by the oxidative stress. Our study aims to further reveal the biological function and mechanism of fungal laccase involved in the defence against the oxidative stress. Our work will provide new insights and informations for unveiling the responsive mechanisms of white rot fungi to the oxidative stress conditions. It will contribute to revealing the mechanism of how white rot fungi resist to the oxidative stress. Our research can also be helpful to shed light on the biological function of laccase in white rot fungi. In addition, this research will lay a solid theoretical foundation for highly improving the ability of degrading the biomass and xenobiotics such as environmental pollutants by white rot fungi.

已有研究表明氧化胁迫条件能够诱导增强白腐真菌漆酶活性和漆酶基因的表达，漆酶表达的增强可能作为一种对抗氧化胁迫的应答机制，白腐真菌漆酶可能参与抵抗氧化胁迫，但氧化胁迫是如何诱导漆酶基因高效表达的？漆酶是否的确在白腐真菌抵抗氧化胁迫的过程中发挥重要作用？作用的具体机制又是什么？这些问题尚未解决值得深入研究。我们前期研究发现外源过氧化氢诱发的氧化胁迫能够显著诱导增强白腐真菌Pleurotus ostreatus BP2的漆酶基因的转录。本项目将在我们前期工作基础上，深入研究氧化胁迫诱导白腐真菌漆酶基因高效表达的分子机制及其生物学意义，揭示漆酶参与白腐真菌抵抗氧化胁迫的生物学功能及其作用机制。研究意义在于为深入揭示白腐真菌对氧化胁迫的应答响应机制和抵抗作用机理提供有价值的新信息新观点，为阐明漆酶在白腐真菌体内的生物学功能提供新证据，为进一步提高白腐真菌降解生物质和异生物质的能力奠定更坚实的理论基础

白腐真菌是能在纯系培养中有效地将木质素彻底降解为CO2 和H2O 的一类微生物，漆酶是白腐真菌分泌产生的一种重要木质素降解酶，漆酶具有广泛的底物作用范围和独特的生物降解功能，在工业和环境生物技术领域都具有巨大的应用价值和潜力，因此对白腐真菌漆酶的研究具有重要的科学意义和实践价值。本项目围绕白腐真菌漆酶与抵抗氧化胁迫之间的关系，研究了氧化胁迫诱导白腐真菌漆酶基因高效表达的分子调控机制及其生物学意义。从Pleurotus ostreatus BP2等几株白腐真菌菌株中克隆获得了不同漆酶结构基因及其全长cDNA序列，利用基因组步移技术克隆获得了漆酶基因的上游启动子调控序列，初步鉴定了可能参与氧化胁迫转录调控的顺式作用调控元件。外源过氧化氢的处理对真菌细胞造成了氧化胁迫和损伤，外源过氧化氢诱发的氧化胁迫能够诱导增强白腐真菌漆酶的活性和漆酶基因的转录。进一步研究了外源过氧化氢介导的氧化胁迫诱导白腐真菌漆酶基因高效表达的调控分子机制，探求和鉴定能够参与氧化胁迫诱导漆酶基因转录的反式作用因子和顺式作用DNA调控元件，研究其相互作用，力图揭示胁迫条件调控漆酶基因转录的作用和机制。进一步研究了漆酶在白腐真菌抵抗氧化胁迫中的具体功能和作用，验证了漆酶及其表达在抵抗氧化胁迫中发挥作用，探究了在抵抗氧化压力过程中漆酶的表达与已知的其它抗氧化防御系统之间的作用关系。另外还较为系统地阐明了其它不同诱导物对白腐真菌漆酶基因以及一个漆酶基因家族中不同同工酶基因的转录调控作用和调控模式。本研究结果为深入揭示白腐真菌对氧化胁迫的应答响应机制和抵抗作用机理提供了有价值的新信息和新观点，同时有利于更加深入地解析白腐真菌漆酶高效合成规律和漆酶基因表达调控机理，为进一步提高白腐真菌降解生物质和环境污染物等异生物质的能力以及更好地开发利用白腐真菌这类宝贵的微生物资源奠定了更为坚实有效的理论基础。